A model of predation by Podisus maculiventris (Say) on Mexican bean beetle, Epilachna varivestis Mulsant, larvae in soybeans is presented. The attack equation described the number of prey attacked as a function of the number of prey, soybean leaf area, and the search behavior of the predator. The area searched by P. maculiventris was related to the amount of leaf area and the number of prey. Predictions of the number of Mexican bean beetles attacked per predator were compared with an independent field data set. The relevance of the predation model to studies of predation in other agricultural systems is discussed.

The seasonal activity and infestation potential of the cabbage maggot, Delia radicum (L.) (Diptera: Anthomyiidae), attacking rutabaga was studied at two Manitoba locations over 4 years based on captures of females in yellow water traps baited with alryl isothiocyanate. The activity peak for the overwintering generation occurred on 8 June ± 4.1 days (mean ± SD), with degree-day accumulations, base 5°C, of 159 ± 6.2 for soil at 5 cm and 387 ± 69.4 for air for both locations combined. The activity peak for the first generation occurred on 12 August ± 11.7 days with degree-day accumulations of 981 ± 229.3 and 1295 ± 175.7 for soil and air temperatures, respectively.

Correlations between numbers of females trapped per week and of eggs in soil samples from around rutabaga plants for individual seasons at the two locations generally were not significant. A regression of numbers of eggs on females trapped based on all data was significant but had a low coefficient of determination (r2 = 0.289). The water traps are adequate for monitoring seasonal activity of adult flies but the captures are unreliable as quantitative indicators of potential infestation.

The efficacies of cypermethrin, deltamethrin, permethrin, endosulfan, methoxychlor, carbofuran, chlorpyrifos, dimethoate, and malathion were evaluated against the wheat midge, Sitodiplosis mosellana (Géhin). Methods are described for evaluating damage and protection in individually collected wheat heads and whole plants. Weighted values from whole plants provided the best indication of kernel protection and yield response.

Whole plants contained three main types of wheat heads (primary heads, first tillers, and second tillers) which differed in their frequencies, kernel numbers, and developmental times. The latter indicated that the chronology of midge attack, status of midge infestations during spraying, and spray coverage also differed in the head types.

Insecticides provided different levels of kernel protection within and among the various head types. The majority of primary heads emerged before spraying and harbored midge eggs at spraying. In these wheat heads, chlorpyrifos, endosulfan, and malathion provided significantly better kernel protection (60–75%) than permethrin, deltamethrin, and cypermethrin (<7%). The results suggested that the more effective kernel protectants permeated the spikelet and controlled the eggs and/or newly hatched larvae. Kernel protection in the primary heads was closely related to insecticide volatility. Conditions were different in most first tillers and second tillers which emerged after spraying. In these wheat heads, poor spray coverage and short residual activity against adult midge appeared to limit kernel protection by all insecticides.

Field bioassays were used to assess the toxicities of four formulated insecticides to representative stream invertebrates. Toxicities (48-h LC50) after a 1-h application period ranged from 2.0 to 7.1 μg/L for permethrin, 82 to 284 μg/L for fenitrothion, 344 to 1276 μg/L for aminocarb, and 251 to 1504 μg/L for mexacarbate. Invertebrates drifted at concentrations of permethrin greater than 0.5 μg/L, and at concentrations of fenitrothion, aminocarb, and mexacarbate greater than 10 μg/L. An aerial application of 280 g AI/ha fenitrothion with no stream buffer was made to compare bioassay results with impact to aquatic invertebrates under operational spray programs. Concentrations of fenitrothion peaked 30 min after spray at 31.0 μg/L and declined to less than 1.0 μg/L within 14 h. Numbers of drifting invertebrates increased 20-fold 3 h after spray and declined to before-spray numbers within 24 h. Mortalities of caged invertebrates in the stream ranged from 0% for Pycnopsyche sp. to 16% for Simulium venustum (Say). The field bioassay accurately predicted the impacts of fenitrothion on stream invertebrates in this situation.

Stems of Canada thistle (Cirsium arvense (L.) Scop.), with galls of Urophora cardui (L.) at various stages of development, were brushed with a concentrated solution of dimefhoate to kill the gall-inducing larvae. Tissues of untreated and treated galls were compared to study the influence of larvae on each phase of gall growth and development. Galls treated in the initiation phase stopped growing. Galls treated in the growth phase grew slightly, primary nutritive tissue was replaced by a thick layer of proliferating callus, and lignified tissue appeared in its normal location. Galls treated in the maturation phase retained the arrangement of their secondary nutritive tissue but it degraded and callus did not develop in the larval chambers. We concluded that active larvae were necessary for normal gall growth and for the retention of primary nutritive cells, but larvae were not necessary for the formation of lignified tissues or for the retention of secondary nutritive cells.

Cicindela hirticollis Say 1817 is associated with shoreline and riverine sand deposits and is widely distributed in North America. Geographic variation in this species was analyzed by multivariate analysis of size, elytral markings, and color data obtained from some 4000 specimens from 75 sites throughout the species distribution. Eleven subspecies are recognized and discussed: C.h. hirticollis Say, gravida LeC., ponderosa Thorns., abrupta Csy., rhodensis Calder, corpuscula Rumpp, shelfordi, athabascensis, coloradula, couleensis, and siuslawensis Graves. Possible Pleistocene réfugia, and redistribution of the species following continental glaciation are discussed. Theoretical advantages of certain variants in particular climates or on certain substrates, are considered. Cicindela hirticollis has been eliminated or is endangered in many of its former habitats due to human activities.

Five new subspecies are described: C. h. shelfordi (type locality: Guthrie, OK) which inhabits the Great Plains region; C. h. athabascensis from the Lake Athabasca Sand Dunes of Saskatchewan and Alberta; C. h. coloradula from the Little Colorado River, AZ; C. h. couleensis (type locality: Vantage, WA) which is distributed in the Columbia–Snake river system of Washington, Oregon, and Idaho; and C. h. siuslawensis (type locality: Florence, OR) which inhabits the Pacific coast of Oregon and Washington.

North American species of the Oeneis polixenes (Fabricius, 1775) complex are reviewed. Two new subspecies, Oeneis polixenes luteus and Oeneis polixenes woodi, as well as one new species, Oeneis philipi, are described from northwestern North America. Oeneis polixenes peartiae (Edwards, 1897) is synonymized with Oeneis polixenes subhyalina (Curtis, 1835).

In a recently completed study involving pheromone trapping of the winter moth, Operophtera brumata (L.), and the Bruce spanworm, O. bruceata (Hulst), on Vancouver Island (Pivnick et al. 1988), I noticed that O. bruceata had wing colouration different from sympatric O. brumata. The west coast O. bruceata has a pale yellow-orange costal margin on the underside of the forewings and this is faint to absent in O. brumata (Fig. 1). It is also absent from O. bruceata in Saskatoon, which is interesting because some authors consider the west coast population of O. bruceata to be a separate species: the western winter moth, O. occidentalis (see Ferguson 1978; Pivnick et al. 1988). Descriptions of O. bruceata (Brown 1962) and O. brumata (Cuming 1961), and a taxonomic key to these two species (Eidt et al. 1966), do not mention any distinctive wing markings that could be used to separate the two species.

Richards (1972) described Aulacorthum pterinigrum from a holotype and eight paratypes on Pteris sp., Vancouver, B.C., 15 June 1967 (Fitz-Gerald), and two paratypes on Vaccinium sp., Terrace, B.C., 18 July 1960 (W.R. Richards). Chan has recently discovered that the holotype and paratype slides from “Pteris” should actually have been from Pieris sp., not Pteris sp. Pieris is a genus in the family Ericaceae, as also is the genus Vaccinium, mentioned above for two paratypes.