Liriomyza sonchi Hendel was screened for its host specificity as a potential biological control agent against sow-thistles (Sonchus spp.). Recent literature indicated that L. sonchi is recorded frequently from Sonchus spp., but also from Arnoseris minima Schweigger and Koerte and Reichardia arabicum Hochstetter and Steudel. A total of 78 plant species were tested, including 37 species in the Cichorieae (Compositae). In no-choice tests, feeding punctures were observed on species in the closely related genera Aetheorrhiza, Crepis, Lactuca, and Taraxacum, and such distantly related species as Helichrysum bracteatum Andrews var. monstrosum Hortorum (Inuleae tribe, Compositae) and Pisum sativum L. (Leguminosae). From 0.04 to 0.67 adults per female were produced on Aetheorrhiza bulbosa (L.), Crepis dioscordis L., C. rubra L., Leontodon hispidus L., and Taraxacum officinale Weber as compared with about 23 per female on its host, Sonchus arvensis L. No species in these genera other than Sonchus are reported as hosts in the field in Europe and they are therefore considered to be cage-induced hosts. Because of its economic importance, 10 cultivars of lettuce, Lactuca sativa L., were exposed to a total of 837 females in no-choice tests. One puparium and one adult (0.006 per female) were produced. In one replicated choice test with 150 females, no mines were produced on lettuce. It is concluded that the field host range of L. sonchi is restricted to Sonchus spp.

The distribution of spruce beetle attacks and length of associated egg galleries were investigated on 21 spruce stumps over a 4-year period in central British Columbia. Attack density formed a distinct vertical gradient which peaked near the duff line at about one-third stump height above the mineral soil. The proportion of attacks on the stumps that were located below the duff was linearly related to the ratio of stump height below duff and total stump height above mineral soil. Attack density was significantly higher below the duff than above. A three-parameter exponential function gave satisfactory fit to the attack density gradient on normalized stump height. A discrete-step theoretical model was also developed based on assumptions regarding beetle behavior during landing and imitation of the egg gallery and the physical characteristics of the host. This model gave an excellent fit to the attack density gradient as an average process over all stumps. Average egg gallery length was a curvilinear function of attack density with maximum average egg gallery length occurring at about 0.33 attacks per 100 cm2.

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.

The seasonal damage to female reproductive structures (buds, flowers, and cones) of black spruce, Picea mariana (Mill.) B.S.P., was assessed during 1983 and 1984. Nineteen insects (five Orders) and the red squirrel, Tamiasciurus hudsonicus (Erxleben), were found feeding on these reproductive structures. Collectively, these organisms damaged 88.9 and 53.5% of the cones in 1983 and 1984, respectively. In the 2 years, Lepidoptera damaged 61.8% of the cones in 1983 and 44.4% of the cones in 1984. The spruce budworm, Choristoneura fumiferana (Clem.), and the spruce coneworm, Dioryctria reniculelloides Mut. and Mun., were the most important pests. Cones damaged by Lepidoptera could be classed into three categories: (a) severe, yielding no seeds; (b) moderate, yielding 22.3 seeds per cone; and (c) light, yielding 37.5 seeds per cone. Undamaged cones yielded on average 39.9 seeds per cone. Red squirrels removed 18.8% of the cones in 1983 and none in 1984. The spruce cone axis midge, Dasineura rachiphaga Tripp, and the spruce cone maggot, Lasiomma anthracinum (Czerny), caused minor damage in both years. Feeding by spruce cone axis midge did not reduce cone growth significantly or the number of viable seeds per cone, but feeding by the spruce cone maggot did. During both years new damage by insects to the female reproductive structures of the experimental trees was not observed after mid-July. In 1983 damage by red squirrels occurred from early to late September. In 1984 damage to cones on trees treated with dimethoate was 15.6% compared with 53.5% for untreated trees, without an increase in the number of aborted cones.

Larvae of Lacinipolia patalis (Grote) (Lepidoptera: Noctuidae) were discovered in Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) cones collected from the Louisiana-Pacific Corporation's Little River Seed Orchard near Trinidad Head in Humboldt County, CA (elevation 91 m) during the fall of 1985. Previous surveys have not reported this noctuid from Douglas-fir cones (Keen 1958; Tietz 1972; Furniss and Carolin 1977; Hedlin et al. 1980; Ruth 1980; Schowalter et al. 1985). Its usual hosts are blackberry and loganberry (Rubus spp.) and roses (Rosa spp.); it normally feeds on foliage and, to some extent, dead fruit bases and dead leaves (Crumb 1956). The shift from angiosperm leaves and fruit to gymnosperm cones is somewhat surprising. Blackberries, however, grow around the perimeter of the seed orchard and along the rows between trees, and so provide an abundance of the usual host for L. patalis nearby.

The Lasionycta skraelingia (H.-S.) species complex, formerly considered to include only one species, is shown to consist of six species. Three species (Lasionycta buraetica Kononenko, from the Sayan Mountains, USSR; L. corax Kononenko from the Upper Kolyma River area, USSR; and L. taigata Lafontaine from northern Canada) are described as new. The name L. alpicola, proposed by Hampson as an aberration of L. skraelingia, is validated as a species. The taxon Lasionycta phaea (Hampson), currently treated as a subspecies of L. impingens (Walker), is shown to be a distinct species in the L. skraelingia complex; a lectotype is designated for Anarta phaea Hampson. Adults and genitalia are illustrated for the six species; a key to species and distribution maps are also included. Lasionycta membrosa (Morrison, 1875) is placed in synonymy with L. subdita (Möschler, 1860).

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.

Two populations of Pissodes strobi (Peck), one from Sitka spruce, Picea sitchensis (Bong.) Carr, and the other from Engelmann spruce, Picea engelmannii Parry ex Engelm., were successfully induced to oviposit on the non-host lodgepole pine, Pinus contorta Dougl. var latifolia. The number of egg punctures excavated on the non-host was smaller than that on either Sitka or Engelmann spruce. Survival from egg to adult was similar on the non-host and the host trees. The two weevil populations differed in the degree to which lodgepole pine met the nutritional requirements for weevil development, as measured by weight of weevils and developmental time from egg to adult. In choice-feeding experiments, weevils reared in lodgepole pine rejected this species and chose Sitka spruce, suggesting that feeding preference in P. strobi is genetically fixed and therefore cannot be changed by rearing the insects on the non-host tree. The importance of these findings is discussed in relation to the idea of weevil control through the development of weevil-resistant varieties.

Annual catches of male spruce budworm (Choristoneura fumiferana [Clem.]) in sex pheromone traps over a 21-year period in northwestern Ontario were well correlated with larval population densities in each subsequent year (r2 = 81%). On the basis of the criterion of 3 successive years of increasing catches or a threshold of 50 moths per trap, warning of extensive defoliation could have been given 6 years in advance. In 18 plots in northwestern Ontario and 35 plots distributed throughout the province, coefficients of determination (r2) between catch and population density in the same generation ranged from 40 to 74% in 1982 and 1983, but fell below 23% in 1984 when population densities in many plots were high. Coefficients of determination between catch and population densities in the following generation (eggs or larvae) ranged from 41 to 62%. On the basis of several years of cooperative research, sex pheromone traps are now in operational use in eastern North America for monitoring spruce budworm populations.

A mathematical model was constructed to simulate the effect of intraspecific larval competition on the survival of Agromyza frontella (Rondani). It was shown that the probabilities of cannibalism and starvation can be expressed as functions of larval density and food availability (leaflet surface area), and that expected pupal weights can be determined from the amount of food available to the third-instar larva. Predictions were compared with data from laboratory experiments and field samples with excellent results.

The control of the Colorado potato beetle, Leptinotarsa decemlineata (Say), by formulations of Bacillus thuringiensis (Berliner) (B.t.) and other microbial agents and chemical insecticides was assessed in field plots of potatoes and tomatoes over a 5-year period. Applications of formulations of thuringiensin, the beta exotoxin of B.t., and of B.t. var. son diego (B.t.sd.) to potatoes reduced numbers of larvae of the potato beetle compared with the nontreated check and resulted in yields significantly greater than from the check plots and, in most cases, similar to yields from plots treated with carbofuran. Treatment of tomatoes with B.t.sd. reduced populations of larvae of the Colorado potato beetle compared with the nontreated check and increased yield of nondamaged fruit from plots. An initial application of carbofuran to potatoes or permethrin to tomatoes followed by applications of thuringiensin or B.t.sd. protected potatoes or tomatoes as well as did the chemical insecticide used alone in a treatment program. Applications of preparations of B.t. var. kurstaki or spores of the fungus Beauveria bassiana (Balsamo) Vuillemin or the microsporidium Vairimorpha necatrix (Kramer) did not reduce populations of the beetle.

In an attempt to control the larch casebearer, Coleophora laricella (Hübner), in western North America with biological agents, insect parasites from Europe and Japan were introduced (Denton 1972, 1979; Ryan et al. 1987). The braconid Agathis pumila (Ratz.) has become widely established and apparently has been responsible for markedly reduced casebearer densities (Ryan 1983, 1986; Ryan et al. 1987). Parasitization by it in many research plots reached 80-95% (unpublished data), then declined following reductions in the casebearer populations in a typically delayed density-dependent manner. I present here a partial explanation for why casebearer densities declined so drastically, to levels even lower than could perhaps be explained by parasitization at such high levels.

The larvae of all known species of Acroceridae are internal parasites of spiders (Araneae) and recently (Sferra 1986), first-instar larvae have been described from mites (Acari). The eggs usually are laid in close proximity to their hosts, and the first-instar larvae (planidia) wait for, or actively seek, a host. Once a host is found, the larvae burrow through the spider's integument and attach to the book lungs where they remain in diapause for several months. The consecutive larval instars occur rapidly, during which time the larva consumes most of the liquid contents of the host. The larvae emerge posteriorly from the host, attach to the spider silk for pupation, and adults emerge in 7–10 days. Acrocerid biology was most recently reviewed by Schlinger (1969, 1981).

Pterostichus melanarius Ill. was the predominant ground beetle recovered in pitfall traps in three blocks of apple trees at Jordan Station, Ont. In one block, C, the number of mature fifth-instar larvae of Cydia pomonella (L.) seeking overwintering sites was related significantly (r2 = 0.5476, P < 0.05) to the number of P. melanarius caught, but was not related significantly (r2 = 0.1181, P > 0.10) to the proportion of beetles that were serologically positive. The proportion of larvae pupating also was not related significantly (r2 = 0.2014, P > 0.10) to the number of P. melanarius. The total number of all predators caught was related significantly (r2 = 0.4490, P < 0.05) to the number of larvae present, but the proportion of larvae that pupated was not related significantly (r2 = 0.3606, P > 0.05) to the total number of predators.

In block A, in 1983–1985, the number of mature larvae of C. pomonella seeking overwintering sites was not related significantly (r2 = 0.3763, 0.3619, and 0.5042, P > 0.05, respectively) to the number of P. melanarius taken in pitfall traps. In both blocks A and B, the number of serologically positive beetles was not related significantly (r2 = 0.3824 and 0.7921, P > 0.10, respectively) to the number of larvae seeking overwintering sites.

Amara aenea DeG., Anisodactylus sanctaecrucis F., Bembidion quadrimaculatum oppositum Say, Clivinia impressifrons LeC., Diplochaeila impressicolis (Dej.), Harpalus aeneus F., and Pterostichus chalcites Say also gave positive serological reactions to the antiserum against C. pomonella.

The occurrence of other species of Lepidoptera did not affect significantly the results obtained for C. pomonella.

Ecological data, distribution records, comments, and diagnostic features are given for eight European species of Longitarsus Latreille introduced into North America: L. ferrugineus (Foudras); L. succineus (Foudras); L. luridus (Scopoli); L. jacobaeae (Waterhouse); L. ganglbaueri Heikertinger; L. pratensis (Panzer); L. pellucidus (Foudras); and L. rubiginosus (Foudras). The last two species are reported for the first time in North America.

The influence of various aspects of Malaise trap design on efficiency in collecting various groups of Hymenoptera was compared using commercially available traps. The influence of fine and coarse mesh sizes and the importance of the incorporation of pan traps into the design were evaluated in two sampling periods in an old dune community at Pinery Provincial Park in southern Ontario. Numbers of individuals collected in Malaise trap heads and pan traps were presented for each paired comparison of mesh size (fine and coarse) and location (top and bottom of a hill) for various families of Hymenoptera. A graphical analysis of the normalized catch data for more inclusive groupings, viz. Symphyta, Aculeata, Ichneumonoidea, and microhymenoptera, was presented. The major results of these comparisons were as follows: (1) pan traps were an important component of efficient Malaise traps, especially for Aculeata and microhymenoptera; (2) coarse mesh was more effective in collecting Aculeata; (3) coarse and fine mesh were both effective in collecting Ichneumonoidea; and (4) fine mesh was more effective in collecting microhymenoptera. There was an interaction effect between the type of trap used and groups collected and it was not possible to maximize simultaneously the collection of all groups of Hymenoptera. The use of various mesh types and a trap design that incorporates pan traps was recommended.

Pinus pumila Regel growing at Takanegahara Plateau of Mt. Taisetsu, Hokkaido, Japan, were damaged by larvae of Cephalcia variegata Takeuchi and Gilpinia daisetusana Takeuchi. The feeding behavior and life history of C. variegata are reported.

In the eastern deciduous forests of North America, oaks (Quercus spp.) that have been weakened by stress are often attacked and killed by the twolined chestnut borer, Agrilus bilineatus (Weber) (Dunn et al. 1986a). This borer attacks stressed and dying trees but does not attack healthy or dead trees (Haack and Benjamin 1982; Dunn et al. 1986a, 1987).