Two bioassay methods using leaf discs and Petri dishes as the treated medium were compared. Resistance levels were approximately 11-fold with the leaf disc method and 7-fold using the Petri dish assay. Comparisons of the two methods on six wild populations indicated that the Petri dish assay was more sensitive in identifying low frequencies of resistance. Advantages of the Petri dish assay over the previously used leaf disc method for rapid, field-type surveys are discussed.

Surveys of populations from the Simcoe and Niagara areas, using the Petri dish assay, indicated resistance to dicofol in 11 of 22 samples. Resistance was generally correlated with sites where dicofol had been used at least once a year for 2–3 consecutive years. The data indicate a resurgence of dicofol resistance since 1984 when resistance was detected at 4% of the surveyed sites.

Mutants of Drosophila melanogaster (Meigen) with altered resistance to the insecticide malathion were isolated and tested for their avoidance response to the insecticide. A correlation between sensitivity to the insecticide and increased avoidance was detected. Approximate chromosome map locations were determined for the loci of the mutations.

Requirements for diapause development of larvae of Choristoneura fumiferana have been generally believed to be met by temperatures of 2°C or below for a period ranging from 14 to 20 weeks (see review by Sanders 1991), whereas those favourable for post-diapause development were shown to be above 11°C (Régnière 1990). However, we noticed that a large number of larvae completed diapause after 10 weeks at 18°C without any cold storage. The following experiment was carried out to confirm this result.

Blethisa inexspectata is described as new from one male specimen from Alaska; it is the sister species of B. julii LeConte. The phylogeny and biogeography of Blethisa Bonelli is discussed, and a key to all known species of Blethisa is given. Blethisa kaszabi Jedlička 1967 is placed in synonymy with B. tuberculata Motschulsky 1846.

Application of 5 Ibs. toxicant Ileptachlor or aldrin per acre placed in a 4- to 5-inch hand about 1½ inches below the surface of the soil in a ridged seeding drill have controlled infestations of the cabbage root maggot, Hylemya brassicae (Bouche) in cabbage and rutabagas for eight consecutive years on one farm in Prince Edward Island without detectable indications of resktance. The insecticide is so placed in the soil as to be most concentrated against the young root maggot larvae and least concentrated against the following predators and parasites: Coenosia tigrina (Fall.) and Scatophaga stercoraria. (L.), which attack and destroy H. brassicae flies in flight, on the soil surface, or on plant foliage; various species of Carabid beetles which destroy H. brassicae eggs at or near the soil surface, Trybliographa rapae (L.), the larvae of which parasitize and destroy H. brassicae larvae in the plant roots; and Aleochara bilineata (Gyll.), with adults destroying H. brassicae eggs or young larvae near the soil surface, and larvae in the plant roots, and the larvae parasitising H. brassicae puparia and destroying the pupae. Records of field observations, supplemented with data obtained on green-house determinations of the potential reproduction of both predators and host, indicate that any one of these predators could theoretically eliminate the pest population from an area in two to three generations. They do not eliminate or even give apparent economic control of the pest because a) the aerial attackers do not find and destroy adults of the pest before many eggs are deposited in the soil; b) many eggs are hidden in the soil by wind and rain and thus protected from discovery by predators; and c) larval and puparial parasites attack after the pest has injured the crop.

This paper offers a taxonomic treatment of the American species belonging to the genus properly known as Phratora but designated as Phyllodecta Kby. by recent authors. Phyllodecta was described by Kirby in 1837 (p. 216); the month of publication is given as October by Sherborn (1929, p. 4931), and, according to Westwood (1837). Kirby's volume was presented on November 6 to the monthly meeting of the Entomological Society of London. Phratora has been attributed to Redtenbacher, because he was the first to publish the name with a description of generic characters, and has been dated 1845 (p. 116) or 1849 (p. 554). Phratora Redt., lacking priority, has been considered a synonym of Phyllodecta Kby. However, in 1837 both Chevrolat (p. 405 or 429) and Faldermann (p. 363) used Phratora in ways that would validate the name; Chevrolat's usage, and possibly that of Faldermann, antedates Kirby's description of Phyllodecta. Chevrolat listed previously described species Phratora, and his usage, as shown by Barber and Bridwell (1940, p. 4), was published between March 1 and July 5, 1837. Faldermann, without comment on the genus, described a new species in Phratora, but the exact date of his publication is unknown. The species considered by all these authors are congeneric. A consideration of genotypes is impractical at this time, but such is not required to show that the genus should be known as Phratora and that Phyllodecta is a synonym.

The potato aphid, Macrosiphum euphorbiae (Thomas), infests oilseed flax, Linum usitatissimum L., when the crop is flowering and developing seeds. Field studies in cages, open plots, and commercial fields showed that the aphid can cause yield losses of 20% or more, but reduces the weight of individual seeds only slightly and has no effect on oil quality. A single application of a foliar insecticide at full bloom or the green boll stage will control the potato aphid until harvest. The yield loss of flax is 0.021 t/ha per aphid per plant for crops sampled at full bloom and 0.008 t/ha per aphid per plant for crops sampled at the green boll stage. The economic threshold for the potato aphid in flax is three aphids per plant at full bloom and eight aphids per plant at the green boll stage, based on crop prices and control costs from 1990 to 1992. Aphids should be controlled as soon as the economic threshold is exceeded. If control is not warranted at full bloom, aphid densities should be assessed again at the green boll stage. The effective use of growth-stage-specific sampling and economic thresholds will maximize the benefits of insecticide use for producers and minimize unnecessary or ineffectively timed applications.

Results of an experiment reported previously (Rivard, 1958a) showed the influence of various humidities on mortality and rate of development of the immature stages of Tyrophagus castellanii (Hirst)reared on mould cultures at a constant temperature. Results of an experiment on the influence of humidity on the longevity and fecundity of the adult mites are reported in the present paper. Information gathered from both studies is used to calculate the innate capacity of the species for increase at different humidities.

An artificial key is presented to separate the second to fourth instar mosquito larvae of eastern United States and Canada, west to and including Texas and Manitoba. A second, natural key, separates the genera and many of the subgenera. A list of the 134 included species and subspecies with their ranges within this region is given, with indicated corrections since Carpenter and LaCasse (1955) and the Stone et al. (1959) catalog. Larvae of two species are unknown.

Tuberculatus Mordwilko as here understood consists of the following 14 species: californicus (Baker), capitatus (Essig and Kuwana), columbiae Richards, kiowanicus (Hottes), maureri (Swain), orientalis new species, pallidus (Davidson), pasaniae (Davidson), querceus (Kaltenbach), quercicolus (Matsumura), querciformosanus (Takahashi), stigmatus (Matsumura), tuberculatus new species, and yokoyamai (Takahashi). Tuberculatus previously included querceus and columbiae. Each species is redescribed and illustrated, and a key and a host index are provided.

A sequential sampling program was designed for Coccinella septempunctata L. adults in wheat fields, based on a rapid visual counting method. This program takes into account the spatial heterogeneity of coccinellids and the efficiency of the counting method. The relationship between the mean and variance of the numbers sampled was described by Taylor’s power law.

A rod-shaped noninclusion virus infects the European red mite, Panonychus ulmi (Koch), in Ontario. Infection and death can occur in any postovarial stage. Most infected mites contain, in the midgut, more or less spheroidal inclusions with a radiating crystalline structure. Infected mites deposit inoculum on the leaves, probably in excreta or oral secretions at feeding sites, which is picked up orally by uninfected mites while feeding. The inoculum on the leaves is very unstable, seldom remaining infective for more than a week and being almost immediately inactivated after exposure to water. Suspensions of infected mites, triturated in water or various solutions, were inefficient inocula.Introduction of virus into orchard populations of P. ulmi induced epizootics that rapidly reduced the population density. Natural epizootics were found only in dense populations.

Since 1953, plantation omers in southern Ontario have suffered serious losses from a group of tip-infesting insects of the family Tortricidae. These insects live primarily on the herbaceous ground-cover plants but may ascend trees under about 3 feet in height and feed on the new shoots during May and June, killing or injuring the leaders and causing serious growth deformities. Five species are involved, of which Tortrix alleniana Fernald and T. pallorana Robinson are common, and Archips rosaceana Harris, Sparganothis sulfureana Clemens, and S. unifasciana lemens occur only as scattered individuals among larger populations of the two common species. This paper records the most salient points in the life history and general ecology of T. alleniana and T. pallorana, with notes on the other three species.

The coffee white stem borer, Xylotrechus quadripes (Chevrolat) is a major pest of coffee, Coffea arabica (L.) (Rubiaceae), in South Africa, India, Thailand, and China (Duffy 1968; Schoeman 1990; Visitpanich 1994; Montavon 1997). Females lay eggs singly or in batches, generally under bark crevices of the stem. Neonatal larvae feed beneath the bark and, during development, bore deeply inside the stem. Stems are colonized by up to 60 larvae. Extensive damage by larvae causes mortality of coffee plants or reduction of fruit production (Duffy 1968; GK veeresh). Because larvae inside the stems of coffee plants are difficult to control, management tactics are aimed at preventing infestation, either by interfering with oviposition of females or by killing neonates before they bore into the stem. Our study tested insect and host plant derived stimuli that may affect the selection of oviposition sites by female X. quadripes.

The foraging and tending behavior of the ant Dolichoderus taschenbergi (Mayr) was studied for 5 years in southwestern Pennsylvania. The ant used well-defined foraging trails and avidly collected honeydew from tuliptree scales, pine aphids, and less abundant sources. The ants increased the survival rate of tuliptree scales from 8.2 to 46.8%, probably by interfering with the activities of parasites and predators.

Two newly identified geographic isolates of a nucleopolyhedrovirus (LdMNPV-H and LdMNPV-J) were evaluated against Disparvirus (LdMNPV-D), a baculovirus insecticide registered in Canada for the control of gypsy moth (Lymantria dispar (L.) (Lepidoptera: Lymantriidae)). Profiles of HindIII and EcoRI restriction enzyme digests of viral DNA from the three viral isolates are presented. Viral isolates were bioassayed using an inoculated diet plug method to determine the dose- and time-responses of second-instar larvae of both the European and Asian strains of gypsy moth. LdMNPV-D was found to be the most virulent isolate when tested against the European strain of gypsy moth, yielding an LD50 and an LD95 (estimates of the doses required to kill 50% and 95% of the test larvae, respectively) of 95 and 774 occlusion bodies (OBs), respectively. LdMNPV-H was the most virulent isolate when tested against the Asian strain, yielding an LD50 and an LD95 of 648 and 8540 OBs, respectively. Time-response data indicate that the three isolates differ little with respect to their speed of kill (ST50; estimate of the length of time required to kill 50% of the test insects) of either larval strain. These results indicate that both new isolates (LdMNPV-H and LdMNPV-J) should be investigated further for control of the Asian strain of the gypsy moth but not pursued for control of the European strain.

Three species of Telenomus Haliday are egg parasitoids of the hemlock looper, Lambdina fiscellaria (Guenée), in Canada. Telenomus coloradensis Crawford and Telenomus droozi Muesebeck are redescribed and Telenomus flavotibiaesp.nov. is described and illustrated from material collected in Quebec. Telenomus coloradensis was found to be the predominant egg parasite, followed by T. droozi. Telenomus flavotibiae was found to be an uncommon parasite of hemlock looper eggs. All three species are recorded from Newfoundland to British Columbia. Keys to species of Telenomus associated with the hemlock looper, including two closely related species previously confused in the literature, are also given.

Extracellular hook electrode recordings were made of activity in the ventral nerve cord of the larvae of Orthosoma brunneum (Forster) during application of 30% CO2 to the head region. The work involved bilateral amputation of the tip segments of antennae, maxillary palps, and labial palps so that each specimen bore only one intact pair of the three sensory organs. Larvae with only intact antennae exhibited no response to CO2 in the ventral nerve cord; larvae with only maxillary palps did respond; larvae with only labial palps did respond, but less noticeably. Maxillary and labial palps are sites of CO2 reception in O. brunneum.

Reproductive processes in female Pissodes strobi (Peck) fed with a 5% ground bark artificial diet following summer emergence were studied. Females exposed to different temperature and photoperiod regimes were dissected every other week and their reproductive organs were observed to evaluate the maturation time according to the treatments. After 12 weeks, half the females were transferred onto lateral branch sections of white pine and the other half onto artificial diet supplemented with 10% ground bark of white pine, and their realized fecundity was determined. During the first 12 weeks, ovary development was detected but very few mature oocytes were found. No significant differences were observed for the maturation times between the different abiotic conditions used, but significant differences were observed in female egg-laying response on natural and artificial diets. Females that completed their sexual maturation at 24 °C and 16L: 8D laid over a 3-week period 14.4 ± 8.8 (mean ± SE) and 2.6 ± 2.6 eggs per female on white pine sections and artificial diet, respectively. Oviposition behaviour was compared with results from an earlier experiment conducted with spring-emerging white pine weevils on natural and artificial substrates. The egg-laying responses on white pine seedlings and on an artificial diet with a concentration of 15% ground white pine bark were 0.892 ± 0.124 and 0.171 ± 0.394 eggs per female per day, respectively.

Intraguild predation, a common interaction among arthropods (Polis et al. 1989), has been investigated recently in aphidophages (Rosenheim et al. 1993; Lucas et al. 1998). Sessile stages of coccinellids, gall midges, and lacewings (eggs, moulting individuals, and pupae) were shown to be highly vulnerable to intraguild predators (Lucas et al. 1998). Several defensive mechanisms have already been described for eggs of aphidophages, including chemical protection (Eisner et al. 1996), structural protection (Canard and Duelli 1984), and behavioural avoidance through the selection by females of protected oviposition sites (E. Lucas, and J. Brodeur, unpublished data).