Experiments conducted in a plantation of oil palms, Elaeis guineensis (Jacquin), infested with bagworms, Metisa plana (Walker), tested the hypotheses that crowding enhances the incidence of larval ballooning and negatively affects the size attained by pupae. Proportions of ballooning larvae increased with increasing densities of larvae per palm. The lengths of bags (and pupal cases) decreased with increasing numbers of bagworms per leaf. Ballooning of larvae from crowded palms is likely adaptive because individuals attaining large size at pupation have proportionately greatest survival, mating success, and fecundity.

The distribution of the yew big bud mite, Cecidophyopsis psilaspis (Nalepa), a pest causing severe damage to Pacific yew, Taxus brevifolia Nutt., was determined within British Columbia. From 1992 to 1994, vegetative and reproductive buds on branch samples collected from 38 interior and 43 coastal populations of Pacific yew were examined for the occurrence of the mite. Mite damage was characterized by marked swelling and browning of both vegetative and reproductive buds. Interior Pacific yew populations were found to be mite free, whereas coastal yew populations were mite infested, except at three high-elevation (>700 m) coastal locations which were apparently mite free. At three other sites, individual trees without symptoms of mite attack did harbour low-density, nondamaging mite populations. The hypothesis that this mite is indigenous is less supported than the hypothesis that it was introduced to British Columbia on English yew, Taxus baccata L., and is limited to its present distribution by climatic and mountain barriers.

Danausplexippus L. (Lepidoptera: Nymphalidae) is a cosmopolitan species, distributed in America wherever milkweed grows (Amett 1985). Its migratory phenomenon spans Canada, the United States, and Mexico and it has been considered endangered since the 1980s (IUCN 1983).

Ackery and Van-Wright (1984) compiled 45 species of food plants used by immature stages and 70 species of plants attractive to adults of the Monarch butterfly. Malcolm and Brower (1986) listed 28 host plant species recorded in nature. Lynch and Martin (1993) added six Asclepias species and observed larvae on three species of milkweed vine, Sarcostemma crispum and S. cynancroides in Texas, and Cynanchum laeve in Louisiana.

Timema bartmani sp.nov. is described from San Bernardino County, California. Both sexes are known. Males show relationship with Timema podura Strohecker. Females closely resemble Timema tahoe Vickery. Timema bartmani may be the sexual ancestor of the parthenogenetic T. tahoe.

The forest tent caterpillar, Malacosoma disstria Hiibner, is widely distributed throughout North America and is subject to a variety of naturally occurring infectious diseases, including a nuclear polyhedrosis virus (NPV). NPVs have been isolated from several Malacosoma species in North America and Europe, including M. disstria, M. neustria, M. americanum, M. fragile, M. alpicola, M. californicum, M. pluviale, and M. constrictum (Stairs 1964). The viruses isolated from all North American species of Malacosoma may be cross transmitted from one species to another (Clark 1958). Distinctive isolates of NPV have been characterized from populations of M. disstria in Alberta (Keddie and Erlandson 1995) and Ontario (Ebling and Kaupp 1995).

Two opposing hypotheses are tested regarding the choice of oviposition sites by female Aedes togoi (Theobold) mosquitoes: (i) conspecific avoidance—females discriminate against sites harboring conspecifics to reduce intraspecific competition for their offspring and (ii) conspecific attraction—females prefer sites with conspecifics because their presence indicates suitable conditions for larvae. Under laboratory conditions, A. togoi females laid many more eggs on rearing water (LRW) containing conspecific larvae, their waste, bacteria, and food supplements than on rearing water alone (RM). In another experiment, females showed an oviposition preference for LRW sites that were devoid of A. togoi eggs compared with those harboring 50 (0.3 eggs/mL) conspecific eggs. Further, it was discovered that females laid their eggs at several sites rather than at a single suitable site. Possible reasons for such choices are discussed.

Listronotus montanus (Dietz) is a little known species, distributed in central North America. O'Brien and Wibmer (1982) record its occurrence from Indiana west to Nevada and north to the Prairie Provinces. In Montana, it occurs widely in grasslands east of the Continental Divide (Montana Entomological Collection, unpublished), but is also recorded from Saunders Co. in western Montana (Russell 1968). Nothing has been reported on the biology of this species, but it has been observed on grasses in the Cypress Hills of Alberta (CWOB unpublished). We report the occurrence of this species as a potential pest of small grains.

A second species of the dry wood termite genus Marginitermes Krishna is described from Baja California del Sur, Mexico, and a redescription of the genus is provided. Soldier head capsules, mandibles, antennae, labra, postmenta, and pronota are illustrated for Marginitermes cactiphagus Myles sp.nov. and Marginitermes hubbardi (Banks). Both species occur in dead skeletons of columnar cacti and other wood species. Both species differ from related drywood termites in the structure of the proventricular armature, suggestive of unique adaptation for intestinal manipulation of cactus wood fibres. Marginitermes is shown to be related to a western continental subgroup of Incisitermes comprised of I. minor (Hagen), I. marginipennis (Latreille), and I. fruticavus Rust.

In 1994 and 1995 insects were collected from several sites in southern Manitoba, where purple loosestrife, Lythrum salicaria L., is dominant. Collection techniques included the use of trap plants, sweep netting, vacuum sampling, and hand collecting. Insects from 38 families were collected and grouped into four general feeding guilds: herbivores, predators, omnivores, and fungivores. Herbivores that directly fed on L. salicaria included Galerucella nymphaeae Linné (Coleoptera: Chrysomelidae), Myzus lythri (Schrank) (Homoptera: Aphididae), Poecilocapsus lineatus (Fabricius) (Hemiptera: Miridae), Kleidocerys resedae (Panzer) (Hemiptera: Lygaeidae), Ametastegia glabrata (Fallén) (Hymenoptera: Tenthredinidae), Orgyia leucostigma (Smith) (Lepidoptera: Lymantriidae), Lophocampa maculata (Harris) (Lepidoptera: Lymantriidae), Spilosoma virginica (Fabricius) (Lepidoptera: Arctiidae), Simyra henrici (Grote) (Lepidoptera: Noctuidae), Dichomeris ligulella (Hübner) (Lepidoptera: Gelechiidae), Melanchrapicta (Harris) (Lepidoptera: Noctuidae), Hyles galli (Rottenburg) (Lepidoptera: Sphingidae), and Biston betularia cognataria (Gn) (Lepidoptera: Geometridae). These herbivores cannot severely limit the density of purple loosestrife in southern Manitoba and any interactions with the introduced agents should be minimal. The predatory stink bug, Apoecilus bracteatus Fitch (Hemiptera: Pentatomidae), was identified as a potentially important predator of the introduced biological control agents, Galerucella pusilla Duftschmidt and Galerucella calmariensis (L.) (Coleoptera: Chrysomelidae).

Ptomaphagus inyoensis is described from Poleta Cave, Inyo County, California. Its reduced, but present, eyes and reduced flight wings suggest that it is a deep soil species. The spermatheca shape and other characters suggest that it is in a group with Ptomaphagus fisus Horn, a species widespread in animal nests and burrows in the southwest, Ptomaphagus cocytus Peck, a cave-restricted species from the Grand Canyon of Arizona, and Ptomaphagus manzano Peck, a montane litter species from New Mexico. A comparative morphological analysis of the group is presented.

The fir coneworm, Dioryctria abietivorella (Grote), is a major insect pest in seed orchards across Canada and the adjoining eastern and western United States. Larvae feed principally on cones, but they can also feed on needles and occasionally on the bark of young tree trunks (Hedlin et al. 1980; Ruth 1980; Martineau 1985). The potential for a population of D. abietivorella to build up in seed orchards may be greater than in natural stands (Hedlin et al. 1980; Ruth et al. 1982). The use of entomopathogen in the management of fir coneworm could be an adequate measure to reduce the impact of this insect. Moreover, Bacillus thuringiensis ssp. kurstaki has a specific effect on Lepidoptera (Aronson et al. 1986; Gill et al. 1992). The purpose of our study was to determine the activity of the HD-1 strain of B. thuringiensis ssp. kurstaki (serotype H-3a:3b) to larvae D. abietivorella. Bioassays were conducted with first-, third-, and fifth-instar larvae of fir coneworm to determine whether or not the insect's vulnerability to B. thuringiensis varies with larval age.

The nun moth (NM), Lymantria monacha (L.), is one of the most important defoliators of coniferous forests in Eurasia (Bejer 1988). It was reportedly established near Brooklyn, New York (Holland 1941), but according to Ferguson (1978) “either the report was wrong or monacha did not persist, as there is no evidence of its presence now.” The potential entry of NM to North America poses a severe threat to the vitality, biodiversity, and stability of coniferous forests. The economic and environmental costs of existing exotics and the potential entry of new ones, such as NM, justify proactive management and heightened international quarantine efforts.

Recent identification of an attractive and species-specific pheromone blend in NM from the Czech Republic (Grant et al. 1996; Gries et al. 1996) provides the opportunity to develop pheromone-based NM detection surveys in North America. However, as has been demonstrated for other moth species (Klun et al. 1975; Thompson et al. 1991; Tóth et al. 1992), pheromone blends of geographically wide ranging species, such as NM, may be regionally specific. Therefore, attraction of Asian NM males to the European NM pheromone blend needed to be tested.

The lengths of the scale bars were left off three of the figures. On page 727 for Figs. 18–21 the caption should read: Scale bar = 0.5 mm; on page 728 for 13gs. 22–25 the caption should read: Scale bar = 0.2 mm; and on page 730 for Figs.31–35 the caption should read: Scale bar = 0.5 mm.

Bagworms (Lepidoptera: Psychidae) have an unusual life history (Borror et al. 1989). Following eclosion, apterous females stay within their pupal case and the protective bag they constructed as larvae. Females attract winged males by expelling pheromone-impregnated scales outside of their pupal case into the lower extremity of the bag. Sexual segregation of pupation sites has been found in three bagworms, Thyridopteryx ephemeraeformis (Haworth) (Gross andFritz 1982), Oiketicus kirbyi (Guilding) (Rhainds et al. 1995a, 1995b), and Metisa plarza (Mlker) (Rhainds, unpublished). In all three bagworms, proportionately more female than male larvae pupate in the upper strata of trees. Pupation of females in upper sites is adaptive because it may enhance any to all of the following: pheromone dissemination (Gross and Fritz 1982), mate attraction (Rhainds et al. 1995a, 1995b), progeny development (Rhainds, unpublished), and dispersal of neonatal larvae (Cox and Potter 1988). We report habitat segregation between male and female pupae of the bagworm Clania cramerii (Mstwood) (Thangavelu and Ravindranath 1985).

Cassida azurea Fab. (Coleoptera: Chrysomelidae) was studied as an agent to control the weed bladder campion, Silene vulgaris (Moench) Garcke (Caryophyllaceae). To supplement previously published data on the beetle’s host range, additional no-choice experiments were conducted. First-stage larvae were offered seven plant species related to bladder campion. Only one adult male developed on Dianthus caryophyllus L. cv. China Doll and one female on Lychnis × haageana Lem. This female did not produce eggs when it continued to feed on L. × haageana. In tests with adults, oogenesis occurred only if fed with bladder campion, and one laid one egg while feeding on Gypsophila pacifica Kom. First-stage larvae did not develop to adults on three native North American Silene spp., but two adults developed on three other native species. Based on results from these experiments and reports in the literature, it was concluded that C. azurea has a very narrow host range and permission for field releases was granted in 1989. Releases were made in Manitoba, Saskatchewan, and Alberta from 1989 to 1993. Cassida azurea survived from 3 to 6 years and was considered established at 8 of the 18 release sites in the three provinces but has not yet increased to densities sufficient to reduce bladder campion populations.

The development of adult and nymphal populations of Lygus lineolaris (Palisot de Beauvois), L. elisus Van Duzee, and L. borealis (Kelton) was studied in relation to seeding date and stage of plant development in four seedings of canola (cv. Westar) in field plots at Glenlea, Manitoba, in 1988 and 1989. Lygus lineolaris was the dominant species in all seedings and in both years. Colonizing adults (first-generation adults) of the three Lygus spp. first invaded the plots at about the same time from the late rosette to the early flowering stages of plant development, and Lygus adult numbers reached maxima during flowering in all seedings. The stage of plant development, and not seeding date, was important in attracting colonizing adults of Lygus to canola. Second-generation nymphs first appeared at the flowering stage of canola. All nymphal instars reached maxima and median abundances during the late flowering and pod development stages in all seedings. Second-generation adults were present from early to late pod development stages. Median abundances of second-generation adults of L. lineolaris, L. elisus, and L. borealis usually were reached at the same plant growth stage in each seeding.

Three new mymarid egg parasitoids of the carrot weevil, Listronotus oregonensis (LeConte) (Coleoptera: Curculionidae), are described: Anaphes cotei Huber from Nova Scotia; Anaphes listronoti Huber from Quebec; and Anaphes victus Huber from Quebec, Michigan, and Texas. A key to the species is given. Anaphes sorditatus (Girault), with which at least one of the new species was previously confused, is redescribed. Although listronoti and sorditatus cannot presently be distinguished morphologically, they are biologically distinct and have different hosts. Crosses between male sordidatus and female victus yielded female offspring in 27% of the tests but none in the reciprocal crosses. The corresponding control crosses resulted in 90 and 30% female offspring. Mating did not occur in attempts to cross sordidatus with listronoti. On three occasions an unidentified species of Anagrus was reared from field-collected carrot weevil eggs. This represents the first report of an Anagrus species from Curculionidae.

The legends of the tables were inverted. Consequently, the legend at the top of Table 1 on p. 594 should be above Table 2 on p. 602. Likewise, the legend above Table 2 should be above Table 1.

Yellow water pan traps and yellow sticky traps were used to collect Delia spp. flies in plots of canola, var. Tobin, for an entire growing season in the Peace River region of Alberta. At one or more times during the growing season, pan traps and sticky traps captured Delia radicum (L.), Delia floralis (Fallen), Delia planipalpis (Stein), or Delia platura (Meigen). Numbers of males and females caught varied dramatically between the two trap styles, both within and between the various species. Prior to the onset of flowering, cumulative captures of each of the four Delia spp. in pan traps were all significantly lower than on sticky traps for females and males. From the onset of flowering until trapping ended on 17 August, cumulative captures of D. radicum, D. floralis, and D. planipalpis females were similar in pan traps and sticky traps. Sticky traps, however, remained significantly better than pan traps for trapping all Delia spp. males, as well as D. platura females. Pan traps were more suitable than sticky traps for collecting intact specimens for positive identifications. Results indicate that a combination of sticky traps and pan traps should be used over an entire growing season when conducting initial surveys for Delia species in crops such as canola. In routine monitoring programs for Delia spp., sticky traps would be more efficacious early in the growing season and more practical than pan traps. The level of expertise required to accurately identify the Delia spp. complex in canola would be higher for sticky traps than for pan traps.