Individual variability in the flight potential of Ips sexdentatus Boern. was investigated using flight mill experiments. Non-flyer status and flight durations were studied in relation to day of emergence, sex, pronotum width, dried body weight (after lipid ether extraction), and lipid content estimate. Lipid content estimation was determined in beetles reared on the same trees and under identical conditions as the flight test insects.The four flight-tested cohorts showed that approximately one-third were non-flyers. The distribution of individual flight durations was described by a log-normal curve. Consequently, the dispersal variability within the population could be fitted to a linear model on a log-probit scale. The concept of FD50 (flight duration 50), defined as the flight duration of 50% of a sample population, was used to describe population flight potential.There was no significant correlation between the individual flight duration and the day of emergence, sex, body size or weight, or lipid content estimate. A significant positive correlation was recorded between the different classes of flyer (i.e. non-, short, long, and very long flyers) and the average lipid content estimate. It was hypothesized that (1) a minimum threshold fuel supply was necessary to initiate the dispersal flight and (2) fuel supply could result in dispersal tendencies representing a specific response to habitat constraints.

A new genus, Nitidotachinus, is described in the subfamily Tachyporinae (Staphylinidae) to include the species formerly placed in the Tachyporoides and Impunctatus groups of Tachinus Gravenhorst and Tachinus excellens Bernhauer. The new genus includes 10 species, all previously described, from North America, Japan, China, and Taiwan. All major diagnostic characters for the genus are compared with those of Tachinus and illustrated with scanning electron photomicrographs or line drawings. The following new combinations are created by transferring the species from Tachinus to the new genus Nitidotachinus: N. adachii (Watanabe and Shibata), N. agilis (Horn), N. excellens (Bernhauer), N. horni (Campbell), N. impunctatus (Sharp), N. lanei (Hatch), N. sawadai (Watanabe and Shibata), N. scrutator (Gemminger and Harold), N. tachyporoides (Horn), and N. taiwanensis (Shibata).The 10 species of the genus are redescribed; the aedeagus is illustrated for all species, except N. excellens Bernhauer, known only from a unique female. A key is provided to aid in distinguishing the species and the phylogenetic relationships of the species of the genus are discussed.

Polynema pratensiphagum (Walley) is an endoparasitoid of mind eggs (CIBC 1979). Walley (1929) found this species fully developed within the eggs of Lygus pratensis L. deposited in common mullein, Verbascum thapsus L., in Ontario. It has been reported from southwestern Quebec as one of the main egg parasitoids of Lygus lineolaris (Palisot de Beauvois) (Sohati et al. 1989). Andrew et al. (1992) have used another mymarid, Anaphes iole Girault, as a biological control agent against Lygus eggs in California strawberry. Little is known of the overwintering behaviour of mymarids because they are very small and difficult to find. No evidence exists in the literature of mymarids overwintering as adults, and we assume that mymarids overwinter as the last larval instar, or prepupa, in host eggs.

Grasshopper entomopoxviruses are considered to have excellent potential as microbial control agents and are currently undergoing evaluation in a Grasshopper Integrated Pest Management program. Our research has focused on an entomopoxvirus isolated from Melanoplus sanguinipes (F.).

Henry (1975) noted that one characteristic of a microbial control agent of grasshoppers is the potential for mass production. Methods of viral inoculation are varied and depend on the biology of the host and efficiency versus efficacy (Shapiro 1982). In this paper methods of inoculation for mass production of the M. sanguinipes virus in M. sanguinipes are investigated.

The family Acroceridae (Insecta: Diptera; "Small Headed Flies") are a seldom seen yet cosmopolitan group of endoparasitoids of spiders. Recent host and distribution records are presented here for six species of acrocerids: Ogcodes borealis Cole, 1919; Ogcodes pallidipennis (Loew, 1866); Opcodes sp.; Acrocera bimaculata Loew, 1866; Turbopsebius sulphuripes (Loew, 1869); and Exetasis eickstedtae Schlinger, 1972. New hosts for each fly species are; O. borealis—Schizocosa rovneri Uetz and Dondale, 1979, Pardosa spp.; O. pallidipennis—Schizocosa rovneri, Schizocosa spp.; OgcodesSp.—Anyphaena californica (Banks, 1904); Acrocera bimaculata—Coras montanus (Emerton, 1890b); T. sulphuripes—C. montanus.Detailed field measurements and behavioral observations of host spiders and fly development are described and compared with known data. Examination of these comparisons suggests that host–parasitoid relationships follow spider guild associations (i.e. ground/surface dwelling hosts or those building webs in close contact with surfaces), especially with the spider family Agelenidae. These affiliations probably result from a combination of the spider’s web building, web maintenance, hunting behaviors, and fly oviposition activities, which dispose spiders exhibiting these behaviors to greater chances for parasitoidism. These factors act in concert to increase probabilities for host–parasitoid interactions. Compiled data indicate duration of pupation may be related to ambient temperature. Evidence is presented that acrocerid larvae may alter their hosts’ behavior to increase the parasitoids’ probability of survival.

Eleven species of metallic-green Coleophora are recognized in the Nearctic Region, including three that are new: C. ladonia Landry and Wright from Florida, C. ramitella Landry and Wright from the northeastern United States, and C. timarella Landry and Wright from Arizona. Three species are introduced from Europe: C. deauratella Lienig and Zeller, C. mayrella (Hübner), and C. trifolii (Curtis); these are pests of clover seeds. Adults are keyed, described, and illustrated, and the species distributions mapped. Host plants are known for eight of the species, for which larval cases are also illustrated and their life history presented. Nearctic species of metallic-green Coleophora represent a miscellany of unrelated groups, here treated together for convenience. Tentative definitions of informal species groups are provided and phylogenetic relationships of the species are discussed.

Scentless chamomile, Matricaria perforata Mérat [= Matricaria maritima var. agrestis (Knaf) Wilmot], is a widely distributed, rapidly spreading and aggressive weed, especially in the three Prairie Provinces. The seed-feeding weevil, Apion hookeri Kirby (Coleoptera: Curculionidae), is widespread and common in its native range in the Palaearctic. It occurs in such differing climates as the Mediterranean in northern Africa and the boreal climate of western Siberia. The weevil was screened for its host specificity. In the laboratory, females oviposited into the flowers of species in six genera of the tribe Anthemideae, and one species in the tribe Astereae. However, the larvae developed only in Matricaria species, and one adult emerged from stinking mayweed, Anthemis cotula L. In a choice test, ovipositing A. hookeri preferred scentless chamomile 93:1 over stinking mayweed. These results confirm host records in the European literature. It is concluded that A. hookeri is a host-specific and promising agent for the biological control of scentless chamomile.

Thermal responses and temperature-dependent development of laboratory- and field-overwintered eggs of the fruittree leafroller, Archips argyrospilus (Walker), were described using data from constant-temperature laboratory experiments. The time required for completion of hatch of overwintering eggs declined throughout winter until the end of January, after which increasing exposure to natural or artificial cold conditions had minimal effect on median hatching time. There was little year to year variation in response to cold treatments, and thus it was concluded that diapause is terminated by 1 February. Time to hatch decreased with increasing temperature. Distributions of hatch times were near normal, with mean and median development times similar at any given temperature. Development time (days ± SD) at a mean temperature of 20 °C was similar under constant (10.7 ± 1.1) and fluctuating (9.1 ± 1.4) temperature regimes. A nonlinear, six-parameter, biophysical model, fitted (r2 = 0.99) to median hatching rates at 11 temperatures (0.5–30 °C) indicated development was nonlinear below 10 °C, increased linearly between 10 and 25 °C, was maximal at 27.5 °C, and decreased above 27.5 °C. The lower developmental threshold (± SE), estimated to be 4.95 ± 0.54 °C by linear regression (r2 = 0.98) and the x-intercept method, was used to construct a degree-day (DD) model for predicting egg hatch. Median egg development required 154 DD above 4.95 °C. Observed median egg hatch in two different field sites and years was within ± 3 days of the predicted date, using max–min air temperatures, a base temperature of 5 °C, and a starting date of 1 February for accumulating DD. This model should prove useful for scheduling management actions against fruittree leafroller on apples and pears.

In field studies of pheromone-mediated mating disruption of lepidopteran pests, there are several ways to determine if mate location has been disrupted. One indirect method is to count the number of males caught in sticky traps baited with synthetic pheromone. A reduced catch in pheromone-treated plots relative to control plots shows that males were unable to find the source of synthetic pheromone and suggests that mating has been disrupted. More direct methods are: (1) to count the number of males attracted to sticky traps baited with virgin females; or (2) to assess the incidence of mating of (a) feral females collected in light-, bait- or other traps, (b) females caged with males in pheromone-treated areas, or (c) virgin females placed in the field and later retrieved. Females may be tethered with thread to non-sticky traps or partially dealated and placed on a “mating table” from which they cannot escape.

The European corn borer, Ostrinia nubilalis Hübner, continues to be a consistent economic pest of field and sweet corn (Zea mays L.) in the upper midwestem United States. In Minnesota alone, O. nubilalis control costs and losses to sweet corn (ca. 50 630 ha) exceed $5,000,000 annually (Noetzel et al. 1985). Despite recent efforts to implement alternatives (Lewis and Bing 1991; Prokrym et al. 1992; Bartels and Hutchison 1993; Bolin et al. 1993), insecticide control continues to play a central role in O. nubilalis management programs.

We evaluated host discrimination and oviposition restraint in the wasp Praon pequodorum Viereck, a solitary parasitoid of the pea aphid, Acyrthosiphon pisum (Harris). In dichotomous preference tests, wasps attacked more unparasitized than equally available parasitized aphids, and more self-parasitized aphids than aphids parasitized by conspecific females. The conditional probability of a female laying an egg into an attacked aphid was independent of the host type. Host discrimination apparently involves a volatile and individual-specific pheromone marker. Females expecting to compete with other (conspecific) wasps for a limited host supply may ensure possession of the host by self superparasitism. Because host examination requires considerably more time than oviposition in P. pequodorum (and eggs contain few resources), it may be adaptive for a female to lay an egg in an examined host regardless of variations in host quality.

The introduced European weed scentless chamomile, Matricaria perforata Mérat (Asteraceae), is a target for biological control in Canada (Peschken and Sawchyn 1993). As part of this project, the fauna on scentless chamomile in Canada has been investigated (Woo et al. 1991). In 1990, a total of 25 adult Apion weevils were dissected out of 115 flower heads collected at two locations in Antigonish County, Nova Scotia, on 23 August and 4 September. These were identified by D.E. Bright as Apion hookeri Kirby, 1808 (Coleoptera: Curculionidae). The weevil had not been recorded previously in North America.

The two-spotted spider mite, Tetranychus urticae Koch, is an arrhenotokous species (Helle and Bolland 1967). Mated females produce both male and female offspring; unmated females produce only sons. Although there is no “normal” sex ratio for spider mites, a ratio of one male to approximately three females is often found in many tetranychid species (Wrensch 1985). The exact mechanism of the female-biased sex ratio is not fully understood, but previous studies have demonstrated several factors affecting the sex ratio in spider mites. In this report, we analyze the effects of maternal density, age, and the interaction between these factors on female daily fecundity and offspring sex ratio in T. urticae.

Provancher (1872, 1886) described eight species of psyllids from eastern Canada. Their identities have subsequently been confused, ignored, or regarded as doubtful by several authors, primarily because the original descriptions were imprecise and the location of type material unknown [see Hodkinson (1988) for summary]. Van Duzee (1912) excluded these species from his review of the synonymy of the Provancher Hemiptera. I have now examined the Provancher psyllid material deposited in the Department of Biology, University of Laval, Ste-Foy, Quebec, Canada. This paper clarifies the identity of species and designates lectotypes where appropriate. None of the specimens bear locality or host-plant data, although these data are usually given in rudimentary form in the descriptions. Provancher did not state numbers of specimens examined in his descriptions.

New records for non-indigenous species of Hemiptera: Heteroptera continue to be reported from Canada. Schwartz et al. (1991) reported the microphysid Loricula bipunctata (Perris) from Saanichton, British Columbia, and Larivière (1992) reported the occurrence of the nabid Himacerus apterous (Fabricius) from the vicinity of Halifax, Nova Scotia.

Asquith and Lattin (1990) recorded the European anthocorid Brachysteles parvicornis (Costa) from New York, and Noodline, New Jersey. Lattin and Asquith (1991) reported additional material of the species from Maine on Picea glauca (Moench) and from Massachusetts on Pinus rigida Mill. With the latter specimens, the oribatid mite Humerobates rostrolamellatus Grandjean was beaten from the trees along with the bug. This is a cosmopolitan mite that occurs on trees and is found in Europe. Pericart (1972), citing Carayon, stated that Brachysteles parvicornis fed upon oribatid mites found on trees. Pericart provided a detailed account of this species of anthocorid in Europe. Little is known of its habits in North America except that it appears to be found on conifers and seems to be associated with the oribatid mite mentioned above. Pericart (1972) reported other hosts in Europe so the bug may be found on non-conifer hosts as well. There is a brachypterous form but, thus far, only fully winged adults have been collected in North America.

Effective management of the interactions within the mite community is critical to biological control of economically damaging phytophagous mites such as Panonychus ulmi Koch (Tetranychidae) (Clements and Harmsen 1990). Although much is known about the potential role of phytoseiid mites in controlling P. ulmi (Dover et al. 1979), mites from at least seven other families may be present in apple orchards (Thistlewood 1991). Stigmaeid mites are predators which may play a beneficial role in biological control in conjunction with phytoseiids (Clements and Harmsen 1992). Eriophyid mites are phytophagous but seldom cause economic damage, and may compete with tetranychids and provide alternative food for predators of tetranychids (Croft and Hoying 1977).

Western flower thrips, Frankliniella occidentalis (Pergande), originally distributed throughout western North America (Bryan and Smith 1956), have since spread to greenhouses in the eastern United States and Canada, and to many other parts of the world (Brodsgaard 1989). Populations have established outdoors in the southeastern United States (Chamberlin et al. 1992) and in several other warm regions of the world (Brodsgaard 1993). but have failed to establish in Ontario (Broadbent and Hunt 1991) and the northern parts of Europe (Brodsgaard 1993). We have not found reports of western flower thrips overwintering outdoors in the northeastern United States.

The effect of long-term storage on the activity of biological control products, particularly those containing nuclear polyhedrosis viruses (NPVs), has not been extensively studied. Most investigations involving viral insecticides have dealt with their thermal stability (Stuermer and Bullock 1968; Dulmage and Burgerjohn 1977; McLeod et al. 1977; Ignoffo and Couch 1981). Freeze-dried and air-dried powdered preparations of gypsy moth, Lymantria dispar L., NPV show little reduction in potency after storage at 4°C for 10 months and 3 months, respectively. Consequently, it was recommended that gypsy moth NPV be stored in either state at 4°C to maintain acceptable activity (Lewis and Rollinson 1978). TM BioControl-1, the viral product for control of the Douglas-fir tussock moth, Orgyia pseudotsugata (McDunnough), registered and used in the United States, has been shown to have a shelf life of 5 years if stored in a cool, dry place (Martignoni 1978). Virtuss is the NPV product manufactured in Canada, in the whitemarked tussock moth, O. leucostigma (J.E. Smith), since 1975 by the Forest Pest Management Institute, Forestry Canada, Sault Ste. Marie, Ont., for the control of the Douglas-fir tussock moth. It is routinely stored at 4°C in anticipation of tussock moth outbreaks and has been successfully used in the control of outbreaks of Douglas-fir tussock moth in Canada (Otvos et al. 1987). If these, or any other viral products are to be successful commercially, more information is required on the effect of storage on viral potency. Similarly, little information is known of the cumulative effects of the mechanical processes of lyophilization and milling on the biological activity of viral products. This note reports on the effects of mechanical processing and storage on Virtuss. Our results show that, although there is no immediate effect of mechanical processing, there can be substantial loss of biological activity of this product after 2 years of storage.