Laboratory tests, at constant temperatures, were conducted to evaluate quantitatively the influence of temperature on development of the Oriental fruit moth, Grapholitha molesta (Busck). The results showed that at the highest temperature (30°C) some larvae had four instars and some had five, indicating a mixed population. Fifth instar larvae developed only at the highest temperature (30°C) where larval development was also most rapid. It can, therefore, be assumed that the Oriental fruit moth has four distinct larval instars when reared in the laboratory at 15°–24 °C.

Two new species of Epiclerus Haliday from North America and the Greater Antilles are described and illustrated, these being the first records of the family Tetracampidae native to the New World.

Newly-hatched larvae from a selected (S) “non-diapausing” gypsy moth strain and larvae from field-collected wild (W) eggs were reared in field cages in Connecticut, U.S.A. beginning May 1976 to determine developmental rates and interbreeding potential. Reciprocal and inter se matings between S and W moths were monitored to determine if hatch occurred during the fall and if S and reciprocal F1 hybrid (SW, WS) eggs could successfully overwinter and hatch at an appropriate time the following spring. Hatch of S eggs did occur in the fall. Survival of SW, WS, and some S eggs over the Connecticut winter demonstrated that this non-diapause colony is not suitable for a genetic control program in which the non-diapause trait is expected to act as a conditional lethal.

A simple population model is used to test the hypothesis that Douglas-fir tussock moth population cycles are caused by time-delays in the responses of density-dependent (negative feedback) processes. The limited data that are available do not seriously conflict with this hypothesis.

Collections of Amitus (Hymenoptera: Proctotrupoidea, Platygastridae) from the Western Hemisphere are referred to the following species: from Canada and the United States, A. aleurodinis Haldeman, A. granulosus n. sp., and A. gibbosus n. sp.; from Mexico and South America, A. spiniferus (Brethes), A. pigeanus n. sp., A. hesperidum Silvestri, and A. fuscipennis n. sp.

A lateral plate-like process on the male fourth antennal segment is regarded as a phenocline, characteristic of species or species groups.

Three species of Twinnia, including hirticornis n. sp., and five species of Gymnopais, including dichopticoides n. sp., holopticoides n. sp., and fimbriatus n. sp., are described, keyed, and illustrated. The ancestral simuliid is portrayed as possessing cephalic fans, because several related nematocerous families, viz., the Ptychopteridae, Dixidae, and Culicidae, also have similar and presumably homologous structures in the larval stage which are used in the same fashion to ingest food particles suspended in water The peculiar Twinnia–Gymnopais larval type, which lacks cephalic fans, is considered to have arisen simply by a neotenic retention of the fanless condition found in the first instar of Prosimulium. Phylogenetically, Twinnia and Gymnopais are therefore considered to have been derived from a Prosimulium-like ancestor. Twinnia is intermediate phylogenetically between Prosimulium and Gymnopais, and the latter is believed to be the most recently derived, possibly as a response to the development of arctic–alpine conditions in Beringia during the Tertiary.

Snow depth is the most important environmental factor in the survival of overwintering Rheumaptera hastata (L.) pupae in interior Alaska. Pupae spend the winter in the leaf litter where litter temperatures are directly related to snow depth at given air temperatures. Winter survival is also dependent on the cessation of pupal development (diapause) and the development of cold-hardiness which is induced by certain physiological processes such as supercooling and changes in glycerol and carbohydrate levels. Glycerol content and supercooling are dependent on changes in carbohydrate levels which in turn are directly related to changes in the rate of pupal development prior to diapause.

Several authors (Charmillot and Baggiolini 1975; Proverbs et al. 1975; Roelofs et al. 1976; MacLellan 1976) have stated that mass-trapping male codling moths with sex pheromones did not provide economic control of this pest. MacLellan (1976), however, reported suppression of codling moth populations in unsprayed orchards 2-3 ha in size and Madsen et al. (1976) obtained similar results in orchards in which sprays were not applied specifically for codling moth control. In 1975 and 1976 similar studies were undertaken in three 0.5–0.75 ha plots (A, B, C) of mature apple trees at Vineland (Hagley 1970). Plots A and B had not received insecticide sprays from 1969 to 1974 and had relatively high codling moth infestation levels (Table I). Plot C had been on a pest management program since 1971.

Female budworm flight activity was monitored automatically at seven constant temperatures ranging from 10° to 25°C. Flight activity was negligible below 17.5°C, but considerable oviposition occurred as low as 15°C. It is therefore possible that during cool weather the number of insects dispersing is reduced, with the result that a larger proportion of the eggs are laid in the stand of origin.

The populations of Spilonota ocellana (D.&S.) on two cultivars in an insecticide free orchard showed nearly identical trends over a 12-year period. Egg populations reached maximum numbers when the orchard was 9 years old and the ensuing larvae infested 33% of the clusters the following year. A marked decline in all stages occurred when the orchard was 11 to 12 years old and this was immediately followed by a second peak of less intensity on both cultivars. The only difference in mortality of the population on the two cultivars was found in neonate larvae. The average survival of egg to pupa for the 12-year period was near 7%.

Colonies of P. fuscatus that were initiated by various numbers of foundresses were studied to gather basic life table information. This information was used to estimate the selective advantage of foundress association according to a kin selection model, a parental manipulation model, two individual selection models, and a combined kin and individual selection model. Life table data were obtained for colonies located in exposed nest sites and for colonies located in nest sites provided with protection from vertebrate predators. Relative productivity of colonies produced by different size foundress associations and under different levels of predation pressure were determined. Multiple foundress colonies were found to be more productive and have an increased ability to re-establish after an episode of predation when compared with single foundress colonies. When predation levels on the colonies were high, multiple foundress colonies were more productive per colony and per foundress. When predation levels on the colonies were low, multiple foundress colonies were more productive per colony but less productive per foundress. At high levels of predation, when the queens and joiners were all assumed to have equivalent potential productivities, the kin selection model, the parental manipulation model, and the combined kin and individual selection model all predicted a selective advantage for joiners in foundress associations. At low levels of predation, when the wasps are assumed to have equivalent productivities, only the parental manipulation model predicted a selective advantage for joiners in foundress associations. When the assumption of equivalent potential is relaxed and when the wasps are assumed to be capable of detecting and acting upon individual differences in productivity, then all of the models could account for the existence of foundress associations. However, under this last set of assumptions the individual selection models require that the joiners have very low potential productivities.

The efficacy of mixtures of chlordimeform with Bacillus thuringiensis and(or) Autographa californica nuclear polyhedrosis virus and Pieris rapae granulosis virus against Trichoplusia ni and Pieris rapae on the late cabbage was assessed in field plots over four growing seasons. Mixtures of 0.07 kg of chlordimeform/ha (1/8 of the recommended dosage) with low concentrations of the microbial insecticides were as effective or more effective than the materials used alone at full rates. The advantages of such mixtures in pest management are discussed.

A local population of P. apachus in California was studied to determine population structure and colony survival during the first 3 months of colony development. Only 24.2% of the colonies survived to the end of July. Bird predation on colonies (60.6%) and loss of foundresses (12.1%) were the main causes of colony failure. Bird attacks occurred approximately 2 weeks prior to the emergence of workers and the scrub jay, Aphelocoma coerulescens, was identified as one of the avain predators. All colonies that survived this initial period persisted until observations were discontinued in late July.

The spectrum of contact toxicity and activity in soil of four pyrethroid insecticides was assessed in the laboratory. Pyrethroids tested were: FMC 33297 (3-phenoxybenzyl (±)-3-(2, 2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate); Shell WL 41706 (alpha-cyano-3 phenoxybenzyl 2,2,3,3-tetramethylcyclopropanecarboxylate); Shell WL 43467 (alpha-cyano-3-phenoxybenzyl 2-(2,2-dichlorovinyl)-3,3-dimethylcyclopropane-1-carboxylate); and Shell WL 43775 (alpha-cyano-3-phenoxybenzyl-2-(4-chlorophenyl)-3-methyl-1-butyrate). Chlorpyrifos and carbofuran, two broad spectrum contact and soil insecticides were included for comparative purposes. Spectrum of contact toxicity was determined using 24–48 h nymphs of the common field cricket, Acheta pennsylvanicus (Burmeister), 24–48 h onion maggot adults, Hylemya antiqua (Meigen), 3rd instar dark sided cutworms, Euxoa messoria (Harris), northern corn rootworm adults, Diabrotica longicornis (Say), and honeybees, Apis mellifera L. Crickets were used to assess insecticidal activity in soil relative to soil moisture, type, and temperature. The pyrethroids were effective contact insecticides comparable in toxicity and spectrum of activity to chlorpyrifos and carbofuran. They were particularly toxic to the darksided cutworm. They were less effective in mineral soil than chlorpyrifos. WL 43467 showed activity in mineral soil close to that of carbofuran, while the other pyrethroids were less active. Activity in soil was influenced by soil moisture and type. In contrast to the standard insecticides the pyrethroids generally showed a negative temperature coefficient of toxicity in soil.

Within-tree colonization by Dendroctonus frontalis infesting loblolly pine, Pinus taeda L., was investigated. Two components of the colonization process were studied: the establishment of attacking adults (ATK) and the ensuing construction of egg galleries (GL). Data on the two variables were taken from standing trees beginning at the time of initial attack and continuing for 14 consecutive days.

The spatial and temporal sequence of ATK was described for 1.5 m intervals along the infested bole for the duration of the process. A three parameter nonlinear function was used to describe the data. The pattern of attack was also described as an average process for the entire tree using the same model. A frequency histogram encompassing the range in variation for peak ATK from 134 trees was prepared to provide starting values for simulation purposes.

The spatial and temporal sequence of GL construction was described using essentially the same approach as employed for ATK. The modeling process was complicated by loss or obscuring of GL from the radiograph by omission errors and foraging by Monochamus spp. and other associates. GL construction was also described as an average function for the entire tree and the rate of GL construction was defined. A frequency histogram of peak GL was prepared from data on 54 trees for use in selecting starting values for simulation purposes.

Numerical relationships between ATK and GL were defined by combining the data on ATK and cumulative expected GL.

Adults of the sweetclover weevil, Sitona cylindricollis Fähr., injure seedling, vegetative, and yearling sweet clover, Melilotus officinalis (L.) Lam. In field cage tests an infestation of 1 weevil: 7 seedlings at the cotyledon stage destroyed less than 5%, and an infestation of 1 weevil: 1 seedling destroyed 100% of the seedlings. Significant reduction of seedlings was caused by infestations of I weevil: 3 or 5 seedlings depending upon growing conditions. An infestation of 4.5 to 9 weevils per emergent second-year plant caused a significant reduction, and an infestation of 18 weevils per plant caused almost total destruction of second-year forage yield. In the Canadian mid-west, weevil populations seldom exceed these minimum threshold values, therefore the weevil should not be considered a deterrent to either stand establishment or to stand retention in the second year. Defoliation of vegetative clover by weevils at the beginning of and mid-way through the critical period, which extends from 15 August to 20 September, caused a 50% loss of second-year forage yield. Because of cultural practices associated with sweet clover production in western Canada this may be the most severe type of injury wrought by the weevil.

Because laboratory and field cage experiments had shown that partially sterile (25 krad dose) male codling moths were sexually more competitive than sterile (40 krad) ones, a study was made in a British Columbia orchard in 1970 to determine whether release of 25 krad moths of mixed sexes would suppress this pest more effectively than release of 40 krad moths. Approximately 75,000 moths/ha were released from 24 April to 25 September for each dose level. In the 25 krad moth release plot, the percentage of apple fruits damaged by this pest at harvest was reduced from 0.21 in 1969 to 0.08 in 1970, whereas in the 40 krad plot damage was reduced from 0.04 in 1969 to 0.02 in 1970.

Release of 25 krad moths was also compared with insecticide sprays for codling moth suppression in two small areas at Cawston and Olalla, B.C. At Cawston, the percentage of apples damaged at harvest was reduced from 1.0 in 1969, after three sprays of phosalone, to 0.1 in 1970 after release of irradiated insects. In contrast, per cent damage in a nearby apple orchard, sprayed twice with azinphos-methyl in 1969 and 1970, increased from 2.0 in 1969 to 8.1 in 1970. At Olalla, per cent damage was about the same (0.5) in 1969, after three phosalone sprays, as in 1970 (0.6) after release of irradiated insects. In a neighboring apple orchard, sprayed twice with phosalone in 1969 and 1970, per cent damage was about the same (1.0–1.2) each year.

Grylloblatta campodeiformis Walker were collected from a site in the Alberta Rocky Mountains at an altitude of 1300 m. The gut contents in the autumn consist almost entirely of arthropods. Dominant among these was a tipulid fly, equally typical of the cold, montane habitat as Grylloblatta itself. In the laboratory, G. campodeiformis adults eat only live or recently killed animal prey, and neither adults nor larvae grow without animal food. Prey is detected by the antennae and then seized by the mandibles. Five types of sensilla, all of which are probably involved in prey identification, are described from the antennae and palpi.

Newly hatched larvae of Chironomus decorus, Endochironomus nigricans, and Chironomus staegeri mostly from a single shallow eutrophic pond near St. Catharines, Ont., were reared to the adult stage at 15°C and 20°C and 16 and 8 h daily photoperiods. Normal development to EM50 took 26 days at 20°C and 37 days at 15°C in C. decorus; 35 and 48 days in E. nigricans; and 68 days at 20°C in C. staegeri. The 8 h daily photoperiod inhibited emergence, by preventing pupation of final instar larvae, in E. nigricans and C. staegeri at both temperatures, and in C. decorus at 15°C. Nevertheless, a few individuals emerged even under these conditions; such individuals may be important in insuring field populations against environmental variation.

Food supply was normally adjusted to permit only partial emergence even in non-inhibiting regimes. After initial emergence was complete, more food was added to some replicates. In suitable regimes, remaining larvae then completed metamorphosis. Larvae undergoing delayed metamorphosis (for whatever reason) suffered mortality at low food levels; this suggests that food was required for maintenance even by individuals in which metamorphosis was inhibited by photoperiod/temperature combinations alone.

After a further period, when any food-induced emergence had been completed, transfers to higher temperatures or longer photoperiods were made. Transfer after initial inhibition to regimes that normally permitted emergence resulted in emergence; and in E. nigricans transfer at 8 h photoperiod from 15 °C to 20 °C also resulted in emergence, suggesting that the cues for induction and termination of dormancy are not the same, since 8 h photoperiod normally induces dormancy at both temperatures. Emergence after such transfers was more highly synchronized than in the initial period, but protandry was generally retained.

The overwintering adult of Ooencyrtus kuwanai (How.) is susceptible to freezing. Male adults from New Jersey have a mean supercooling point of −9.6 ± 0.37°C, significantly higher than those from Maine (−12.3 ± 1.08°). Neither group had its cold hardiness increased by exposure to sublethal temperatures. Female adults from New Jersey had a mean supercooling point of −10.8 ± 0.69° when tested after rearing at 22°C, again significantly higher than that of similarly treated female adults from Maine (−15.4 ± 0.90°). Exposure of New Jersey females to sublethal temperatures decreased their supercooling point significantly, to −14.5 ± 1.59°. Maine female adults were not tested after that treatment. No adults survived continuous exposure to 0°C for 30 days. Hence this parasite is apparently incapable of surviving in the current range of the gypsy moth in Canada.