The blueberry maggot, Rhagoletis mendax Curran, is the most important insect pest of lowbush blueberries. Concern for maggot does not generally result from direct crop losses, but from its presence in harvested fruit which can affect marketability.

Fortunately, the blueberry maggot is not a problem in all lowbush blueberry areas (Wood 1979), but where it does occur, producers are advised to apply one or two sprays annually. General recommendations often result in the unnecessary use of insecticides, especially in years when populations are at low levels because of natural control and management practices. Such misuse could be prevented if monitoring techniques were developed that provide information on seasonal adult prevalence.

Prosimulium fuscum and P. mixtum larvae and adults may be readily separated on the basis of unique complements of electromorphs at the 6-phosphogluconate dehydrogenase locus. The species are closely related and share common electromorphs at 10 other polymorphic and monomorphic loci. Numerical analysis of 24 morphological characters from larvae shows cephalic fan ray number and the length of the postgenal bridge plus hypostomium can be used to identify most individuals to species. A possible environmental component in determination of morphotype may prevent correct identification of all larvae. Lack of utility of other characters currently used in keys to separate the species is discussed.

Two blocks (one .36, other .48 ha) of filbert (hazelnut), Corylus avellana L., trees were left unsprayed for 10 years and the pest status of different species determined by periodic field examination and damage counts. The omission of all pesticides resulted in excessive build-up of the filbertworm, Melissopus latiferreanus (Wals.) (Lepidoptera: Olethreutidae) populations resulting in an average of over 20% nut damage. Filbert leafroller, Archips rosanus (L.) (Lepidoptera: Tortricidae), and filbert aphid, Myzocallis coryli (Goeze) (Hemiptera: Aphididae), populations declined and no apparent economic damage was caused by these two pests. No damage was observed from other recorded arthropod pests.

An economic analysis of standard filbert pest control programs in the Willamette Valley of Oregon indicated that during the study years, the total insecticide spray expenditures in commercial orchards ranged from 6.5% to 18.3% of the yearly returns in U.S. dollars/ha. Damage in unsprayed study orchards during this 10-year period suggests that the sprays applied for the control of aphid and leafroller yielded no return, while the sprays applied for control of the filbertworm returned an average of $3.80 for every dollar spent.

Parathion-resistant (R) (× 24) onion maggot (OM), Delia antiqua (Mėigen) (Diptera: Anthomyiidae), adults showed 15-, 9.3-, and 7.7-fold levels of cross-resistance to direct contact applications of chlorpyrifos, naled and chlorfenvinphos, respectively, when compared at the LD50 with an insecticide-susceptible OM strain. R OM also showed 3.4-, 2.9-, 1.6-, and 1.3-fold levels of resistance to deltamethrin, permethrin, cypermethrin, and fenvalerate, respectively. The low-level resistance to the pyrethroids was probably conferred from DDT, to which the R OM strain had a 4.7-fold resistance level. Nevertheless, deltamethrin, cypermethrin, fenvalerate, and permethrin were 137, 58, 28, and 17 ×, respectively, more toxic to the R OM strain than was parathion.

The predominant predator of the pear psylla, Psylla pyricola Foerster, in a pear orchard on the Niagara Peninsula, Ontario was the anthocorid, Anthocoris nemoralis (F.). Applications of permethrin (62.5 g a.i./ha) reduced numbers of the predator when applied at petal fall. Azinphosmethyl (336.4 g a.i./ha) applied at petal and at 1st cover did not affect A. nemoralis. Both insecticides reduced the numbers of the predatory mite, Balaustium putmani Smiley. Species of Hemiptera other than A. nemoralis, especially Miridae and Reduviidae, were reduced by permethrin applied at petal fall and by azinphosmethyl applied at 1st cover.

Field studies were conducted in which adult white pine weevils, Pissodes strobi (Peck), were confined on the leaders of six different conifer species and various parameters of weevil attack were recorded. Eastern white pine, Pinus strobus, the preferred native host, was the most susceptible to attack and the most suitable for brood production. All white pine leaders on which 3 or 6 male–female pairs of weevils were confined were killed, and mean numbers of emerging brood adults per leader were 26.0 and 37.3, respectively. Some leaders of the other species of pine and of spruce, Picea spp., were also killed, but brood production from them was very low. White spruce, P. glauca, leaders proved to be the least suitable for production of brood because no adult progeny emerged, even from leaders that had been killed.

Male and female adults of Neomideopsis siuslawensis n. gen., n. sp. are described from Oregon, U.S.A. The genus Neomideopsis is proposed and diagnosed based primarily upon the strikingly autapomorphic presence of 17–23 genital acetabula on each acetabular plate flanking the gonopore. Possible relationships between N. siuslawensis and other Mideopsidae, especially species currently placed in Mideopsis (Nudomideopsis), are discussed.

Recent collections (1980–1982) of winter stoneflies in southern Manitoba have resulted in the addition of five previously unrecorded species: Capnia coloradensis Claassen, C. confusa Claassen, Paracapnia angulata Hanson, Skwala parallela (Frison), and Utacapnia trava (Nebeker and Gaufin) to the nine previously recorded species. Eight of the 14 species now known from Manitoba occur in the small spring-fed streams on the east escarpment of the Duck Mountain Provincial Park. The probable zoogeographical origins and present distribution of winter stoneflies in Manitoba are explained in light of various post-glacial drainage patterns. Adults of U. trava were observed, often copulating, on the underside of the ice. They were also observed crawling away from streams with no ice cover to a distance of 50 m.

Damage caused by Empoasca fabae (Harris) and Philaenus spumarius (L.), caged on second and third alfalfa harvests, was additive. Numbers of E. fabae were linearly correlated negatively with plant height, leaf area, and percentage protein, and positively with percentage chlorosis. Perceptible stunting and yellowing occurred with mean infestations per stem of 0.09 E. fabae and 0.6 P. spumarius nymphs. P. spumarius adults reduced plant height only at infestations of 0.3/stem, while 0.6 nymph/stem also reduced dry weight. E. fabae reduced protein at 0.11/stem and dry weight and leaf area at higher populations of 0.17/stem. None of these parameters was affected on subsequent regrowths. Lygus lineolaris (P. de B.) could not be maintained on pre-bloom alfalfa and was not considered a pest. Adelphocoris lineolatus (Goeze) reduced protein at levels of 0.01 bug/stem and dry weight at 0.06 bug/stem but results were confounded by high mortality. Field populations of all these species were reduced by the second cutting but redeveloped on the regrowth. Although applications of dimethoate (200 g AI/ha) and dimethoate (200 g AI/ha) plus endosulphan (280 g AI/ha) were effective in reducing populations of E. fabae, Acyrthosiphon pisum (Harris), A. lineolatus, and Hypera postica (Gyllenhal), insecticides were cost-effective on only one field. This field had 1.9 E. fabae/sweep and a 3% loss in protein resulted. Plant height, density, dry weight, protein content, and overwintering survival were not significantly affected at harvest in other fields. With the exception of E. fabae, the sum of the maximum field populations, each expressed as a fraction of its threshold, did not reach 50% of an economic threshold.

The 6 LC50 for nymphs of Hexagenia rigida exposed to permethrin-contaminated water without sediment was estimated to lie between 0.58 and 2.06 μg/L. No nymphs survived a 6 h exposure to 7.63 μg/L. Laboratory simulated application of 7.3 g/ha permethrin to H. rigida nymphs in culture resulted in a final mortality of 88.0 ± 15.2% after a 1-day exposure, and 100.0% after a 7 day exposure; initial permethrin concentrations in water were estimated to be 7.63 μg/L and maximum mean concentrations in sediment, measured 1 and 7 days after application, were estimated to be approximately 50 μg/kg dry weight. Exposure of nymphs to sediment contaminated 8 days previously resulted in 100.0% mortality. An application of 0.6 g/ha resulted in final mortality of up to 45.0 ± 4.1%. Lethal effects occurred in some cases between 1 and 4 and possibly up to 10 weeks after application.

Leaf samples were taken from crowns of sugar maple trees at selected vertical and horizontal positions and at each cardinal point. No significant differences in numbers of mines, cuts, or cases of Paraclemensia acerifoliella (Fitch) were observed among the cardinal points of the crown. Most of the mines were found on leaves located near the base of the crown and close to the tree bole. Significantly more mines/leaf were found on samples 0.6 and 1.2 m from the bole than at 2.4 m and outward to the edge of the foliage. The highest number of cases/leaf was found 1.2 m from the bole. One and two months after the leaf-mining stage both case-bearing larvae and leaf damage were more prevalent from the bole outward to a distance of 3 m.

The northern corn rootworm, Diabrotica longicornis (Say), was first reported by Guibord (1976) in QuCbec corn fields, and has since been studied intensively as a potential pest of corn. Detailed field investigations of the bionomics were initiated at h4acdonald Campus in 1979, and laboratory research such as physiology and toxicology required the development of techniques for mass rearing of the insects.

Required sample size was determined for early instar (2nd to 4th instar) larvae of spruce budworm, Choristoneura fumiferana (Clem.). Larval counts on mid-crown 45 cm branch tips and whole branches of balsam fir, Abies balsamea (L.) Mill., were described in terms of the negative binomial distribution. The values of common k for the branch tip and whole branch sample units were 1.550 and 1.636, respectively. The required sample size at densities greater than or equal to one appears feasible. It is recommended that the 45 cm branch tip be used to estimate population density of early instar larvae in Newfoundland.

The age at which Pseudaletia unipuncta females initiated calling varied with temperatures experienced during pupal and adult stages. Entrainment was induced by temperatures during pupal development if similar to or lower than temperatures during adult life. However, adult temperatures were of major importance if lower than those experienced during pupal development. These observations were generally supported by data from field experiments repeated at different periods of the summer. The possibility that entrainment occurs at a specific period of development is proposed to explain certain field observations.

Changes in mean onset time of calling and the time spent calling also varied, although generally not in the same manner as reported for other species. Differences in the life cycles, particularly the site of pupation, are proposed to explain these discrepancies.

Chrysops univittatus Macquart females were more abundant in late July and early August in southwestern Quebec. Dry-ice baited canopy trap collections consisted of 55% (n = 177) of the nulliparous and 77% (n = 91) of the parous females. Incidence of nectar feeding, as determined by cold anthrone test, was 73% (n = 244) and 96% (n = 268) of the females contained sperm; no difference was found between parous and nulliparous females. This species is anautogenous, and only one gonotrophic cycle was recorded following ovary dissection. Number of ovarioles was correlated with body size (as determined by wing length) by linear regression analysis.

The parasite and predator component of within-tree southern pine beetle, Dendroctonus frontalis Zimmermann, mortality was investigated by mechanically excluding insect parasites and predators from the bark surface of naturally infested shortleaf, Pinus echinata Mill., and loblolly, P. taeda L., pines. Mortality caused by insect parasites and predators was determined by comparisons of five treatments that differed only in the duration of natural enemy exclusion. These natural enemies were responsible for 28.04% and 23.85% of the within-tree beetle mortality in 1978 in Arkansas and in 1979 in Georgia, respectively. Natural enemy species that arrived on the tree during the first week following mass attack by beetles caused the greatest amount of mortality.

Predator density was greater than parasite density at both locations. The majority of the predator complex arrived during the first week following mass attack by beetles, while the parasite complex arrived throughout the entire period of beetle brood development.

A linear response was found between the number of southern pine beetle prey and the number of prey destroyed per predator. A mean (± S.E.) of 4.79 ± 0.64 southern pine beetle immatures were destroyed by each individual predator.

Methamidophos proved more suitable than methomyl for incorporation in an integrated pest management program for celery. Methomyl applications resulted in increased leaf mining and greater emergence of Liriomyza species leafminers. Methomyl use also increased adult parasite mortality, and significantly reduced the rate of parasitism by approximately 50% as compared to methamidophos or control treatments. Species composition of parasites was influenced by pesticide treatments; the Diglyphus species, Chrysocharis species and Halticoptera circulus (Walk.) demonstrated tolerance, but Chrysonotomyia punctiventris (Crawford) was intolerant.

Numerous spruce budworm, Choristoneura fumiferana (Clem.), moths were observed and trapped in western Newfoundland between 8 and 17 July 1982. At that time about 91% of the native Newfoundland budworm population was in the 5th and 6th instars and less than 1% had pupated. Spruce budworm moths probably emigrated with the aid of suitable weather from New Brunswick to Newfoundland.

Vol. 114, 1982

p. 1102, Table I, column 1, 2nd last entry, forZ7-12:OH + E9-14:Ac read Z7-12:OH + Z9-14:Ac

One complete generation of Simulium vittatum (Zett.) was reared in each of two trials using a Cornell automated rearing system. Insects reared from eggs oviposited in the laboratory by field-collected females constituted the parental generation. The feeding regimen used to rear the parental generations resulted in a shorter mean developmental time, larger adults, and a higher potential fecundity of females than obtained in previous rearings of S. vittatum in this system. Adults of both parental rearings mated and produced offspring with net reproductive rates of 0.048 and 0.027 for the first and second trials respectively. None of the eggs oviposited by F1 adults embryonated, due to the small number of F1 females and the low insemination rates.