Laboratory and experimental studies of four of the five subspecies of Euxoa comosa (Morr.), i.e. annir, altera, lutulenta and Ontario, each formerly considered of specific rank, were undertaken to assess their taxonomic status. Morphologically the immature stages of the subspecies are similar although lutulenta has a 40–50% larger egg and the larvae of lutulenta and Ontario are darker than those of annir and altera. The subspecies show differentiation in larval growth rate, number of larval instars, duration of preimaginal development and length of the preoviposition period. The possible adaptive significance of these differences are discussed. Hybrid F1 were obtained from 11 of the 12 possible pairwise combinations. Eight of the F1 hybrids were inbred and six produced fertile eggs. Some of the F2 progenies exhibited a wide range of phenotypes encompassing all subspecies including those of the 5th subspecies, E. c. comosa. Although hybridization success was high there was some evidence of genetic incompatibility including dyssynchronous emergence of the sexes and the absence, shortage, or inviability of female moths in some crosses. Mating discrimination tests show a moderate level of mating bias between subspecies. Calling periods of females of the subspecies largely overlap although differences in the time at which calling begins might be responsible for some of the mating bias. Both laboratory and field tests of sex pheromone attraction indicate considerable sex pheromone specificity among the subspecies. The results are discussed with reference to a companion paper which on the basis of conventional taxonomic characters and biogeographic considerations concludes that Euxoa comosa is best regarded as a polytypic species encompassing five subspecies.

The North American species of the genus Acidota Stephens are revised. Three species are recognized, the Holarctic species quadrata (Zetterstedt) and crenata (Fabricius) and the eastern North American species subcarinata Erichson. All major generic and specific characters are illustrated with line drawings and scanning electron photomicrographs. A key is included to aid in identifying the species. Olophrum crenulatum Hatch is placed in synonymy with A. quadrata.

The identities of the 12 previously described species of Neosilba McAlpine, seven of which are represented among the syntypes of pendula (Bezzi), are established: batesi (Curran), certa (Walker), dimidiata (Curran), fuscipennis (Curran), glaberrima (Wiedemann), longicerata (Hennig), major (Malloch) [(= magna (Hennig), new synonymy], parva (Hennig), pendula (Bezzi), perezi (Romero S. and Ruppel), and pseudopendula (Korytkowski and Ojeda). Three new species, also represented among the syntypes of pendula, are described: oaxacana and peltae from Mexico, and zadolicha from Colombia and Brazil. Lectotypes are designated for magna, parva, pendula, and perezi. “Carpolonchaea” devions Hennig is placed in Silba Macquart, and “Carpolonchaea” intermedia Hennig is transferred to Lonchaea Fallen (new combination). New keys to the world genera of Lonchaeidae and to all described species of Neosilba are provided. Fifty-four illustrations, mostly of male and female terminalia, are given.

A protease digestion technique for preparing insect chemosensilla for observation at high magnifications under the Scanning Electron Microscope is described. Treatment with protease for 30 min or more followed by sonication removes material normally obscuring pores and surface grooves. This allows surface details and terminal valves to be seen under the SEM. The chemoreceptive hairs of insects can now be rapidly classified as having primarily a contact or olfactory function based on the presence or absence of visible terminal openings on some of the sensilla. Trypsin treatment was less useful, and neuraminidase had little effect. These results indicate that the material extruded onto the surface of the sensillum is proteinaceous.

Laboratory tests showed that nymphs of the migratory grasshopper are very sensitive to diflubenzuron (Dimilin) when reared continuously on treated wheat seedlings or artificial diet and fresh lettuce. At concentrations of 10 ppm or above, diflubenzuron completely inhibited moulting of 2nd-instar nymphs. With continuous exposure on treated wheat seedlings, the LC90 values after 8, 12 and 20 days were 10.0, 2.4 and 0.8 ppm, respectively. Comparable values were obtained with the artificial diet and lettuce. However, when 2nd instars were placed on diflubenzuron-treated wheat foliage for 1 day then transferred onto untreated plants, toxicity declined markedly.

Although the toxic effects of diflubenzuron were delayed, dry weight determinations on wheat seedlings indicated that nymphal feeding damage was insignificant if the plants had been sprayed with 10 ppm diflubenzuron.

The implications of these findings are discussed in terms of the potential field use of diflubenzuron against stationary and mobile grasshopper nymphs.

Linolenic acid, added to a defatted diet in which wheast and alfalfa meal were the only protein sources, optimally reduced wing syndrome (defined as crumpled wings) in Mamestra brassica Walker at 1.1 mg/g (w/w dry wt.) of diet, increased survival to pupa at 2.2 mg/g, and reduced pupal syndrome (defined as improper formation of the 4th abdominal sternite) and increased survival to adult at 5.8 mg/g. Pupal weight increased and incidence of diapause decreased as dietary linolenic acid increased. Linoleic acid substituted for linolenic acid only in survival to the pupal stage. Pupae from larvae fed artificial diets had more fat (20.6–25.5% dry wt.) than pupae from larvae fed rape leaves (16.5%). Absolute levels of linolenic acid increased in pupae in proportion to dietary levels including pupae from larvae reared on rape leaves but the relative amount of linolenic acid sequestered in pupae from leaf-fed larvae was greater.

Pupal syndrome is a sensitive indicator of dietary adequacy and its occurrence is affected by dietary linolenic acid and possibly other fat soluble components.

Frurtienta nundinella (Zeller), a moth attacking horsenettle (Solanum carolinense L.) in southwest Virginia, has two generations per year. Overwintering adults oviposited on tips of emerging horsenettle shoots in late May. First generation larvae fed on terminal growth points in mid-June; each was enclosed in a characteristic tight hollow chamber formed from leaves. Pupation occurred in mid-June through July and adults emerged from late June to early August. Larvae of the second generation attacked fruits. A single larva was capable of destroying all the seeds within a berry. Second generation larvae pupated inside the berries, emerging as adults between late August and late September. Early stages of infestation of berries were not easily detected until the larvae had reached 4th instar when the infested berries had a characteristic appearance. Just before the full grown larvae pupated, they formed exit holes covered only by thin membrane in the berries. Although damage to the plants resulted from both modes of. feeding, the infestation rate was low as infested plants were frequently in small isolated patches. Life cycle of the moth from egg to adult was about 50 days per generation.

Five trap designs were evaluated for sampling the insect complex attracted to severed shortleaf (Pinus echinata Mill.), Virginia (P. virginiana Mill.), and loblolly (P. taeda L.) pines. The baffled flight trap was superior for capturing Coleoptera. Plexiglas®, saran screen, and 4-directional Plexiglas traps were most efficient in trapping Diptera and Hymenoptera. The results indicate that the choice of any particular trap depends on the group of insects to be sampled.

Mites, ticks, and fleas were removed from the fur of 110 specimens of Zapus hudsonius (Zimmermann) from Prince Edward Island, coastal New Brunswick, and northern Nova Scotia. The species which were most abundant and the only ones which occurred on these mice throughout the area were Dermacarus newyorkensis, Neotrombicula harperi, Androlaelaps fahrenholzi, and Ixodes muris. Also examined were 47 specimens of Napaeozapus insignis (Miller) from the above provinces plus Gaspé Peninsula, Quebec. Dermacarus newyorkensis and Neotrombicula harperi were the most abundant ectoparasites. Neotrombicula harperi was the only ectoparasite which occurred on N. insignis throughout the region.

Starved M. corollae Fab. larvae captured prey more quickly than unstarved larvae and older larvae, except those approaching pupation, sooner than younger larvae. Generally, older larvae also consumed prey more quickly but starvation increased prey handling time because starved larvae extracted 43% more, on average, from prey before discarding them. Significance of these findings for survival of M. corollae is discussed.

Field tests were conducted annually near Delhi, Ontario from 1977 to 1981 to evaluate blacklight and sex attractant traps for monitoring adult populations of the darksided cutworm, Euxoa messoria (Harris), in the major tobacco-producing area. There were no significant differences between the catches of sex attractant traps set at 1.0 m and 0.5 m above ground level. Sex attractant traps were superior to blacklight traps for monitoring populations of this pest species. There was a variation in abundance from year to year, but the time of peak occurrence of E. messoria adults was the same in each of the 5 years.

Seven years of field evaluation has shown the alfalfa blotch leafminer, Agromyza frontella (Rondani), to be of minor economic importance in Vermont. Although response to certain insecticidal treatments resulted in highly significant reduction in leaf mining at time of cut, no other differences were shown. Analyses of fiber content as measured by lignin, cell wall constituents, acid detergent fiber, quality as measured by % protein and % digestibility, and yields in dry weight (kg/ha) showed no significant differences. Comparison of leaflet dehiscence from field-cured and baled samples failed to indicate differences between blotched and healthy alfalfa.

Two imported parasite species, Chrysocharis punctifacies Delucchi and Dacnusa dryas (Nixon), are established within the state; we predict that these parasites combined with native species will effect a decline in alfalfa blotch leafminer levels below any conceivable economic threshold.

Within individual trees in an 8-year-old provenance planting of ponderosa pine (Pinus ponderosa var. scopulorum Engelm.) in central Nebraska, the infestation of tips by the western pine tip moth (Rhyacionia bushnelli Busck) generally decreased with increasing tree height and varied with whorl and seed source. Trees from Eastern Plains sources were taller and had fewer infestations than trees from three other geographic regions. Sampling tips on whorls 3 through 6, 4 through 6, or 4 through 7 all give an accurate estimate of damaged tips per tree in trees less than or equal to 3.0 m high.

Selective predation (i.e., non-random feeding) was studied in a laboratory system that allowed individual lycosid spiders, Pardosa vancouveri, to feed on prey populations consisting of one or two kinds of insects. Various combinations of male and female fruit flies (Drosophila melanogaster), “small” and “large” beetle larvae (Tenebrio molitor), and nymphal milkweed bugs (Oncopeltus fasciatus) were used as prey. Female adult and subadult spiders were used as predators. Generally, fruit flies were selected by the spiders over mealworms or milkweed bugs, and small mealworms over large ones. No selection occurred between male and female flies. Very weak or no selection occurred between small beetle larvae and milkweed bugs. Spiders of both age classes showed similar selective tendencies. Prior feeding experiences did not alter feeding selections, but minor changes in the physical complexity of the environment did. Twelve criteria related to development, survival, growth, and fecundity were monitored for 12 groups of spiders fed either single or two-prey combinations of the five kinds of prey. The hierarchy of benefits conferred by the five kinds of prey was the same as that for selection. Male and female fruit flies equally benefited the spiders. The fruit flies yielded the most and large beetle larvae the least number of statistically superior benefits. Small beetle larvae and milkweed bugs were intermediate and about equal. There was no evidence that a mixed (i.e., two) prey diet is better than a single prey diet. It is hypothesized that selective predation by P. vancouveri involves prey sampling, memory of prey attributes, and selection of prey that possess attributes that are associated with high fitness.

LC50 and LT50 values for two multicapsid nuclear polyhedrosis viruses isolated from the alfalfa looper, Autographa californica (Speyer), and a mint looper, Rachiplusia ou (Guenée), were determined against black cutworm, Agrotis ipsilon (Hufnagel), neonate larvae, 1-day-old larvae reared at 15 °C before testing, and 1-day-old larvae reared at 27 °C before testing. The results showed that black cutworm larvae have low to moderate susceptibility to these viruses. As the larvae developed, their susceptibility to the viruses rapidly declined. Initial growth of larvae surviving sublethal dosages of these viruses was reduced, but pupal weights of these larvae were not significantly different from untreated controls.

Leptocera (Thoracochaeta Duda), a subgenus of sphaerocerid flies associated with marine supralittoral habitats, is revised for the Nearctic Region. Keys are provided for separation of the nine Nearctic species. L. (T.) teskeyi, L. (T.) flaminuta, L. (T.) calminuta, and L. (T.) bajaminuta are described as new and L. (T.) zosterae is recorded from the Nearctic for the first time. The larvae of three species (zosterae, seticosta, and brachystoma) are described.

Yellowjackets (Vespidae: Vespula and Dolichovespula spp.) are painfully familar to most people. Many of these wasps are scavengers and are readily attracted to foodstuffs or food wastes. They also frequently nest in and around human habitations. These insects are generally considered of significant medical importance because of the allergic reaction in some people following a sting. Yellowjacket abatement programs have been conducted in many parts of the United States, usually associated with high wasp densities in orchards or recreation areas (McDonald et al. 1976).

The accumulation of monoterpenes during the defensive response by grand fir was quantified over a 28-day period. Monoterpene content increased exponentially with time and varied greatly among trees. Following analysis, sampled trees were observed for 4 years. Those trees which showed an extensive accumulation of monoterpenes in response to artificial inoculation with fungi transmitted by the fir engraver were less likely to be killed during this period than trees which exhibited low levels of secondary monoterpene accumulation. The extent of the defensive response was influenced by host age, disease, crown class, and artificial stress. Following inoculation with fungi transmitted by the fir engraver, the proportions of limonene, myrcene, and Δ-3-carene, present in the monoterpene fraction increased. In previously reported laboratory bioassays, each of these compounds has demonstrated higher toxic or repellent properties, or both, than have the other monoterpenes present in grand fir. Mechanical injury resulted in less pronounced reactions than did fungal inoculation. Necrotic lesion formation is accompanied by an increased concentration of short-chain hydrocarbons, followed by a decline to normal levels. Necrotic lesion formation and monoterpene synthesis represent at least two independent activities during the wound response.

An onion maggot, Hylemya antiqua (Meigen) (Diptera: Anthomyiidae) strain, having low level (≤ × 5) resistance to organophosphorus insecticides, was selected with parathion to determine if higher resistance levels to the selection agent and other insecticides used for onion maggot control would result. Parathion resistance levels increased to ×10.1 and ×23.8 after 4 and 14 generations of selection, respectively; without further selection, resistance levels declined by ca. 1/2 in 6–7 generations. Parathion resistance was ×24.4 after 20 generations of selection and resistance levels to ethion, diazinon, fonofos, and carbofuran were 2 to 3 times higher than those measured initially. The pattern of resistance development in field strains of onion maggot collected in 1975 and 1980 was similar to that observed in the laboratory selection program, but resistance levels were lower, probably because of lower selection pressure and the variety of chemicals used under practical conditions. After 14 generations of parathion selection, resistance levels were ×23.8 and ×10.1 to parathion and carbofuran, respectively. After 12 additional generations of carbofuran selection, carbofuran resistance increased to ×31.2, while the level of parathion resistance remained the same.

Tests of intertrap variability in catches of moths of the clover cutworm, Scotogramma trifolii (Rottenberg), were conducted by placing two traps baited with an artifical sex attractant at 1 mi (1.6 km) intervals to form a grid covering 25 mi2 (64 km2) near Domain, Manitoba. The 50 traps (2/location) placed near the intersects of the grid were baited with a blend of Z-11-hexadecen-1-yl acetate and Z-11-hexadecen-1-ol. This blend was 98.6% species-specific for S. trifolii. Moth catches varied between traps and flights, but the ranking of the traps by catch was consistent during any given flight period. Up to 35 traps would be required within an area of 64 km2 (1 trap/1.8 km2) to give a population estimate within 20% of the true mean. Temperature influenced both the initiation of the flights and the number of moths caught at any given time, but there were no correlations between flights and precipitation or wind. Crop type influenced catches of S. trifolii only when moth populations were large. The catch of second generation moths averaged 9.8× the catch of first generation moths. The consistency of this relationship indicates that the annual differences in population density are controlled by variations in winter survival. The latter was linked to the induction of diapause which is governed by daylength during the larval development of the second generation.