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Spatial synchrony and cycles are common features of forest insect pests, but are often studied as separate phenomenon. Using time series of timber damage caused by Dendroctonus frontalis Zimmermann (Coleoptera: Curculionidae) (southern pine beetle) in 10 states within the southern United States, this study examines synchrony in D. frontalis abundance, the synchronizing effects of temperature extremes, and the evidence for shared cycles among state populations. Cross-correlation and cluster analyses are used to quantify synchrony across a range of geographic distances and to identify groups of states with synchronous dynamics. Similar techniques are used to quantify spatial synchrony in temperature extremes and to examine their relationship to D. frontalis fluctuations. Cross-wavelet analysis is then used to examine pairs of time series for shared cycles. These analyses suggest there is substantial synchrony among states in D. frontalis fluctuations, and there are regional groups of states with similar dynamics. Synchrony in D. frontalis fluctuations also appears related to spatial synchrony in summer and winter temperature extremes. The cross-wavelet results suggest that D. frontalis dynamics may differ among regions and are not stationary. Significant oscillations were present in some states over certain time intervals, suggesting an endogenous feedback mechanism. Management of D. frontalis outbreaks could potentially benefit from a multistate regional approach because populations are synchronous on this level. Extreme summer temperatures are likely to become the most important synchronizing agent due to climate change.

Higher temperatures projected under current climate change models are generally predicted to exert an overall positive effect on the success of invasive insects through increased survivability, developmental rates and fecundity, and by facilitating geographic range expansion. However, these effects have primarily focused on the shifts in winter temperatures with limited attention to the role that summer heat may play in shaping species ranges or fitness. We examined the thermal ecology of an ecologically important invasive forest insect, the hemlock woolly adelgid (Adelges tsugae), by determining survival during its summer dormancy phase under increasing temperature regimens. From laboratory and field experiments, we documented a positive association between increased temperatures and duration of exposure, and A. tsugae mortality. Adelges tsugae mortality was minimal ( 30 °C). At the warmest, southernmost edge of their range, field mortality of A. tsugae ranged from 8.5 to 81.9% and was strongly correlated with site temperature regimens. Further, we found no significant differences in A. tsugae survival between populations collected from Maine and Georgia, and over a 3-year period within Georgia, indicating that A. tsugae may not be acclimating to heat. These results highlight the importance of including summer temperatures in studies regarding increased temperatures on insect dynamics, and may alter historical predictions of climate change impacts on invasive insects and the conservation of forest ecosystems.

Outbreaks of insect pests periodically cause large losses of volume in Canada’s forests. Compounded with climate change, outbreaks create significant challenges for managing the sustainable delivery of ecosystem services. Current methods to monitor damage by these pests involve both field and aerial surveys. While relatively cost effective and timely, aerial survey consistency and spatial coverage may be insufficient for detailed monitoring across Canada’s vast forest-land base. Remote sensing can augment these methods and extend monitoring capabilities in time and space by incorporating knowledge of pest-host interactions and of how damage translates into a remote sensing signal for detection and mapping. This review provides a brief introduction to major forest insect pests in Canada (two bark beetles (Coleoptera: Curculionidae) and six defoliators) and the damage they cause, a synthesis of the literature involving aerial survey and remote sensing, and a discussion of how these two approaches could be integrated into future pest monitoring from a Canadian perspective. We offer some lessons learned, outline roles that remote sensing could serve in a management context, and discuss what ongoing and upcoming technological advances may offer to future forest health monitoring.

Financial support was provided by the Department of Science and Technology (DST)/National Research Foundation (NRF) Centre of Excellence in Tree Health Biotechnology. This project was supported by multiple grants from the NRF, South Africa, including the grant specific unique reference number (UID) 83924.

Canada is host to a number of native and introduced forest insects that negatively affect the goods and services provided by forests. Some insects affect forests on a fairly predictable, ongoing basis, while others have impacts that are intermittent, difficult to predict, and sometimes catastrophic. Economic analysis has provided important insights that have informed our understanding of the impact of forest pests and pest management. At the same time, interactions between forests, forest insects, forest management, and economic welfare are complex, and credible assessments may be time consuming and may not always provide results with the certainty sought by policy-makers. This paper reviews the contribution of economics to forest pest management in Canada and suggests future directions for this important field of research.

Insects use semiochemicals to mediate important behaviours such as mating, oviposition, and foraging for resources. Chemical ecology research aims to identify these message-bearing chemicals and develop synthetic copies of semiochemicals for use in integrated pest management (IPM). There has been, and continues to be, an extensive research effort to understand the chemical ecology of various insects considered to be pests of forests in Canada. Canadian chemical ecology research has had an impact on IPM of forest insect pests in Canada and around the world. Canadian researchers have been involved in the identification of semiochemicals used by forest insects and the development and implementation of semiochemical-based management tactics for forest pest management. Semiochemicals have been incorporated into forest pest management for a variety of insect taxa primarily as tools to monitor and control forest insect pests in Canada. The goals of the current review are to: (1) highlight research conducted on semiochemical-based management of forest pests in Canada; (2) discuss the current and potential uses of semiochemicals in IPM of forest pests in Canada; and (3) evaluate potential areas for increased research and implementation of semiochemicals into the management of forest pests in Canada.

The ability of insect pathogens (in particular viruses) to cause long-term stable limit cycles in their hosts was first demonstrated theoretically by Anderson and May (1980, 1981). Since then, there has been extensive discussion and controversy about whether the cycles seen in temperate forest insects (Varley 1949; Baltensweiler 1964; Baltensweiler et al. 1977) are caused by pathogens (Myers 1988) and whether the addition of greater biological detail to the simple Anderson and May model increases or decreases the likelihood of cycles. The Anderson and May model is a set of coupled ordinary differential equations, related to the Lotka-Volterra predator-prey model, in which neither the host nor the pathogen shows any density-dependent self-regulation. Since the type of forest insect that shows long-term cycles frequently severely depletes its food supply, it is natural to ask whether the addition of host selfregulation makes cycles more likely. This was first done by Bowers et al. (1993), who concluded that density dependence was unlikely to increase the probability of population cycles, although the opposite conclusion was reached the following year by Dwyer (1994). The apparent contradiction was reconciled by White et al. (1996), who showed that the two studies had incorporated host self

Surveying multiple invasive pest species at the same time can help reduce the cost of detecting new pest invasions. In this paper, we describe a new method for mapping the relative likelihood of pest invasion via plant propagation material in a geographic setting. The method simulates the invasion of a range of pest species, including arrival in an uninvaded area, spread, and survival in a novel landscape, using information on the spatial and temporal distribution of the suitable host crop species and tentative knowledge of the spread and survival capacities of the target pests. The methodology is applied to a gridded map in which each map cell represents a site in a landscape. The method uses stochastic simulations to depict plausible realizations of the invasion outcomes and estimate the distribution of pest invasion likelihood for each cell in the area of concern. The method then prioritizes the cells based on the stochastic invasion outcomes using a pairwise stochastic dominance rule and a hypervolume indicator. We demonstrate the approach by assessing the relative likelihood of pest invasion for strawberry production in Finland. Our method helps to differentiate sites in a landscape using both the estimates of pest invasion risk and their uncertainty. It can be applied to prioritize sites for plant health surveys and allocate survey resources among large geographic regions. The approach is generalizable and can be used in situations where knowledge of the harmful pest species is poor or nonexistent.

Forest insects are major disturbances that induce tree mortality in eastern coniferous (or fir-spruce) forests in eastern North America. The spruce budworm (SBW) (Choristoneura fumiferana [Clemens]) is the most devastating insect causing tree mortality. However, the relative importance of insect-caused mortality versus tree mortality caused by other agents and how this relationship will change with climate change is not known. Based on permanent sample plots across eastern Canada, we combined a logistic model with a negative model to estimate tree mortality. The results showed that tree mortality increased mainly due to forest insects. The mean difference in annual tree mortality between plots disturbed by insects and those without insect disturbance was 0.0680 per year (P0.0001, T-test), and the carbon sink loss was about 2.87t C ha(-1) year(-1) larger than in natural forests. We also found that annual tree mortality increased significantly with the annual climate moisture index (CMI) and decreased significantly with annual minimum temperature (T min), annual mean temperature (T mean) and the number of degree days below 0°C (DD0), which was inconsistent with previous studies (Adams et al. 2009; van Mantgem et al. 2009; Allen et al. 2010). Furthermore, the results for the trends in the magnitude of forest insect outbreaks were consistent with those of climate factors for annual tree mortality. Our results demonstrate that forest insects are the dominant cause of the tree mortality in eastern Canada but that tree mortality induced by insect outbreaks will decrease in eastern Canada under warming climate.

Detection of newly established populations of Agrilus planipennis Fairmaire, the most destructive forest insect to invade the United States, remains challenging. Regulatory agencies currently rely on artificial traps, consisting of baited three-sided panels suspended in the canopy of ash (Fraxinus spp.) trees. Detection trees represent another survey option. Ash trees are girdled in spring to attract ovipositing A. planipennis females then debarked in fall to assess larval presence and density. From 2008-2010, systematic grids of detection trees and artificial traps were established across a 390-km(2) area for the SLow Ash Mortality pilot project. We compared probabilities of detection associated with detection trees and artificial traps along varying A. planipennis density proxies estimated as distance-weighted averages of larval counts (detection trees) or adult captures (traps) within 800 m of each detection tree or trap. Detection trees were consistently more likely to be positive, that is, detect A. planipennis, than traps in all three years, even when traps were placed in canopies of detection trees. Probability of detection with a single detection tree was >50% when density proxies for the area were

An analysis of forest tent caterpillar Malacosoma disstria defoliation records from Ontario and Quebec over the period 1938–2002 indicates that outbreaks recur periodically and somewhat synchronously among regions of the two provinces. Cluster analysis revealed that the most strongly periodic, large-scale, synchronized fluctuations occurred within three regions: northwestern Ontario, eastern Ontario/western Quebec and southeastern Quebec. Defoliation in the vast surrounding hinterlands tended to be infrequent and sporadic, loosely tracking defoliation in the core outbreak regions. One small cluster in northeastern Ontario stood out as anomalous, as a result of an increasing trend in the duration of periodic defoliation episodes, marked by an unprecedented double-wave of defoliation that persisted from 1992 to 1999. This is the precise area where, in the early 2000s, trembling aspen Populus tremuloides stems were mapped as being in a state of decline of unprecedented severity and extent. Our results suggest forest tent caterpillar has the potential to cause significant impacts on forest health and, hence, carbon budgets in east-central Canada and that the forest tent caterpillar deserves more attention as a model system of forest insect disturbance ecology.

Long-distance introductions of new invasive species have often been driven by socioeconomic factors, such that traditional “biological” invasion models may not be capable of estimating spread fully and reliably. In this study we present a new methodology to characterize and predict pathways of human-assisted entries of alien forest insects. We have developed a stochastic quantitative model of how these species may be moved with commodity flow through a network of international marine ports and major transportation corridors in Canada. The study makes use of a Canadian roadside survey database and data on Canadian marine imports, complemented with geo-referenced information on ports of entry, populated places and empirical observations of historical spread rates for invasive pests. The model is formulated as a probabilistic pathway matrix, and allows for quantitative characterization of likelihoods and vectors of new pest introductions from already or likely-to-be infested locations. We applied the pathway model to estimate the rates of human-assisted entry of alien forest insect species across Canada as well as cross-border transport to locations in the US. Results suggest a relatively low nationwide entry rate for Canada when compared to the US (0.338 new forest insect species per year vs. 1.89). Among Canadian urban areas, Greater Toronto and Greater Vancouver appear to have the highest alien forest insect entry potential, exhibiting species entry rates that are comparable with estimated rates at mid-size US urban metropolises.

International trade is widely acknowledged as a conduit for movement of invasive species, but few studies have directly quantified the invasion risk confronting individual locations of interest. This study presents estimates of the likelihood of successful entry for alien forest insect species at more than 3,000 urban areas in the contiguous United States (US). To develop these location-specific estimates, we first utilized historical merchandise imports and insect incursions data to estimate an annual US rate of alien insect species establishment. Next, we used historical pest interception data to calculate the proportion of all insects arriving at US ports of entry that are associated with forest hosts. We then combined these results to estimate a nationwide establishment rate specifically for alien forest insects. Finally, we employed international and domestic commodity flow networks to allocate this nationwide rate to individual US urban areas. For 2010, we estimated the nationwide rate as 1.89 new alien forest insect species per year. While the establishment rates observed at most urban areas were low (

Landscape composition and physiognomy affect community structure and species distribution across space and time. The pine processionary moth (PPM) (Thaumetopoea pityocampa Den. & Schiff., Lepidoptera, Notodontidae) is a common pine defoliator throughout southern Europe and Mediterranean countries. We surveyed the spatiotemporal distribution of the PPM in a pine plantation forest in southwestern France and used the density of the winter nests as a proxy for population density. The study spanned 4 years (2005–2008) and showed a high temporal variability in nest density. We found a strong edge effect with nest densities at stand edges more than twice as large as within-stand densities. At the landscape scale, the spatial distribution of the moth exhibited a significant spatial autocorrelation in 3 out of 4 years of our study. The spatial scales of the autocorrelation ranged from ca. 2 km to more than 22 km. We found a positive correlation between spatial distributions corresponding to certain sampling years, but the relationship was not systematic. Landscape configuration appeared to be an important driver of the PPM spatial pattern. Bivariate Moran’s I correlograms showed that patch richness density as well as the percentage of local landscape covered by various land uses were correlated with population density. The study showed that accounting for landscape characteristics may be important in order to understand forest insect pest distribution, even in cases where the host species is abundant and homogeneously distributed throughout the study area, e.g., pure plantation forests.

The sal heartwood borer or sal borer, Hoplocerambyx spinicornis Newman is the most devastating insect pest of Shorea robusta. It is not only due to the incidence and intensity of the pest but also due to the ecological and economic losses it causes due to periodically repeated outbreaks or epidemics of this pest in sal dominating areas. Complex life cycle and related problems further makes its management tough. The chapter discusses various aspects of this pest along with possible management options including researches being undertaken on sal heartwood borer.

International audience; Saproxylic beetles – associated with dead wood or with other insects, fungi and microorganisms that decompose it – play a major role in forest nutrient cycling. They are important ecosystem service providers and are used as key bio-indicators of old-growth forests. In France alone, where the present study took place, there are about 2500 species distributed within 71 families. This high diversity represents a major challenge for specimen sorting and identification. The PASSIFOR project aims at developing a DNA metabarcoding approach to facilitate and enhance the monitoring of saproxylic beetles as indicators in ecological studies. As a first step toward that goal we assembled a library of DNA barcodes using the standard genetic marker for animals, i.e. a portion of the COI mitochondrial gene. In the present contribution, we release a library including 656 records representing 410 species in 40 different families. Species were identified by expert taxonomists, and each record is linked to a voucher specimen to enable future morphological examination. We also highlight and briefly discuss cases of low interspecific divergences, as well as cases of high intraspecific divergences that might represent cases of overlooked or cryptic diversity.

Foliage-feeding forest insects have served as model systems in the study of animal populations for more than 50 years. Early studies emphasized identification of key mortality agents or density-dependent sources of mortality. However, these efforts became burdened by rhetorical ambiguity, and population ecologists are increasingly focusing on characterizing population behavior and identifying the processes that generate that behavior. Two types of behavior seem to be common in forest insect populations: periodic oscillations (population cycles) and spatial synchrony (synchronous fluctuations over large geographic areas). Several population processes (e.g., host-pathogen interactions) have been demonstrated to be capable of producing periodic oscillations, but the precise identity of these processes remains uncertain for most forest insects and presents a challenge to future research. As part of these efforts, a greater emphasis is needed on the use of statistical methods for detecting periodic behavior and for identifying other types of population behavior (e.g., equilibrium dynamics, limit cycles, transient dynamics). Spatial synchrony appears to be even more ubiquitous in forest insect populations. Dispersal and regional stochasticity (Moran effect) have been shown to be capable of producing synchrony, but again more research is needed to determine the relative contribution of these processes to synchrony observed in natural populations. In addition, there is a need to search for other types of time-space patterns (e.g., traveling waves, spiral waves) in forest insect populations and to determine their causes.

The Douglas-fir tussock moth, Orgyia pseudotsugata (McDunnough) (Lepidoptera: Lymantriidae) (Fig. 1), is a defoliator of significant importance in Douglas-fir and true-fir forests of western North America. Outbreaks of this insect have occurred in many regions, from British Columbia to Arizona and New Mexico, and from the Rocky Mountains to the Cascade and Siskiyou ranges of Washington, Oregon, and California. Since the first reported infestation at Chase, British Columbia, in 1916, several major outbreaks have occurred in stands where conditions changed rapidly in favor of tussock moth survival. Prominent among these outbreaks: in Idaho, 447,000 acres from 1944 to 1947,225,000 acres from 1961 to 1965, and 110,000 acres from 1971 to 1974; in Oregon, 438,000 acres from 1971 to 1974; and in Washington, 251,000 acres from 1971 to 1974.

Adelges tsugae (Hemlock Woolly Adelgid; HWA) is a non-native forest insect that causes defoliation and mortality of hemlock in the eastern US. We quantified the extent to which people are potentially affected by the spread of HWA infestation where they live and where they recreate. We also considered how these impacts might change through time using data from 2007, 2009, and 2011. The study area included hemlock stands in a 7500-km2 region of central Connecticut and central Massachusetts. We used sample-plot data on live basal area and vigor of hemlock stands to interpolate hemlock health characteristics for all hemlock stands in the study area. We estimated a loss of property values in the region of approximately $24.6 million USD. This estimate was conservative because there were insufficient data to fully quantify the economic losses associated with the death of hemlock trees and the degradation of recreational opportunities. The spatial extent of the HWA infestation suggests that both of the ...

Events in American forestry at the end of the last century resulted in the establishment of the first forest reserves in the United States. In 1898, a field party in the Black Hills Reserve discovered extensive areas of ponderosa pine trees killed by an unknown bark beetle. This anecdotal account describes the subsequent visit to the Hills in 1901 by Andrew D. Hopkins, a self-trained entomologist from West Virginia, to investigate the cause of these bark beetle “depredations.” Afterward, he described and named the beetle ( Dendroctonus ponderosae ), which is still important in forestry. The outbreak led to the creation in 1902 of the Division of Forest Insect Investigations, USDA, headed by Hopkins, who assigned Jesse Webb, the first American-trained forest entomologist, to study the beetle, thereby ushering in the discipline of forest entomology in this country.

Producción Científica, Aim of study: This paper reviews the global research during the last 6 years (2007-2012) on the state, trends and potential of remote sensing for detecting, mapping and monitoring forest defoliation caused by insects. Area of study: The review covers research carried out within different countries in Europe and America. Main results: A nation or region wide monitoring system should be scaled in two levels, one using time-series with moderate to coarse resolutions, and the other with fine or high resolution. Thus, MODIS data is increasingly used for early warning detection, whereas Landsat data is predominant in defoliation damage research. Furthermore, ALS data currently stands as the more promising option for operative detection of defoliation. Vegetation indices based on infrared-medium/near-infrared ratios and on moisture content indicators are of great potential for mapping insect pest defoliation, although NDVI is the most widely used and tested. Research highlights: Among most promising methods for insect defoliation monitoring are Spectral Mixture Analysis, best suited for detection due to its sub-pixel recognition enhancing multispectral data, and use of logistic models as function of vegetation index change between two dates, recommended for predicting defoliation.

In many forest insects, subpopulations fluctuate concurrently across large geographical areas, a phenomenon known as population synchrony. Because of the large spatial scales involved, empirical tests to identify the causes of synchrony are often impractical. Simple models are, therefore, a useful aid to understanding, but data often seem to contradict model predictions. For instance, chaotic population dynamics and limited dispersal are not uncommon among synchronous forest defoliators, yet both make it difficult to achieve synchrony in simple models. To test whether this discrepancy can be explained by more realistic models, we introduced dispersal and spatially correlated stochasticity into a mechanistic population model for the North American gypsy moth Lymantria dispar. The resulting model shows both chaotic dynamics and spatial synchrony, suggesting that chaos and synchrony can be reconciled by the incorporation of realistic dynamics and spatial structure. By relating alterations in model structure to changes in synchrony levels, we show that the synchrony is due to a combination of spatial covariance in environmental stochasticity and the origins of chaos in our multispecies model.

Forest-insect systems frequently show cyclic dynamics which has been of considerable interest to both experimental and theoretical ecologists. One important issue has been the manner in which density-dependence acting on the host population through resource competition influences the likelihood of population cycles. Existing models make contradictory predictions. Here, we explore two models that allow different forms of density-dependence to be examined. We find that host density-dependence can influence the persistence of the host-pathogen interaction, the likelihood of population cycles and the stability of the host-pathogen interaction. In particular, over-compensatory density-dependence is likely to lead to host-pathogen cycles while under-compensatory density-dependence can promote stability. We discuss these differences with reference to the different forms of intraspecific competition and recent developments in insect population ecology.

A host-pathogen model with free-living infective stages and host self-regulation has been investigated with a view to clarifying the possible role of pathogens in the cyclic dynamics of forest insect pests generally, and of a granulosis virus in the dynamics of the larch budmoth in particular. Contrary to previous related analyses, lacking self-regulation, no support is provided for the view that host-pathogen interactions alone are capable of generating cyclic dynamics of the type observed in forest Lepidoptera. Overall, cycles 'ire less likely here than in the absence of simple self-regulation, and parameters from field estimates usually fail to generate cycles

Strategies for the use of entomopathogenic viruses in the management of forest insect pests include the use of viruses by themselves or with other biocontrol or chemical agents applied simultaneously or separately at strategic time intervals. It is concluded that baculoviruses (nuclear polyhedrosis and granulosis viruses) have considerable potential as components of integrated forest insect pest management systems. The prime limiting factors in their large scale use at present are the high cost of virus production and underdevelopment of application technology. Their greatest potential will probably be realized when used as an indirect, or preventative, strategy with a view to preventing the occurrence of pest emergency situations.

A decision-tree approach to decision-making is described as one way to select the best available control-treatment alternative to suppress a forest insect pest. A systems model consisting of a set of differential equations is described as a way to organize available information and notions about the pest-host system into a format that will aid the decision-maker. A decision to control a gypsy moth infestation is presented as an example of one potential use for decision trees and compatible systems models.

The study of populations and population trends of a forest insect embraces a wide field of activity. By implication, it includes a consideration of all mortality and survival factors. Therefore, in developing this portion of the symposium, it will be necessary to refer briefly to other related topics to be covered later. In addition, to obtain a proper understanding of the subject under discussion, the mode of operation of some population influences that will not be introduced by other members of the symposium will have to be described.

Severe defoliation of aspen stands by the forest tent caterpillar, Malacosoma disstria Hbn., became apparent in 1948 in three widely separated regions in Ontario, and by 1949 it was clear that another general outbreak of this defoliator had begun. In 1950 the Forest Insect Survey (cf. McGugan, 1958) initiated an intensive program of observation, collecting, and rearing to record the progress of the outbreak and study the parasite complex of the insect. This paper compares the outbreak in the early ‘fifties’ with earlier ones, and attempts to describe the pattern of build-up and decline of forest tent caterpillar populations within extensive forested areas.

Three questions are asked in this paper.(1) Is the numerical stability of an insect species through time a function of the number of species of food eaten by that species?(2) Is the information content of a genus related to the stability of species in the genus?(3) Is the information content of an insect genus related to the number of species of food eaten by the species in that genus?Data in the Canadian Forest Insect Survey bulletins on Forest Macrolepidoptera are used to answer all three questions; data on parasitic Hymenoptera stored in museums are used to answer the third question. There is some indication that stability decreases with number of host species, and that information content of a genus is less, the less the stability of the species it contains. The evidence from both bodies of data suggests that information content of a genus is less, the greater the average number of species of food eaten by the species in the genus.

The forest entomologist is often called upon to inspect insect defolialion late in the season at a time when the feeding stage of the defoliator is no longer present in the trees.

The majority of specimens on which the following descriptions are based were collected as larvae and reared to maturity in British Columbia in the Forest Insect Survey, Forest Insect Investigations. Though this procedure has certain definite advantages, it presents some difficulties in description, the adults often being darker in colour and smaller in size than those captured in flight. It was also observed that the structures of the genitalia are sometimes more delicate in reared specimens, so that single adults were, at times, difficult to associate with the descriptions and with genitalia mounts in the Canadian National Collection. Five new species, a new subspecies, and the previously unknown female of a sixth species are described in this paper. Brief notes on the biology, the distribution, and host plants of some previously recorded species have also been included.

Among the more important predacious coccinellids in eastern North America is Hyperaspis binotata auct., which has been considered a general feeder on Toumeyella numismaticum (P. & M.), Pulvinaria spp., and other scale insects. A review of the specimens identified as H. binotata in the collections of the Forest Insect Laboratory, Sault Ste. Marie, has revealed, not only H. binotata (Say), but two apparently new species, descriptions of which are given in this paper. In addition to the material at Sault Ste. Marie, specimens were obtained from the Canadian National Collection and the Forest Biology Laboratory, Winnipeg, Manitoba.

The problems that arise in the development of sampling techniques are treated in sequence, the solutions illustrated being based on population studies on the spruce budworm in northwestern New Brunswick. Insect populations may be expressed in different ways, depending upon the objects of the sampling, and it is essential that these objects be carefully defined. In the spruce budworm studies the preparation of life tables is the primary objective, and population is expressed in terms of a basic unit (branch surface) and an absolute unit (the acre). The correct timing of sampling requires a knowledge of the insect's life history, and of the stability of the population in place and time. When insect signs (pupal cases, empty egg masses) are sampled, the retention factor gives rise to certain non-sampling errors. The mechanics of collecting foliage from tall trees is solved with the aid of aluminum pole pruners, extension ladders, tree trestles, and platforms. The mechanics of counting the insects by ocular examination of the foliage samples also gives rise to non-sampling errors, which can be minimized by adequate supervision and by check examination.The universe for which each life table is prepared is a homogeneous forest stand. It is shown that a collection unit smaller than a whole branch, or its longitudinal one-half, is unlikely to be suitable for the measurement of absolute population. Intertree variance is the major source of population variance for the budworm, and for most other insects that have been studied intensively. Significant variance is also associated with crown levels, and the pattern of vertical distribution of the budworm is not predictable. The criterion of representativeness can be satisfied, however, by drawing samples from four crown levels in such a way that the intensity of sampling is equal in each level. The design found suitable for the budworm consists of proportionate sampling within the crown, stratified sampling by crown stories within the stand (with sub-strata, when necessary, according to host species or flowering condition), and cluster sampling within strata. Samples may be drawn from the same trees during successive budworm generations, and show correlations which appear to arise from the preferences of ovipositing adults. The effect of the correlations on sampling design and analysis is discussed.The relation between mean and variance indicates that population data are represented satisfactorily by the negative binomial distribution; variance may be stabilized and additivity provided through the use of logarithmic transformation. Methods of calculating optimum sample size are illustrated for both the original and the transformed data. The cost function for the sampling design used in the budworm work is presented, and its use in the comparison of designs and the detection of limiting factors is demonstrated. The estimation of population per acre is achieved by means of regressions showing the relationships between foliage quantity, crown volume, and diameter of the trunk. Useful incidental data, including a measure of population intensity, and biological data for life tables, may be obtained during sampling. Also, the design can readily be modified to suit purposes of extensive insect survey or the biological assay of a single stimulus.It is concluded that neither sampling nor non-sampling errors are likely to be prohibitive in forest insect population work. The relative magnitude of sampling errors varies inversely with the population mean, however, and the preparation of complete life tables may not be practical at endemic population levels. In any one generation of the insect it is generally necessary to accept error limits that seem large in relation to those of laboratory experimentation. But using the same sampling plots over a period of years, replication is achieved in time as well as in place, so the formation of erroneous conclusions on epidemiological phenomena seems improbable.

Among others, Schwerdtfeger, 1931, Gosswald, 1934, and Morris, 1949, have used frass-drop samples as indirect measurements of the density of forest insect populations with some success. The method has also been used to assess the effects of various insecticides on the feeding of treated larvae (Rhumbler, 1929; Schwerdtfeger, 1930) and to study the influence of weather upon the feeding and development of forest insects (Monro, 1935).

L'auteur etudie le role de certains predateurs (Oiseaux et Mammiferes) vis-a-vis des Insectes forestiers. Etant homeothermes, les predateurs de ce type ont besoin de quantites prodigieuses de nourriture; par contre, celle-ci varie beaucoup et les ravages produits sur chaque espece de proie sont en consequence diminues. Le degre d'abondance des proies influe de facon variable sur la predation des differentes especes: si la densite des proies est basse, peu sont attaquees mais a mesure que la densite augmente, le nombre de proies attaquees augmente jusqu'a un certain niveau pour ensuite demeurer constant ou diminuer. En general, l'action des Mammiferes et des Oiseaux s'avere beaucoup plus complexe que celle des predateurs invertebres ou des parasites. Entre autres facteurs particuliers, nous devons faire entrer en ligne de compte l'amassage, et le gaspillage par alimentation excessive. La population des predateurs peut aussi varier selon le degre de densite des proies. Par exemple: a) Les accouplements des predateurs augmentent lorsque la population des proies augmente: les predateurs etant mieux nourris, ils s'accouplent plus. b) Le comportement des predateurs devient different dans un secteur particulier ou la densite des proies est plus forte. Ces deux facteurs importent beaucoup pour determiner les effets des predations mais malgre ceci, le mecanisme du peuplement des proies n'est pas toujours considerablement affecte. Lorsque les predateurs jouent un role mineur, ils agissent comme regulateurs secondaires, c'est-a-dire qu'ils reduisent l'amplitude des fluctuations de la population des proies.

These observations, dealing with noctuid larvae, were made while the writer was associated with the Canadian Forest Insect and Disease Survey. Twenty-four species have been examined: 9 in the Hadeninae, 10 in the Cucullinae, 3 in the Amphipyrinae, and 2 in the Catocalinae. The arrangement of the subfamilies follows that of McDunnough (1938). This material is being published because many of these species have not been included in Crumb (1956) and new data are presented on the species considered by him. The descriptions were made from living and preserved larvae. Notes on biologies, unless otherwise indicated, refer to those made by the writer in Manitoba and Alberta during the years 1944-1954. The hosts are those on which larvae have been reared to adults by the Forest Insect and Disease Survey, except in a few cases where the host is cited from the literature. “Free-living larvae”, are those that feed openly. When the number of instars is not known the larvae are described as antepenultimate, penultimate, and ultimate. In measurements, H.W. refers to head width, B.L., to total larval length, and B.W., to greatest larval width.

Study of lonchaeid material reared from cones of various coniferous trees in North America revealed five previously undescribed species of the genus Earomyia Zett. The composite nature of cone-infesting lonchaeidae has not been understood and at least four of the species treated here have been considered as a single species (Keen, 1938, 1952). Much of the material studied, particularly that reared by various Forest Insect Investigations officers of the United States Bureau of Entomology and Plant Quarantine (bearing Hopkins U.S. numbers), has been misidentified as Earomyia viridana (Mg.) (Keen, op. cit.), Lonchaea albitarsis Zett., L. rufitarsis Macq., L. polita Say, and others.

Six species of Proctolaelaps, found associated with insect pests of pine forests in the southeastern United States, are described and illustrated. These are: P. bickleyi (Bram), P. fiseri Samšinák, P. hystrix (Vitzthum), and three new species, P. dendroctoni, P. dioryctriae, and P. hystricoides. Newly recorded for North America are P. fiseri, P. hystrix, and P. ulmi Hirschmann; distributions for the last two species include British Columbia. Garmania striata Westerboer is synonymized under P. bickleyi; the problem of the lewisi species complex, which includes P. bickleyi, P. lewisi (Garman and McGregor), and P. utahensis (Chant), is noted.Although the food habits of these and related mites are mostly unstudied, tentative observations indicate that some species are commensals and others are predators of their insect associates. Investigation of such mites and their relationships with forest pests is urged.

Three new species of ascid mites are described and illustrated: Proctolaelaps subcorticalis, Lasioseius corticeus, and Gamasellodes rectiventris. All are subcortical associates of bark beetles in North America.

The larch sawfly, Pristiphora erichsonii (Htg.), has been under observation in Manitoba and Saskatchewan since early in the present century. Recorded observations were somewhat fragmentary until 1937; since then systematic and detailed annual reports have been provided by the Forest Insect Survey and since 1948 intensive ecological and life table studies have been conducted by staff of the Winnipeg Laboratory at the Whiteshell Forest Reserve, Manitoba.

This list is a record of insects which have been found in or on Douglas fir in the northern Rocky Mountain region by personnel of the Forest Insect Field Laboratory at Coeur d'Alene, Idaho. It comprises insects which feed upon the tree, as well as the parasites and associates of these insects. Of the 153 species listed, 102 were collected by the writer while making a study of the Douglas fir beetle (Dendroctonus pseudotsugae Hopk.). The remainder are listed in the laboratory records and were collected by J. C. Evenden, R. E. Balch, H. J. Rust, and D. DeLeon.

The geometrid larvae feeding on spruce form a large and varied group. In collections taken from all parts of Canada where spruce is found, the Forest Insect Survey has identified 31 species (Brown, 1). To the best of the author's knowledge, there are descriptions for only 16 of these species. In this and the two following papers, seven more are described and two are redescribed.

Microorganisms form an important part of the natural forest ecosystem by participating in the recycling of the chemicals and energy of life. Fallen leaves, twigs, branches and trunks do not accumulate but are almost imme­ diately utilized by fungi, bacteria, protozoa, and nematodes and converted into chemicals that may be recycled into the production of new trees. Dead animals, including insects, are recycled in the same manner. Among all these groups of microorganisms certain species are known to be pathogenic, that is, they are able to cause disease in living plants and ani­ mals. For example, many diseases of trees are known to be caused by fungi, and bacterial diseases are common among animals.

The importance of small mammals as natural control factors for forest insect pests has been indicated by several investigators, particularly by Hewitt (8) and Graham (5) with respect to the larch sawfly, Pristiphora erichsoni Htg. and by Sim (9) with respect to the Japanese beetle, Popillia japonica Newm.