The number of instars of larvae of the alfalfa leafcutter bee, Megachile rotundata (F.), was determined by direct observation, frequency distribution plots, and linear regression of head-capsule measurements. For all three methods, developmental polymorphism was observed; larvae were grouped according to the number of instars. The majority of larvae (77%) had four larval instars and the remainder had five. Mortality of bee larvae, apparently a result of physical injury during measurement of head-capsule width, was high but results were based on data for 259 individuals that completed development to the prepupal (= pharate pupa) stage. Direct observation of larval moults was found to be the only accurate method for determining instar designation but analysis of head-capsule width did describe the number of instars present in a population and provided estimates of head-capsule width for each instar. A morphological key for separation among four instars is presented as a practical alternative for instar determination in field studies.

A description is given for the male, female, and larva of Farula praelonga sp. nov. and for the female and larva of Neothremma genella Denning. Farula praelonga sp. nov. is distinctive in having an exceptionally long internal branch of segment X. The female of Neothremma genella is the only female yet known in that genus to have greatly reduced ventrolateral lobes of sternum IX. Modifications are made to the keys previously published for adults of Farula and Neothremma to incorporate this new information. These two species occur together in abundance; they are univoltine and have emergence periods 6 months apart.

A distribution study of stored-product and other insects in unswept, empty farm granaries was conducted in Manitoba in 1981, in Saskatchewan in 1982, and in Alberta in 1984.

Thirteen species of stored-product insects were found in Manitoba and Saskatchewan and 12 in Alberta, indicating uniform geographical distribution among the number of pest species throughout the prairies. The most common was Tribolium audax Halstead, followed by Cryptolestes ferrugineus (Stephens) and Tenebrio molitor L. Nine fungus-feeding species were found in Manitoba, 12 in Saskatchewan, and 12 in Alberta. The most common fungus feeders were Lathridius minutus (L.), Corticarina cavicollis Mann., Cryptophagus varus W.&C., and Corticaria serrata (Paykull). Five non-stored product species of insects that were scavengers, predators, or were sheltering in the granaries were found in Manitoba, 31 in Saskatchewan, and 10 in Alberta.

The distribution of six stored-product species, two fungus-feeding species, and one scavenger did not show a uniform abundance in the three prairie provinces, either in their distribution on farms or in granaries.

Theridion strepitus sp. nov. is described from lava tube caves from Isla Santa Cruz, Galápagos, Ecuador. It is the only species known in this worldwide genus that is eyeless and it is the only Galápagos species that has stridulatory picks on the male abdomen. The stridulatory apparatus demonstrates that the species is not a descendant from the other Theridion species known in the Galápagos, but is probably a relict of a lineage now extinct there in epigean habitats.

Descriptions are given of adults of three Limoniidae (Tipuloidea) found preserved in Canadian amber (Upper Cretaceous): Trichoneura (Trichoneura) canadensis sp. nov.; Macalpina incomparabilis gen. nov., sp. nov.; and Limonia albertensis sp. nov.

A simple experimental device has been described for controlling relative humidity (RH) using saturated salt solutions. This device was suitable for studies requiring a 14–82% RH (± 3%) at 27 ± 0.7°C. The RH and temperature set points were not affected by the presence of grasshoppers. Perturbations of 1.5 min due to daily insect provisioning introduced a 9- to 60-min disturbance of the RH and temperature equilibria in the chambers containing NaCl and LiCl, and a 7.5-h disturbance in the MgCl2 chamber.

In laboratory tests, Melanoplus sanguinipes (Fab.) was susceptible to infection by Beauveria bassiana (Bals.) Vuillemin conidia. Infection occurred independently of the relative humidity (RH) (12, 33, 76, 100% RH). No significant difference was observed in the final percentage mortality of the treated grasshoppers and in the lethal times (LT50)(P > 0.05) under the RH conditions studied. However, the daily rate of mortality after treatment was higher at 76% RH than at 33% RH. High natural mortality occurred at 100% RH.

At 100% RH, treatment with B. bassiana was associated with an outgrowth of microorganism that created septicemic conditions in the absence of the characteristic symptoms of mycosis. Below 100% RH, mycelial growth on cadavers was never observed, even though partial or total insect mummification occurred, and a pink body coloration on approximately 80% of the insects indicated Beauveria as the killing agent. Once transferred to 100% RH, no more than 5% of the treated grasshoppers exhibited external mycelial growth.

The microenvironment at the cuticular level of the grasshopper allows expression of conidial pathogenicity regardless of ambient RH. Hence, together, these observations suggest the feasibility of field testing with B. bassiana as a bioinsecticide against M. sanguinipes in semi-arid climatic areas.

Morphometric analysis was studied on the measurements of the forewings, ovipositor, hind tibia, and antenna of female Anagrus giraulti Crawford reared from the following hosts: Circulifer tenellus Baker, Empoasca fabae (Harris), and Scaphytopius nitridus (DeLong). Results showed that A. giraulti emerging from E. fabae had significantly shorter antennal segments, ovipositor, and tibia III than those reared from the other two host species. Host eggs of C. tenellus produced female A. giraulti with significantly longer wing lengths than did the other two species and wider wing widths than did E. fabae.

A key is given for 16 species in the genus Macrosiphoniella Del Guercio in America north of Mexico, including one new species from Manitoba, Macrosiphoniella paucisetosa sp.nov. from Artemisia spp. An annotated list is provided which includes tentative identification of M. oblonga (Mordvilko) intercepted on plants of Chrysanthemum imported into the United States of America from Europe.

The larva of Helluomorphoides praeustus bicolor Harris is described and illustrated from two specimens. This is the first larva of Helluomorphoides Ball, a New World genus belonging to the tribe Helluonini, described although parts of an undetermined species of the genus were figured by Thompson (1979). Analysis of larval characters of the tribes Helluonini and Anthiini supports the hypothesis that these two groups are closely related. At least three autapomorphic character states are identified for members of Helluonini and Anthiini: the antacoria between the antennomeres II and III is represented by a suture or is absent; the stipes has a medial excrescence which may or may not be fused with the first galeomere; and the urogomphi are stout, fixed dorsally to the ninth tergite, and possess numerous long setae in the first instar. The sister group of the Helluonini–Anthiini lineage could not be identified but a number of the synapomorphies of this complex also occur in the Galeritini and Pseudomorphini.

The status of Anarta cordigera (Thunberg, 1788), formerly treated as a circumboreal holarctic species, is reassessed in the light of characters of the male vesica and female bursa copulatrix. Populations are arranged in four species: A. cordigera in Europe; A. carbonaria Christoph, 1893 in Siberia and the Far East; A. luteola Grote and Robinson, 1865 in North America; and A. macrostigma Lafontaine and Mikkola, new species, in western North America. Adults and genitalia are illustrated for the four species.

Spruce budworm larvae were bioassayed against Bacillus thuringiensis Berliner to study the effect of temperature on the expression of toxicity. Temperatures between 16 and 28°C did not affect the ultimate level of toxicity (LC50). However, LT50’s increased from 2–8 days at 28°C to 11–20 days at 16°C, depending on concentration of the pathogen. When larvae were force-fed with a single dose, temperature had a similar effect on the time course of mortality without affecting the level of mortality. Feeding inhibition of force-fed larvae commenced immediately after dosing. Larvae that did not recover died without further feeding, even at lower temperatures when death occurred 2–3 weeks after dosing. Recovering larvae resumed feeding after 2 (28°C) to 6 (13°C) days. Recovered larvae took longer to develop and produced lighter pupae than untreated larvae. Our data suggest that temperature-dependent feeding and recovery did not contribute to quicker death at higher temperatures. Expression of the toxin itself appears to depend on temperature, possibly through the influence of temperature on metabolic rate of affected gut cells. Implications of these findings for the efficacy of spruce budworm control operations are discussed.

Bacillus thuringiensis Berliner is registered for control of several defoliating forest insects, including the spruce budworm (Choristoneura fumiferana Clem.), jackpine budworm (C. pinus Freeman), and gypsy moth (Lymantria dispar L.) (Morris et al. 1986). Product labels and user guidelines of several manufacturers recommend application to dry foliage for best results. Efficacy is presumably reduced when foliage is wet from dew or precipitation. Possible causes are lower impaction efficiency of spray droplets on the wet leaf surface (Spillman 1984) and dilution of the active ingredient. I compared the efficacy of B. thuringiensis applied to wet and dry balsam fir foliage (Abies balsamea L.) in a laboratory bioassay with larvae of the spruce budwom, Choristoneura fumiferana.

The Colorado potato beetle, Leptinotarsa decemlineata (Say), has a genetic system of great diversity and dynamic nature. This results in an enormous adaptability to a range of habitat conditions. Its genetic diversity is exemplified by the existence of color mutants (Tower 1906; Boiteau 1980, 1985).

In the summer of 1986, a red-body mutant male beetle was found in a potato field on the grounds of the Research Station in Fredericton, N.B., Canada. No other red beetles could be found in spite of frequent monitoring of beetle populations. The specimen retains the normal black maculation throughout but all pale yellow to flavous areas of normal beetles have been replaced by the color red (Scarlet 19/3 of the Royal Horticultural Society Colour Charts, 1942). To the best of my knowledge, this is the first report of a red Colorado potato beetle in Canada. Previously, red potato beetles had only been reported from the semi-desertic area of Toluca, near Mexico City (Tower 1906).