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A synoptic, annotated catalogue is provided, documenting the long history of vacillated nomenclature usages between leafhopper family-group names Gyponidae Stal 1870c and Scaridae Amyot & Serville 1843a (nec Scaridae Rafinesque 1810b), between genus-group names Gypona Germar 1821a and Scaris Le Peletier & Serville 1828a (nec Scaris Chaudoir 1879), synonyms, and use of Docalidia ferruginea (Fabricius) in the literature for Iassus ferrugineus, beginning at the formation of each taxon and ending at the present. Authors' annotations, where applicable, follow each citation. A photograph of the lectotype of Iassus ferrugineus Fabricius (Coelidiinae) and a misidentified specimen (Gyponinae) by Germar are shown for comparative purposes.

Jassus flavostriata Melichar, listed in the genera Jassus (Evans 1955: 301) and Coelidia (Metcalf (1964: 49), was overlooked in the revision of the tribe Coelidiini (Nielson 1982). The species is relegated herein to the genus Lesinda McKamey, in the tribe Equeefini sensu Theron nec tribe Coelidiini sensu Nielson, with descriptions and illustrations of the male genitalia for the first time. Lesinda Mckamey is a replacement name for Selinda Theron 1986, preoccupied by Selinda Moore 1883. Lesinda bruggeni (Theron) is herein new combination for Selinda bruggeni Theron. A male syntype specimen, Jassus flavostriatus Melichar, is herein designated lectotype.

A new genus, Paradicodia, type species, Paradicodia eminentia, sp. nov. and 22 new species in ten genera and four tribes in the subfamily Coelidiinae from Peru are elucidated. These include the following: Paradicodia eminentia, P. bispiculata, P. lineata, Evansolidia semibulbata, Crassinolanus bulbatus, Dialodia undulata, (Coelidiini); Stalolidia prodignatia, Stalolidia oblongata, Hastalidia retrorsa, Docalidia multipenna, D. acinacea, D. unica, D. lunata, D. ata, D. soulierae, D. rodriguezi, D. trispinata, D. quadrata, D. vansweringeni (Teruliini); Sandersellus flexus (Sandersellini); Youngolidia undulata and Y. bifurcata (Youngolidiini). New records for Peru include the following species: Docalidia dentula (Metcalf), Dicodia germari Nielson, Megalidia elongata Nielson and Boliviela inflata (DeLong).

In this revision, 19 major characters with 149 attendant character states among a maximum of 324 exemplars (genera and species) of 11 tribes assigned in the leafhopper subfamily Coelidiinae sensu lato are described, assessed and collated. All taxa were evaluated for their delineating taxonomic features. Results of these assessments are provided for the following taxonomic groups: tribes, type-genera, type-species and numerous supplemental genera and species across six biogeographical regions. A history of nomenclature usages and classifications are given to document the unstable systematics that has been nearly continuous from the time of inception to the present. A historical review of phylogeny of the subfamily Coelidiinae sensu lato is also provided.A combined total of 74 character states delineated tribes in Coelidiinae sensu stricto from Macroceratogoniini sensu Dietrich and Equeefini sensu Theron and from each other. Twenty character states delineated Macroceratogoniini and tribes in Coelidiinae sensu stricto from each other. Twenty character states delineated Equeefini and tribes in Coelidiinae sensu stricto from each other. Twenty-one character states delineated Macroceratogoniini and Equeefini from each other. Thirteen character states delineated tribes in Coelidiinae sensu stricto from Macroceratogoniini + Equeefini and from each other. Tribes in Coelidiinae sensu stricto shared fewer diagnostic states with Macroceratogoniini (36%) than with Equeefini (76%), suggesting that tribes of Coelidiinae sensu stricto are collectively farther removed taxonomically and phylogenetically from Macroceratogoniini than they are from Equeefini.Nine tribes originally assigned in Coelidiinae by the author are retained. Reassignment of Equeefini to Deltocephalinae is proposed. Provisional reassignment of Macroceratogoniini to Evacanthinae (=Nirvaninae) is proposed in view of its explicit delineation from tribes of Coelidiinae, sensu stricto. Lesinda McKamey formerly assigned in tribe Equeefini in Coelidiinae sensu lato is relegated herein to tribe Equeefini in Deltocephalinae. Gariesa Theron 1986b: 153 is a junior synonym of Mgenia Theron 1984a: 313 in the tribe Equeefini. Thagria triuncula Nielson is a replacement name for Thagria bidentata Xu & Kuoh from China, nec Thagria bidentata Nielson from Malaysia. The identity of the type-species of Coelidia Germar, Coelidia venosa Germar, is clarified with photos and comments. The dorsal connective of the aedeagus, applied previously to Coelidiinae sensu stricto, is redefined and renamed dorsal preatrial aedeagal apodeme. The phylogeny of the family Cicadellidae and particularly the subfamily Coelidiinae sensu lato remains unclear. It is proposed that the number of exemplars (genera and species) and character states be substantially increased in future analyses. Moreover, only known, monophyletic exemplars (genera) are recommended to avoid problematic, inferred phylogenetic relationship among tested family-group taxa.

A new genus, Fibragallia, type-species Agallia bidigitata Oman. is established for the Agallia bidigitata species group. Seven new species in the complex are described and illustrated: F. tridigitata from Panama, mexicana from Mexico and paradigitata, similis, grandigitata, lamina, and biclava from Costa Rica. Diagnostic characters in the female seventh sternum are elucidated. Fibragallia bidigitata (Oman) is designated as a new combination. A key to species, a discussion of generic relationships and distribution of the genus and species complex are presented.

Two new species of the genus Brasa, B. dozieri and B. media, are described and illustrated. The identity of the type-species of Brasa, Macropsis rugicollis Dozier, is clarified, with a redescription and illustrations of the male genital characters. A key to species and distribution of the genus are also given.

The following 21 new species of Thagria from the Oriental and Australian regions are described, illustrated and photographed: T. aenigmatis, sp. nov., T. asperitas sp. nov., T. biretrorsa sp. nov., T. colorata, sp. nov., T. coniunctionis, sp. nov., T. constanti, sp.nov., T. fidelitas sp. nov., T. freytagi sp. nov., T. intorta sp. nov., T. iuxta, sp. nov., T. lobata sp. nov., T. longicatilla sp. nov., T. malenovskyi sp. nov., T. oldfieldi, sp. nov., T. paraunca, sp. nov., T. quadrimaculata, sp. nov., T. quadrispinosa sp. nov., T. trimaculata sp. nov., T. unibasispinosa, sp. nov.; T. unica sp. nov. and T. viraktamathi, sp. nov. Thagria bidentata XuKuoh 1998, preoccupied by Thagria bidentata Nielson 1982 is renamed herein Thagria xui nom. nov. Thagria multicalcara Nielson is suppressed junior synonym of Coelidia inscripta Walker. Thagria hongdoensis KwonLee is suppressed junior synonym of resurrected Coelidia satsumensis Matsumura. Cambodia is a new record for T. longistyla Freytag. Laos is a new record for T. acrodens Freytag, T. boulardi Nielson, T.emeiensis Zhang, T. fuscoscuta Zhang, T. janssoni Nielson, T. obrienae Nielson and T. ungulata Nielson. Vietnam is a new record for T. grandis Nielson and T. marissae Nielson. Intra-inter specific variation involving 6 closely related species (melichari species complex) in Southeast Asia is discussed. Morphology and taxonomic value of the dorsal connective, revised key to species and genera in Thagriini and an updated synoptic catalogue of the genus are also presented. Problematical species in the genus Thagria are reviewed. Distribution of 235 known species and the relationship between clypellus configuration and geographical origin are given.

Two new species in the tribe Coelidiini from southern China are described and illustrated. These include Taharana zhangi and Lodiana recurvata, all from Yunnan province.

The circumscription and morphological characterization of the deltocephaline tribe Acostemmini is revised based on dis-coveries of new and poorly known taxa from recent collections in Madagascar and from examination of the type speci-mens of Alocoelidia fulva Evans, Iturnoria insulana Evans, and Protonesis delegorguei Spinola. Alocoelidia Evans 1954, Caelidioides Signoret 1880, Iturnoria Evans 1954, and Protonesis Spinola 1850 were previously placed in Coelidiinaebut were later removed from the subfamily and until now have been unplaced to subfamily are placed here in Deltocepha-linae: Acostemmini, new placement. A new genus and species, Ikelibeloha cristata gen. n., sp. n., are described that havean unusually modified structure of the head and a large, crested pronotum. Molecular data (28S, Histone H3 genes) wereobtained for Ikelibeloha and Iturnoria, and analyzed with other members of Deltocephalinae. Results of the phylogeneticanalyses show strong support for the monophyletic clade ((Acostemma, Eryapus), (Ikelibeloha, Iturnoria)) and thus a re-lationship between previously described Acostemmini, Ikelibeloha, and Iturnoria has strong statistical support, and aclose relationship is inferred between these and the morphologically similar Alocoelidia, Caelidioides, and Protonesis. Two new species of Alocoelidia, A. maurae sp. n. and A. chasei sp. n. are described, and the genus is redescribed. Themale genitalia of Caelidioides tristis (Signoret), Iturnoria insulana, Alocoelidia fulva, and Acostemella rubra Evans areillustrated and described for the first time. The female genitalia of A. fulva, C. tristis and I. insulana are described and thefirst and second valvulae of C. tristis are illustrated. The habitus and face of Protonesis delegorguei are illustrated and thegenus is redescribed. The characters traditionally used to define Acostemmini are reviewed with notes on their known de-grees of variation, and characters that differentiate Acostemmini from the closely related tribe Stegelytrini are discussed.The type of Malagasiella minima Evans was also examined, and Malagasiella Evans, 1954 is considered a junior syn-onym of Doratulina Melichar, 1903 (Deltocephalinae: Stenometopiini), syn. n. giving the new combination Doratulina minima (Evans) comb. n.

Alfalfa, Medicago salim L., cultivars ‘Lahontan,’ ‘Hayden,’ ‘UC Cargo,’ and ‘Caliverde 65’ were screened and evaluated for resistance to biotypes Band H of the spotted alfalfa aphid (SAA), Therioaphis maculata (Buckton) (Homoptera: Aphididae). Surviving plants screened by biotype B or H were evaluated simultaneously for resistance to both biotypes, then were rated by their response to each biotype. There was a significant differential resistance to biotype B among cultivars screened by biotype B. Some of these plants in each cultivar were resistant to biotype H, thus showing combined resistance to both biotypes. These results suggested there was a number of selected plants from each cultivar that expressed genes for horizontal resistance. There was no differential resistance to biotype H among cultivars that had been screened by biotype H, but all surviving plants resistant to biotype H also were resistant to biotype B. Screening by biotype H detected significantly more ‘Lahontan’ plants having combined resistance than did screening by biotype B. Vertical resistance to SAA was demonstrated in the cultivars ‘Moapa,’ ‘Moapa 69,’ ‘Sonora,’ ‘Sonora 70,’ ‘Mesa-Sirsa,’ and experimental-line MSTT. Horizontal resistance to five SAA biotypes was demonstrated in three parent clones and in ca. 17% of the progeny of ‘Lahontan.’ We found an indication of horizontal resistance in ‘Mesa-Sirsa’ and MSTT.

The probing behavior of four biotypes of the spotted alfalfa aphid, Therioaphis maculata (Buckton), feeding on resistant and susceptible alfalfa clones (genotypes) was investigated. Salivation, X-pattern, and ingestion waveforms, and probing sequences were similar among four biotypes probing the substrate of a susceptible clone. On one resistant clone (‘Moapa’ C-905) probing sequences produced by biotypes A and C were similar but abnormal; stylet penetration of the phloem sieve element and ingestion were lacking or greatly suppressed. On another resistant clone (Moapa C-908) probing sequences produced by biotype A were normal whereas those produced by biotype C were abnormal; stylet penetration of phloem sieve elements and ingestion were completely lacking. The salivation probe was successfully completed by both biotypes on the resistant clones; salivation time was significantly longer on the resistant clone than on the susceptible clone. The data suggest that the mechanism of resistance is based on a chemical interaction between the plant and aphid, and that the system is related to the phytoalexin theory of host-plant resistance and to the phenol-phenolase reactions of plants and sap-sucking insects. Zusammenfassung PROBEVERHALTEN VON BIOTYPEN DER LUZERNEZIERLAUS AN RESISTENTEN UND ANFALLIGEN LUZERNEKLONEN Untersucht wurde das Probeverhalten von vier Biotypen der Luzernezierlaus (Therioaphis maculata (Buckton)) an resistenten und anfalligen Luzerneklonen (Genotypen) mit Hilfe der McLean-schen elektronischen Messung. Dabei wurden die drei Wellenformen (1) fur Speichelfluss, (2) fur das Eindringen in ein Siebelement (= X-pattern) und (3) fur die Nahrungsaufnahme graphoanalytisch aufgenommen und analysiert. Auf anfalligen Klonen war das Probeverhalten, gemessen an Form und Abfolge von (1)–(3) bei allen Biotypen gleichartig. Dagegen waren auf einem resistenten Klon („Moapa” C-905) die Probestiche der A- und C-Biotypen zwar ahnlich aber anormal: Stechborstenpenetration in das Siebelement und Nahrungsaufnahme daraus waren stark gehemmt bzw. fehlten. Bei einem anderen resistenten Klon („Moapa” C-908) waren die Probestiche des A-Biotypus normal, wahrend die des C-Biotypus anormal waren; beim letzteren unterblieben Stechborstenpenetration in das Siebelement und Nahrungsaufnahme vollstandig. Bei beiden Biotypen lief die Speichelflussphase auf resistenten Klonen erfolgreich ab; die Dauer des Speichelflusses war dabei auf resistenten Klonen bedeutend langer als auf anfalligen. Die Daten weisen darauf hin, dass der Resistenzmechanismus auf einer chemischen Interaktion zwischen Wirtspflanze und Blattlaus beruht und dass dieser Mechanismus in Zusammenhang gebracht werden kann mit der Phytoalexintheorie uber die Resistenz der Wirtspflanze und mit den Phenol-Phenolasereaktionen zwischen Pflanzen und saftsaugenden Insekten.

A study of the genus Colladonus and related genera of Mexico and Central America was based almost exclusively upon the examination of nearly the entire type series of all the Idiodonus species described by the late Dr. D. M. DeLong. All species referable to Colladonus are redescribed, and illustrations of the male genitalia are given for the first time. A key to the species of Mexico and Central America is also included. A brief discussion of the distribution and phylogeny of the group is given. Among 35 species described by DeLong in Idiodonus , 21 belong in Colladonus, 1 is assigned to Ollarianus Ball , 1 to Paratanus Young , 2 to Bonneyana Oman , 2 are retained in Idiodonus , 5 are relegated to four proposed new genera, and the remaining 3 have uncertain generic position. One new combination in Colladonus is proposed, and 16 names are treated as new synonyms. Eight new combinations are proposed in the treatment of related genera. New genera include: Paracolladonus, Paracrassana, Paranurenus , and Jaacunga . The subgenus Angulanus DeLong is elevated to generic rank.

Six biotypes of Therioaphis maculata (Buckton) have now been recognized in western United States. Among these, four are recent discoveries and were identified from results of a combination of studies including tests on the parent clones of ‘Moapa’ and ‘Washoe’ alfalfa, Medicago saliva L., biological activity, and response to sonic organophosphate insecticides. The new biotypes have been designated ENT-C, ENT-D, ENT-E, and ENT-F.

Colladonus aflexus (California), C. arcanus (Wyoming), C. olus (Michigan), C. parvus (Wyoming), and C. peayi (California) are described and illustrated.

When the biology of Colladonus geminatus (Van Duzee) was studied at The Dalles, Oregon in 1952–53, the life cycle from egg to adult was found to average 52 clays in the insectary and 65–75 days in the field. Leafhoppers overwintered as eggs in alfalfa foliage and completed 2 generations a year on alfalfa, the preferred host. Spring populations were produced almost exclusively from dry-land alfalfa and fall populations from irrigated alfalfa. Leafhoppers were most abundant on alfalfa in May and September and in orchards in late May or early June, and in November. In both locations, populations were much higher in the fall, and a marked decrease occurred as distance from cultivated regions increased. Leafhoppers moved from breeding hosts (mainly alfalfa) into orchards during the spring and fall. Males comprised more than 75% of the trapped population except in July and October, when females dominated by from 2:1 to 3:1. Heaviest flights of leafhoppers occurred when the temperature was above 50°F and wind movement was less than 3 mph. Dissemination was reduced when the wind velocity was greater and was completely suppressed at 12 mph. Populations decreased in geometrical proportion to height above ground, and heaviest flights were recorded at 6 feet above ground.

Alfalfa varieties— Medicago spp.—experimental lines, and individual plants were evaluated and tested for resistance to the alfalfa seed chalcid, Bruchophagus roddi Gussakovskii, in Arizona from 1958 to 1963. Among the varieties tested, Lahontan performed well in nearly all tests and is considered a good source for selecting resistant plants. Others were Hairy Peruvian, Zia, Ranger, and A-224. Several entries from foreign countries also performed well. Among the species tested, Medicago tianschanica Vass. var. agropyretorum Vass. was the most promising entry. Tests on individual clones indicated that C-89 from Lahontan and M-56-11 and other plants from Sirsa no. 9 were also good sources of chalcid resistance

Except for the south-European “ Mesodicus” foveolatus Fieber, 1866, here treated as incertae sedis pending examination of the type, the genus Xerophloea Germar, 1839, is Neogeic in its distribution. Of the 27 nominal species that have been placed in Xerophloea , 13 are recognized as valid and are keyed, with descriptions, geographic distributions, and illustrations. These 13 are separated primarily on the basis of a broad concept of geographic distribution, associated with the relation between interocular width and median length of crown. Xerophloea peltata (Uhler), previously confused with X. viridis (Fabr.), is resurrected from synonymy, and X. carinata var. gigas Oman is elevated to specific status. New synonymy: X. breviceps Osborn (= X. carinata Oman), X. robusta Lawson (= X. inflata Lawson), Ar. viridis (Fabr.) (= X. minor Lawson and X. oraclis Lawson), and X. peltata (Uhler) (= X. zionis Lawson, X. vanduzeei Lawson, X. obtusa Lawson, X. californica Lawson, X. brunnea Lawson, and X. tenuata Lawson).d

Following the introduction of the spotted alfalfa aphid, Theriotiphis maculata (Buckton), in Arizona, an 87% reduction in its population occurred from 1955 to the end of 1959. Many factors were responsible. Of these, the specific effects of rainfall and temperature are discussed. Population peaks were frequent and usually occurred in April, July, and October. Rainfall was detrimental to the aphid population if a sufficient amount fell just prior to the expected buildup to initiate epizootic outbreaks of a fungus. Dates of population peaks were dependent upon temperature and relative humidity.

Fifty-two experimental alfalfas and cultivars were evaluated for resistance to 4 biotypes (ENT-A, ENT-C, ENT-E, ENT-F) of Therioaphis maculate (Buckton) in greenhouse tests at Tucson, Arizona. Three alfalfas (‘Caliverde’ 65, developed by the University of California at Davis; T-3-12, a new experimental developed jointly by the University of Arizona and Entomology Research Division, ARS, USDA; and UC-64, a new experimental developed jointly by University of California and Entomology Research Division, ARS, USDA) were rated highly resistant, 14 moderately resistant, 13 intermediate, 7 low resistant, 9 susceptible, and 6 highly susceptible. In the analyses, highly significant differences were found in seedling survival. Also, differences among biotypes were highly significant, and the biotypes reacted differentially among and within alfalfas, thus substantiating previous experiments that they are distinct. When the virulence of biotypes was established, ENT-F was found to be the most virulent strain, followed by ENT-E, ENT-A, and ENT-C.

Studies on the biology of Collops vittatus (Say) were undertaken in the laboratory and field at Tempe, Ariz., from June 15 to September 15, 1957. On an average 78 days were required for development from egg to adult. Additional data on longevity and feeding capacity of C. vittatus in relation to temperature are given. Observations on the feeding habits of seven predators of the spotted alfalfa aphirl (Therioaphis maculate (Buckton)) indicated that the average number of aphids destroyed per adult per day by hippodamia convergens G.-M. was 97, Collops vittatus (Say) 35, Zelus renardii Kolenati 34, Geocoris punctipes sonoraensis Van Duzee 29, Sinea confuse Caudell 24, Nabis ferus (L.) 22, and Orius tristicoler (White) 5. The effect of sex and different feeding periods on the feeding capacity of the various predators is also given.

From 1959 to 1961 at Mesa, Arizona, numerous alfalfas were assessed for their performance when exposed to populations of the pea aphid, Acyrthosiphon pisum (Harris), thrips (mainly Frankliniella spp.), leafhoppers (mainly Aceratagallia curvata Oman and Beamer), the three-cornered alfalfa hopper, Spissistilus festinus (Say), and lygus bugs (principally Lygus Hesperus Knight). Although none of the alfalfas showed strong indications of resistance to these insects, several apparently have sufficient resistance to serve as sources for selection. The most promising alfalfas for three-cornered alfalfa hopper resistance were Chilean 21–5, Kansas 67–1108, and Sirsa #9; for pea aphid resistance, Doehnefeldt, Du Puits, Socheville Brand, and North Carolina Synthetic G3; and for lygus bug resistance, Zia, Rhizoma, and Stoneville Polycross No. 1. Significant differences among alfalfas in leahopper or thrips populations were not obtained.

Oncometopia alpha Fowler, a large, rare, univoltine leafhopper species in Arizona, requires 73–87 days for development from egg to adult in the greenhouse. Mean development time in an environmental chamber was 111 days at a mean temperature of 24°C. Adults fed exclusively from the xylem of broadbean plants laid eggs in clutches in leaf tissue, and lived 8–10 months. Adults overwintered on woody dicots such as Salix sp. and Populus fremontii S. Wats, and had a reproductive diapause period for ca. 6 months from July to January.

The development of Cuerna arida Oman and Beamer (69.8 days) and of C. balli Oman and Beamer (70.6 days) from egg to adult was similar in the laboratory on a grass host, Panicum antidotale Retz. However, the intact stems were more favorable for development of arida ; excised leaves were more favorable for balli . Field and greenhouse studies suggest that both species are bivoltine; hosts are believed to be perennial grasses. The northern range of the more common species arida overlaps the southern range of balli . The 2 species did not interbreed in captivity.

Acyrthosiphon kondoi Shinji did not produce sexual forms when reared under controlled conditions of 15 combinations of temperature and photoperiod. Apterae were predominantly produced at higher temperatures (20° and 25° C) at all photoperiods (8-, 12-, and 16-h photophase/24 h) except at 25° C/8-h photophase when alatae were produced. Low temperatures (10° and 15° C) generally caused alatae to be produced except at 15° C/8-h photophase when apterae were predominantly produced. The aphid switched from the production of one alary morph early in the reproductive period to the production of the opposite morph later in the reproductive period at all temperature/photoperiod regimes except 20°/16 h when no switching occured. The cause of form switching was not attributable to temperature or photoperiod, but is believed to be an inherent biological phenemenon associated with survival mechanisms.

A new virulent biotype of Therioaphis maculata (Buckton) was collected from populations infesting ‘Mesa-Sirsa’ alfalfa at Mesa and Poston, AZ. The new strain, designated H, and biotype F, reproduced and survived on 6 of 9 parent clones of ‘Moapa’ alfalfa. Clone C-907 was susceptible to H and resistant to F, clearly separating the 2 closely related biotypes. Both biotypes were identically susceptible to 4 organophosphate insecticides.

Ovipositional and olfactory behavior of Bruchophagus roddi (Gussakovsky) was studied on resistant and susceptible alfalfa clones. Seed pods of the resistant clone were ovipositionally nonpreferred for 8 days (ages 10–18) vs. 2 days (ages 8–10) in the susceptible clone when caged with 2 ♀ /seed. At a density of 1 ♀/seed, 8-, to 10-day-old seed pods of the resistant clone were nonpreferred. An unidentified olfactory attractant, detected in 10-, to 14-day-old seed pods of the susceptible clone, probably mediated orientation to seed pods and initiation of egg laying.

The interaction between virulence in Therioaphis maculata (Buckton) and resistance in ‘Hayden’ and ‘Lahontan’ alfalfas was investigated. Evidence of a gene for gene relationship was found between biotypes (C, A, E, F, H) of the spotted alfalfa aphid expressing genes for virulence and in plants selected from Hayden expressing corresponding genes for resistance. This relationship was not evident between these same biotypes and plants selected from Lahontan alfalfa. The relationship in Hayden appears to be oligogenic (specific) since resistance to avirulent biotypes was not conferred in plants to virulent biotypes. The genic system in Lahontan was unusual and may be polygenic or oligogenic (general) since all plants selected for resistance to avirulent biotypes were equally resistant to virulent biotypes and vice versa. Lahontan alfalfa should be fully exploited so that these traits can be incorporated into alfalfa cultivars where polygenic resistance to the spotted alfalfa aphid is desired.

The developmental biology of Scaphytopius nitridus DeLong, a vector of Spiroplasma citri, the causative organism of stubborn disease of citrus in California and Arizona, was studied in the greenhouse. Nymphs required 40.02 days or 15,460 heat units to complete development. The mean number of nymphs produced per female was 113.6; the maximum was 353. Adults produced progeny up to 77 days and lived as long as 156 days. Population of S. nitridus and S. californiensis Hepner failed to interbreed, indicating that the two species are distinct. New distribution and host records are provided.

In studies on the reaction of seedling alfalfa to feeding of the spotted alfalfa aphid, Therioaphis (Pterocallidium) maculata (Buckton), in southern Arizona, the rate of plant destruction was in inverse geometrical proportion to the number of aphids. One aphid per plant feeding and multiplying under uncontrolled conditions killed plants in approximately 12 days. The threshold period varied under both conditions, but the range was much greater when the population was controlled. The resistance differential was constant under uncontrolled conditions but varied greatly when the population was controlled. Damage to plants consisted of yellow vein clearing, chlorotic mottling, wilting, and finally death.

In studies conducted in a lath house at Mesa, Arizona, in 1960 the population density of leafhoppers, Aceratagallia curvata Oman, per plant ranged from 2 to 14 males, females, and sexes combined. Seedling mortality was greatest during the first 5 days of the testing. Mortality owing to direct insect feeding decreased, arithmetically from males to females to sexes combined. Seedling longevity was inverse geometrical proportion to the number of male and female leafhoppers feeding separately on plants and in inverse arithmetical proportion when the sexes were combined. Longevity of seedlings ranged from 17.5 to 1.5 days as a result of feeding from 2 to 14 leafhoppers per plant, respectively.

Observations on the biology of Acinopterus angulatus Lawson and Aceratagallia curvata Oman were made in the greenhouse between June 1964 and March 1965 at Mesa, Arizona. For angulatus, the period from egg to adult averaged 41.5 days. The production of nymphs averaged 224.3 for once-mated females and 188.1 for multiple-mated females. The greatest number of nymphs produced by a female was 621. Longevity of once-mated females averaged 68.2 days, but females caged continuously with a male lived an average of only 45.2 days. For curvata, the period from egg to adult averaged 31.5 days. The production of nymphs averaged 64.1. The greatest number of nymphs produced by a female was 113. Longevity of females averaged 107.7 days; that of males averaged 121.4. Measurements were made of eggs, nymphal instars, and adults of both species.

Laboratory studies 011 the biology of the convergent lady beetle ( Hippodamia convergens G.-M.), when fed spotted alfalfa aphids ( Therioaphis maculata (Buckton)), showed that the incubation period of the egg averaged 2.0 days, the larval stage 7.6 days, the pupal stage 4.1 days and the period from egg to adult 13.8 days. There were four larval instars. Daily consumption of aphids per instar was in direct arithmetical proportion and total consumption in direct geometrical proportion to the larval in-star. When reared in the laboratory adult males lived longest on a diet of 60 and females on 90 aphids per day, whereas field-collected adults of both sexes lived longest on 30 aphids per day. Most laboratory-reared adults lived longer than field-collected adults. Females from both sources generally lived longer than males. The length of the immature stages was shorter and daily aphid consumption higher than when other aphids were used as the diet.

Four populations of Acyrthosiphon pisum (Harris) from 4 geographical areas in the western United States—Bakersfield, Calif, Mesa, Ariz.: Corvallis, Oreg.; and Reno, Nev.,—were segregated on the basis of biological response to 4 different temperatures. Effect of temperature on all biological activities of each aphid biotype and differences in the mean development of the 1st-nymphal stadium and combined nymphal stadia were highly significant among biotypes. Fecundity among all biotypes was different at the 0.01 level of probability. A highly significant biotype by temperature interaction was found for development of the 1st instar stage and the preparturition period. Populations from Bakersfield and Mesa had similar but a significantly reduced development of the 1st instar stage than populations from Reno and Corvallis. However, populations from Reno and Mesa bad a similar but a significantly higher fecundity than populations from Bakersfield and Corvallis.

A new experimental alfalfa, CUF-101, has been successfully developed that is resistant to 3 species of aphids, Acyrthosiphon kondoi Shinji, the pea aphid, A. pisum (Harris), and the spotted alfalfa aphid. Therioaphis maculate (Buckton). In greenhouse tests, 70.3, 71.0, and 87.3% of CUF-101 seedlings survived infestation to 3 aphid species, respectively, compared with 70.3, 85.6, and 93.3% of the resistant checks.

Growth and development of Bruchophagus roddi (Gussakovsky) were studied using resistant and susceptible clones of alfalfa, Medicago sativa L. Developmental times for 5 stages (egg incubation, undefecated larva, defecated larva, pupa, emerging adult) were not significantly different between the 2 clones. Differences between alones for developmental mortality, adult longevity, and total life span also were nonsignificant. Thus, the resistant clone did not express antibiosis to the seed chalcid, and ovipositional nonpreference appears to be the sole operating mechanism of resistance to the alfalfa seed chalcid in the clones studied.