The effect of host age of the cabbage looper, Trichoplusia ni (Hübner), on ovipositional rate and successful parasitism by Hyposoter exiguae (Viereck), a solitary endoparasitoid was investigated. Success in parasitism of T. ni was correlated with host age. Successful parasitism of hosts exposed as first, second, or early third instar larvae, ranged from 83 to 88%. A decline in parasitism was observed for the remaining instars with a low of 27% for mid-fifth instar larvae.

A different relationship between host age and successful parasitism was observed in tests where all five instars of the host were presented to the parasitoid simultaneously. Successful parasitism was highest among second and third instars, approximately 75% for both, and lowest for fifth and first instars, 10% and 30%, respectively. A significantly higher rate of mortality was found for first instar hosts.

The ovipositional rate of H. exiguae was related to host age. The parasitoid deposited an average of 2.3 and 1.3 eggs per 24 h in first and second instar T. ni, respectively The number of eggs/host and degree of superparasitism declined in older individuals and differed statistically for each instar. The percentage parasitism differed statistically for all but first and second instar larvae.

In the early 19th century, malaria was indigenous in Upper Canada (Ontario), but indigenous infection has not been seen in Canada since about 1909. For many years mosquitoes were regarded principally as harmless pests of man and domestic animals until the recognition of a number of mosquito-borne viruses. At present, mosquitoes in Canada are known to be involved in the maintenance or spread of at least seven arboviruses. One of these viruses, western equine encephalomyelitis, occurs in epidemics in man and horses at irregular intervals in the western provinces. The extent to which the other arboviruses might cause disease in man or domestic animals in Canada is unknown at present but California encephalitis virus infection rates can be high in human residents of central Saskatchewan, central Alberta, and southern British Columbia. On the basis of observations made in the United States, St. Louis encephalitis virus could pose a threat to public health in Canada whereas the Cache Valley virus might involve livestock. Even if man and livestock are not involved at present in epidemics of disease due to these viruses, the presence of the viruses and their vectors should be of concern. Epidemics could arise either from amplification of causal viruses already present in indigenous foci or by amplification of viruses from new enzootic foci recently established by extension of the geographic ranges of the viruses. Evidence indicating which category each of the known viruses in Saskatchewan belongs to is briefly reviewed. Japanese B encephalitis virus has not yet been seen in Canada but the environmental prerequisites for an epidemic or epizootic due to this virus appear to be present and awaiting the arrival of the virus.

Queen honey bees were reared in the laboratory in cages by small groups of worker bees; the queens were then introduced to small nuclei to test their acceptance, mating ability, brood patterns, and brood production. Later, certain morphological and anatomical characters were measured. No significant differences in sealed brood, total brood, or in selected morphological characters were found between control queens and those reared in the laboratory. The possible economic aspects of this cage rearing method are discussed.

Plecia myersi n. sp. is described from remains found in Canadian Amber, of Upper Cretaceous age, from Cedar Lake, Manitoba. This specimen is the oldest positively identified fossil of the Bibionidae, and demonstrates the family existed in the Mesozoic Era in a form much like modern species.

Amylopectin added to a sugar-free wheat-germ diet was equal to or better than sucrose as a carbohydrate source, and appears to be readily utilized by the eastern spruce budworm (Choristoneura fumiferana (Clem.)). Larval growth on diets containing dextrins or potato starch shows that they are partly utilized. Starches from other sources, including those isolated from mature balsam fir (Abies balsamea (L.) Mill.) or white spruce (Picea glauca (Moench) Voss) needles, are not utilized to any extent, on the basis of larval growth on diets to which they have been added.

Sixth-instar budworm reared on artificial diets contain amylase(s) in midgut and salivary gland homogenates, which show a low rate of digestion of starches from host foliage. However, the presence of appreciable starch in frass from foliage-fed insects and the apparent low utilizability of foliar starch indicate that the latter is not an important nutrient for the budworm under natural conditions.

Dieldrin resistance has been confirmed in adults of the cabbage maggot, Hylemya brassicae (Bouché), from the Edmonton area of Alberta. The resistance of this heterogeneous strain had increased from 30% in 1967 to about 80% in 1972. The change in resistance is attributed to selection pressures on H. brassicae by dieldrin residues in the soil. Dieldrin resistance is suspected in the Fincastle area but was not detected in the Lethbridge area.

Toxicity data were established for the Lethbridge and Edmonton strains with alternative insecticides currently recommended in Alberta. There were no differences in the toxicity of the alternative insecticides between strains. Carbofuran and chlorfenvinphos were equal to dieldrin whereas fensulfothion was about six times less effective.

A discriminating dose technique for detecting changes in insecticide susceptibility is discussed.

Concentrations of the insecticide fenitrothion in water varied greatly among streams, depending upon spray history and weather. Sprays at 3 oz/ac (210 g/ha) resulted in measurable concentrations in streams as far as 2.5 mi (4 km) from the sprayed area. Concentrations (usually < 15 ppb) diminished quickly in fast flowing streams, and still faster when a spate followed spray application.

Kills of arthropods in three streams containing fenitrothion up to 6.38 ppb were measured using drift nets. Stoneflies and some species of mayflies were most affected. The drift responses of various taxa to the insecticide and to stream discharge are documented. The benthos was not seriously depleted.

On Scots pine, Neodiprion sertifer prefers the lowermost needle of fascicles on the distal one-third of shoots for oviposition. The amount of divergence between needles in a fascicle may influence the selection of oviposition sites, as the needles were further apart in egg-bearing fascicles. The interior diameter of resin canals was significantly greater on egg-bearing than non-egg-bearing needles.

The toxicity of a number of insecticides was tested against three species of springtails (Collembola), Folsomia candida (Willem), Onychiurus justi porteri (Denis), and Hypogastrura armata (Nicolet), which were cultured in the laboratory. Treatment was accomplished by incorporating the insecticide into moist Plainfield sand and exposing the springtails for 24 h on this substrate. Generally, the order of toxicity of the insecticides to all three species was: Counter® (phosphorodithioc acid S- (tertbutylthio) methyl O,O diethyl ester) > phorate > carbofuran > heptachlor > methomyl > chlorfenvinphos. Acephate, leptophos, p, p′-DDT, and chlordimeform were of low toxicity to all species. More significantly, however, there were large interspecific differences in susceptibility to insecticides; fensulfothion was virtually non-toxic to O. j. porteri (LD50 > 80 p.p.m.) but highly toxic to F. candida (LD50 = 0.1 p.p.m.). Results of these tests suggest that extrapolation of toxicity data from one species of springtail to other species would be unwarranted.

Pieris occidentalis nelsoni W. H. Edwards from Fairbanks, Alaska, was reared under a variety of photoperiod–temperature regimes. The source population is presumably univoltine and monophenic, with a phenotype resembling the vernal one produced by multivoltine, diphenic P. o. occidentalis Reakirt in Colorado and California. Photoperiods of 10 or 15 h produced 100% diapause pupae at 15 °C and circa 65% at 25 °C. Under continuous light 22% diapaused at 15 °C and < 1% at 25 °C. About 20% of non-diapause pupae produced adults resembling the estival phenotype of P. o. occidentalis, which is unknown in wild P. o. nelsoni. Although nelsoni is more likely to diapause than the nominate subspecies from the Sierra Nevada, its potential for direct development and polyphenism is interpreted as evidence that it is derived from a multivoltine ancestor.

Cylindrical traps with screen cones at the ends baited with virgin females and placed in rape fields about 1 m above ground level were effective in trapping males of the bertha armyworm. Males were most active between 0330 and 0430 h M.D.T. and moved precisely to confined females. Virgin females became attractive 1 day after emergence and remained attractive for at least 7 days. Trapping was an effective method for rapidly determining the presence of bertha armyworm.