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Larvae of sugarcane soldier fly, Inopus rubriceps, pupated during autumn in sugarcane fields. Under conditions of moist soil and good cane growth, pupation occurred about 1 month later in northern and central Queensland than in southern Queensland and northern New South Wales, and this was related to soil temperature. the midpoint of the pupation period coincided with mean soil temperatures of 20-25° in each area. A laboratory experiment showed that pupation was inhibited at 25° and favoured by lower temperatures. the timing of pupation varied between years in one canefield in southern Queensland. Late pupation in 1991 was associated with small average size of larvae in early autumn and with dry soil conditions and poor cane growth. A high proportion of larvae failed to pupate before winter in this field in 1991. In normal years this carryover of larvae into winter was only about 10%. Male pupae were smaller than female pupae. Pupal weights were similar in each of the areas and years studied, but in some fields pupal weights declined with time during the pupation period.

Large differences in ratooning were observed between sugarcane clones in a variety trial that became infested with larvae of the sugarcane soldier fly Inopus rubriceps. To investigate this apparent resistance, pot experiments were carried out using two clones that responded differently in the trial. Soldier fly larvae reduced the number of ratoon shoots produced by both clones after harvest, with the commercial cultivar CP44–101 less affected than the experimental clone 81S595 under a range of growing conditions. This differential effect was consistent with field observations. The effect of soldier fly on plant growth prior to harvest was similar in both clones. Larval survival was independent of clone or larval density. The difference between the two clones appears due to a tolerance of soldier fly feeding by CP44–101. Pot experiments should be useful for screening commercial cultivars.

Larval populations of Inopus rubriceps (Macquart) in two sugarcane fields in southern Queensland, Australia, consisted of a mixture of small 7.5 mg) larvae during 20 mo of observation. Small larvae predominated during winter and spring. Large larvae were found closest to the soil surface in autumn (during the pupation period). The median depths of occurrence of large larvae during other months and of small larvae throughout the year were positively correlated with soil temperature and independent of soil moisture. Most larvae were within 15 cm of the surface in all months. Larvae were concentrated along the sugarcane rows.

A survey of damage caused by Inopus rubriceps to sugarcane was carried out in the Millaquin-Qunaba mill area near Bundaberg. Damage was less frequent in first and second ratoon crops than in older ratoons. An effect of sugarcane varieties was evident, but damage levels were the same for the 3 main varieties in the district. No damage was recorded in fields treated with suSCon Blue (controlled-release chlorpyrifos granules) against canegrubs (Coleoptera: Scarabaeidae). Damage was more frequent in cane fields that had been replanted immediately after ploughout of the previous crop than in those that had an interval without cane. This interval could be a bare fallow or a rotation with a vegetable crop. Other factors including rotary hoeing, past use of dieldrin, and use of chlorpyrifos EC at planting were not shown to affect the frequency of damage.

The soldier flies Inopus rubriceps (Macquart) and I. flavus (James) have periodically caused serious damage to sugar cane in southern and central Queensland. An analysis of data over 23 years reveals that outbreaks of the pestsare, in part, weather related. In both areas, outbreaks followed years with lower January—February minimum temperatures and lower February rainfall. In southern Queensland outbreaks also followed years with lower May minimum temperatures, higher June rainfall and higher July—August minimum temperatures. In central Queensland there was also a relationship with October rainfall. These factors are used with regression analysis and progressive elimination of insignificant variables to develop a method for forecasting outbreak levels.

Larvae of sugarcane soldier fly, Inopus rubriceps, began aggregating near sugarcane plants in troughs within 1 week of planting. By 6 weeks, almost 80% of larvae were found within 13 cm of the plants and only 5% were found 25-50 cm distant.

When field-collected larvae of Conoderus exsul and Agrypnus variabilis were maintained in the laboratory on insect (Inopus rubriceps) larvae, plant (germinating wheat seeds), or mixed (both larvae and seeds) diets, mortality was higher and growth rate lower (in A. variabilis) on the insect diet than the other diets. Head capsule measurements indicated at least five larval instars in C. exsul.

Pasture wireworm, Conoderus exsul (Sharp) fed more on larvae of the Australian soldier fly (Inopus rubriceps (Macquart)) than on germinating wheat seed when given a choice in the laboratory. Conversely, Agrypnus variabilis (Candeze), another wireworm found in New Zealand pastures, fed more on wheat seed. As determined by a serological technique (immuno-osmophoresis), 19% of C. exsul larvae, 20% of A. variabilis larvae and 80% of the adults of a staphylinid, Thyreocephalus oxthodoxus, (Olliff) collected in a pasture, had fed on I. rubriceps larvae. A predation rate of 12 soldier fly larvae/m2/day was estimated for C. exsul larvae. RESUME Determination serologique des Elateridae et des Staphylinidae predateurs d'Inopus rubriceps (Stratiomyidae), et alimentation de ces Elateridae sur vegetaux et animaux Pour determiner la valeur de Conoderus exsul Sharp comme predateur d'Inopus rubriceps Macquart, ravageur des prairies en Nouvelle Zelande, cet elateride a ete sur nourri des vegetaux et animaux. En 72 heures, il s'est alimente plus abondamment sur I. rubriceps que sur grains de ble. Par contre, un autre elateride des prairies, Agrypnus variabilis Candeze, a consomme plus de grains de ble que de I. rubriceps. Une technique serologique, l'immuno-osmophorese, a montre que 19% des larves de C. exsul, 20% de celles de A. variabilis et 80% des adultes du staphylin, Thyreocephalus orthodoxus Olliff recoltes dans la nature, avaient consomme des larves de I. rubriceps. En se basant sur la densite en Elaterides, sur le pourcentage de reactions positives, sur les taux de consommation quotidiens, et la periode d'observation de proies dans le tube digestif des predateurs, on peut estimer que 12 larves/m2/jour de I. rubriceps ont ete detruites par les larves de C. exsul pendant les 7 semaines de la periode utilisee.

A method for extracting the sugarcane soldier fly (Inopus rubriceps (Macquart)) larvae, pupae and remains from canefield soils by suspension in moving water is presented. Vertical and lateral distribution of larvae and pupae in relation to sugarcane plants was studied.

Selenate was applied at 11 rates increasing logarithmically from 1 to 105 g Se/ha to the surface of soil in pots containing ryegrass plants and soldier fly larvae. After 11 weeks the ryegrass plants had absorbed selenate to a maximum concentration of 2500 μg/g, and growth was diminished at 104 g Se/ha. Mortality of soldier fly larvae also increased above this rate from selenium poisoning and/or starvation. The concentration of selenium in larvae was intermediate between ryegrass roots and shoots to a maximum of 200 μg/g.

The methods of causing damage, recognition of damage, and pest status of the Australian soldier fly (Inopus rubriceps Macquart) are discussed for both crop and pasture systems, with emphasis on the current position of the soldier fly problem in New Zealand.

Significantly more Inopus rubriceps (Macquart) males fly beneath rather than above 54 cm, irrespective of crop height. In clearings fewer males were trapped at each successive height interval, namely 16–54, 82–121, and 148–186 cm above the ground. Within a 2.5-m-tall crop, no significant difference was detected in the number of males flying at the 2 higher intervals. Traps baited with virgin insects failed to attract either sex. Adult I. rubriceps were not observed to exhibit a strong color preference; but red traps caught significantly fewer flies than did traps of any other color tested. Sticky traps revealed that since the last survey, I. rubriceps had spread ca. 1.7 km into previously uninfested regions. Two species of dragon flies and 1 species of frog were found to be preying on I. rubriceps adults. 92.3% of eggs oviposited by wild females subsequently hatched. Significantly more soldier flies pupate under weeds than in soil exposed to the sun.

In New Zealand, the Australian soldier fly, Inopus rubriceps (Macquart) has two peaks of emergence and egg laying per year. The eggs are laid into pasture during late spring (November–December) and autumn (March–April) and close grazing of the sward at these times limits the recruitment of new larvae into the soil populations. Hard grazing (taking pasture to 500 kgha−1 DM standing) at the peaks of flights resulted in an estimated 75–80% control of soldier fly larvae when applied for 5 consecutive flight seasons (2.5 years). Grazing of moderate intensity (to 1000–1500 kg ha−1 DM) reduced population densities by 45–60% over the same period. The effects of close grazing on soldier fly densities were cumulative. One grazing in the week of peak flights was found to be as effective as up to four separate grazings over the extended pupation, emergence, flight, and egg laying periods. The effect of close grazing was to create unfavourable soil microclimatic conditions for egg survival in particular.

A key is given to the larval instars, of which there may be nine or more, of Inopus rubriceps (Macq.) and I. flavus (James); the key is based on setal characters and development of the cranial lobes. Characters allowing recognition and sexing of the pupae are also described.

Soldier fly (Inopus rubriceps (Macquart) adult flight activity was monitored in a trial designed to study the effect of stocking rate on soldier fly populations. Increasing the stocking rate reduced adult emergence; males were sedentary but females dispersed after laying a proportion of their eggs in the vicinity of their emergence site; and females were most active on plots grazed hard.

Inopus rubriceps (Macquart) showed greater attraction of males to purple or white than to green, red, yellow, or black. Females were attracted equally to green, yellow, white, or purple and to a lesser extent to black or red. Of the 22,331 flies caught on a 40-cm-high sticky trap during 2 annual flights, 41.1% were trapped on the first 10 cm above grass level, 29.7% on the next highest 10-cm section, 18.1% on the next higher 10-cm section, and 11.1% on the top 10-cm section. On a 370-cm-high sticky trap no male was trapped above 190 cm and the mean height of those trapped was 14.1 cm; females were caught over the entire range of the trap and the mean was 119.9 cm. Flight activity is limited by high wind speed and low Radiant Heat Load and perhaps by low light intensity.

Larvae of Inopus rubriceps (Macquart) were reared from eggs originating from spring and autumn adult emergence periods (1975–78), under both insectary and field conditions. Rate of development appeared to depend largely on temperature. Autumn-hatched larvae showed little growth for the initial 6 months, but then grew rapidly until the end of summer. Spring-hatched larvae also grew rapidly over summer, but their development slowed over winter. Year-to-year differences were found in larval survival, weight gain, and rate of development, and in subsequent adult emergence. Pest status appeared to be related to the cumulative yearly heat budget. Overall, larval survival was higher and growth and development were more rapid in the insectary than under field conditions. A male-dominant sex ratio was demonstrated.

A rapid and accurate method is described for mechanically extracting the larvae of Inopus rubriceps (Macquart) (Diptera:Strationyidae) from soil samples. The general applicability of this technique for soil fauna extraction and root washing is discussed.

Males of Inopus rubriceps (Macquart) fly near crop level in emergence areas whereas females, once mated, gain altitude on their dispersal flight. Both sexes were caught in oil-bath traps up to 54 cm above ground level, but females only were trapped at or above 83 cm. Birds and fish are Implicated in predation. The most important fish predator of I. rubriceps In the Clarence River near Hielaman Island was the clupeid Potamalosa richmondia (Macleay). None of the predators observed to date bring about much populatIOn suppression in sugarcane fields that are already infested. In the Harwood Mill area, their value lies rather in slowing down the rate of dispersion by I. rubriceps.

Ramage to ryegrass plants (Lolium × [(multiflorum × perenne) × perenne] ‘Grasslands Arinki’) by the larvae of Inopus rubriceps (Macquart) has been confirmed; from the pot work reported and related field observations, the larval level at which damage begins to become noticeable appears to be between 2000 and 3000(m2.

A new species of diapriid, Neurogalesus militis, is described from Australia and is compared with N. rubripes Dodd and N. dissimilis Dodd. It was found as a parasite of the pasture soldier fly, Inopus rubriceps (Macquart), a serious pest of sugarcane in parts of eastern Australia.

Male soldier flies, Inopus rubriceps (Macquart), were not trapped above 2.5 m, the height of an adjacent crop of sugarcane. However, female soldier flies gained considerable altitude on flights during dispersion. The maximum height recorded for a female was 8.6 m. The Welcome swallow, Hirundo neoxena Gould, was observed preying upon dispersing soldier flies above commercial sugarcane fields.