The relationship between the distribution of Panonychus ulmi (Koch) and cluster size was examined. As the population intensity increased, P. ulmi numbers and distribution tended to be more closely related to the number of leaves in a cluster.

The first adult generation of Winthemia rufopicta (Big.) emerged during April in North Carolina, males preceding the females by about a week. This was several weeks prior to the occurrence of large larvae of Heliothis zea (Boddie) and H. virescens (Fab.), two commonly recorded hosts of W. rufopicta. The average female, after a pre-ovipositional period of several days, deposited about 60 eggs over a further several days. The sex ratio was normally unity, with the exception that flies overwintered in the field showed a predominance of males.

Populations of W. rufopicta declined in spring, apparently from a shortage of hosts, then slowly built up through several overlapping generations: developmental rates at different temperatures are indicated. In the fall, local host concentrations were more frequent, and parasitism of Heliothis hosts on tobacco occurred consistently and sometimes reached high levels. Parasites overwintered as fully grown diapausing maggots in shallow cells in the soil.

Experimental populations of Heliothis spp. (mainly H. virescens) maintained on tobacco were not parasitized by W. rufopicta until late in the season. Temporal and spatial interactions between host and parasite populations at that time are discussed.

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.

Laboratory studies of large Diptera, viz. Stomoxys calcitrans (L.) and Musca domestica (L.), necessitated the development of an aspirator that would be more efficient than the conventional one and which prevents associated debris from entering the operator's lungs. A suitable device was made by attaching a portable, lightweight vacuum cleaner to the mouth piece of the aspirator (Fig. 1). The size of the collecting jar can be varied to suit the size of the sample. This apparatus, which is easy to use (Fig. 2), and does not damage the insects being collected, saves considerable time. The aspirator may be useful for collecting from an assortment of dirty habitats (Wiens and Burgess 1972) as well as other scaly-winged insects. It may be adapted for use in the field by connecting it to a portable generator.

Chrysocharis laricinellae (Ratz.) from Austria, Sweden, England, and Wisconsin, some of which were thought possibly different species, were crossed. Hybrid sex ratios in this arrhenotokous species were similar to parental types, indicating conspecificity. English and Wisconsin strains tended toward darker legs and female scapes.

Methoprene, when incorporated into the food of laying hens at concentrations of 0.005 and 0.01%, produced 70.9 and 99.3% larval mortality, respectively, among house flies (Musca domestica L.) reared in the resultant poultry droppings. Exposure to the treated diet did not produce any weight loss in the chickens. However, it was not effective when the poultry droppings were treated topically under field conditions. In laboratory studies, when incorporated with moistened droppings, concentrations of 0.001 and 0.0001% produced complete larval mortality throughout a 7-day exposure period, though only 98% mortality was achieved on the first day at the higher concentration. Concentrations of 0.5 and 1.08 of the compound in fly food produced only a low order of sterility. Topical applications produced a low order of sterility except in the insecticide-susceptible females.

The depressed flour beetle, Palorus subdepressus (Wollaston), was found in southern Manitoba during a survey of the insect fauna of hog barns in April 1974. This is the first record for this species in Canada. Adults and larvae were obtained from residues of coarsely ground feed on the floor of the hog pens. Dr. E. C. Becker of the Biosystematics Research Institute, Ottawa, kindly confirmed the identification of the adults and two specimens were retained for the Canadian National Collection. A culture has been established at the Research Station, Winnipeg.

Long-day (LD = 18 light: 6 dark) and short-day (SD = 12L:12D) photoperiodic treatments of various sequences and durations were applied to Coleophora laricella (Hbn.) larvae at 20 °C. Continuous development did not occur at either constant LD or SD. At LD, growth of young larvae was slow and was suspended in the late second or early third instar. At SD, young larvae developed rapidly but entered diapause in the late third instar. Pupation occurred when LD followed a period at SD. Timing and synchrony of pupation in a population were shown to be controllable by specific LD and SD sequences.

To relate the various details of the cluster fly life cycle which have recently appeared in the literature, a preliminary mathematical model is constructed When used to interpret the population data of De Coursey, the relationships of the model were shown to be at least qualitatively sound. From an examination of the parameters which modify the components of the model, some possible control measures are suggested.

Short-term interactions of the polyphagous tachinid Winthemia rufopicta (Big.) with its hosts, especially Heliothis zea (Boddie) and H. virescens (Fab.), are considered.

Within a given host species, interacting factors fall into three groups: (1) factors that have little influence on parasite oviposition, or cause little parasite mortality (host responses to ovipositing parasites, previous parasitism, firmness of attachment of eggs and, in the populations studied here, direct competition with other insect parasites); (2) factors that may account for significant limitation of oviposition (habitat, diel activity, and seasonal occurrence of a given host, and species preference of the parasite) or that cause significant parasite mortality (destruction by the host and other mortality of hatching maggots, which in turn depends partly on the position of eggs on the host): and (3) factors that can vary widely in a given host species and are therefore of great potential importance. These are: (a) host feeding behaviour—initial parasitism of H. zea, for example, varies from negligible levels for larvae concealed in corn ears to sometimes very high levels for larvae feeding openly on tobacco leaves; (b) host size—smaller larvae (especially penultimate compared with final instars) receive fewer ovipositions, and fewer eggs per oviposition; (c) host moulting—surface-deposited eggs are lost if the host moults before they hatch, but the rate of moulting varies with instar and foodplant, and interacts differently with parasite egg incubation times at different temperatures (most eggs are lost except in final instars); (d) intraspecific competition—depends on parasite and host densities, but reaches the highest levels in the fall; (e) competition with host pathogens—parasites may be killed during development if the host dies from pathogens.

For different hosts, family, size, surface quality, and spatial and temporal availability are known to have divergent influences on the levels of parasitism, but many other interactions are probably important.

The interpretation of records of total or of successful parasitism in host samples is considered—behavioural, developmental, and numerical interactions may make conclusions drawn from such records unreliable. In particular, levels of parasitism may change very rapidly as host or parasite populations develop; laboratory rearing may distort recorded levels of successful parasitism; and the proportion of attacked hosts that produce parasites, and the number of parasites produced by each host, normally varies directly with the number of eggs per host even when this is large.

The biology of Urophora cardui (L.) (Diptera: Tephritidae) and its suitability as a biocontrol agent for Canada thistle (Cirsium arvense (L.) Scop.) were investigated. The incubation period of the eggs was 4.3 days at 27 °C. Crowding did not significantly reduce the longevity of the adults, the number of eggs laid, or the egg hatch. U. cardui overwinters as a mature larva in the gall but pupation and further development ensue when the larvae are exposed to air by opening the gall. The roots of single and double-galled plants weighed 65 and 78% less and the combined weights of the stem and leaves 47 and 58% less respectively than plants without galls. U. cardui is monophagous: it oviposits into Canada thistle and if kept without this host, into the closely related weeds Cirsium vulgare (Savi) Ten. and Carduus acanthoides L. U. cardui is a promising biological control agent and should be released in Canada.

Canada thistle (Cirsium arvense (L.) Scop.) is a widespread noxious weed in Canada and the northern United States. This paper reports on the biology of Urophora cardui (L.), a European tephritid, and its suitability for introduction into Canada to aid in the control of the thistle.

Onthophagus nuchicornis (Linnaeus), an accidentally introduced dung beetle, is the only scarabaeine species encountered commonly in cattle dung in British Columbia. Its dung burial efficiency and its potential for inhibiting development of coprophagous fly larvae were measured in greenhouse experiments.

The beetles buried dung most efficiently when they were present in the ratio of one pair per 40–50 g of feces. Higher or lower rates of infestation resulted in reduced burial Survival of fly larvae was inversely related to the numbers of brood balls constructed by the beetles, and hence to the amount of dung buried. Beetle activity in the field probably has little harmful effect on the dung-breeding horn fly as the beetles cease burial activity before midsummer, when horn flies reach their greatest numbers, and as they do not bury significant amounts of dung in pastures.

The desirability and possibility of introducing exotic dung beetles into British Columbia for fly control is discussed.

Virgin females of Tenebrio molitor L. initiate vitellogenesis about 2 days after the imaginal moult. During the first 6 days after the imaginal moult, each female with males matured on the average 41 eggs and each virgin matured 29 eggs. Stimuli associated with copulation and(or) insemination apparently are not required to initiate vitellogenesis, but do enhance the rate of oocyte maturation. Mated females lay their first eggs on the fourth day and virgin females about 1 day later. After the sixth day, mated females matured oocytes at about the same rate as before this time, whereas oocyte production is almost completely inhibited in virgins. Mated females also laid about 7.5 times as many eggs and accumulated an average of 40% fewer eggs in their reproductive systems than virgins. It is suggested that stimuli associated with copulation and(or) insemination enhance oviposition per se in mated females, that the accumulation of eggs in the reproductive systems slows further development of oocytes in virgins, and that the inhibition of vitellogenesis in virgins occurs at, or soon after, the time the first gonadotropic cycle is completed. A system for classifying stages of oocyte maturation in T. molitor is described.

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.

Laboratory and field experiments indicate that the female spruce budworm (Choristoneura fumiferana (Clem.)) pupal stadium requires approximately 122C degree-days above a threshold of 7.2 °C (45°F), the male 124. Emergence time on any given day depends on temperature but is independent of photoperiod. Under field conditions male and female budworm mate only once per 24-h period. In the laboratory under continuous illumination females mate repeatedly and males readily mate a second time within a few hours, but the duration of the second copulation is abnormally long. The probability of multiple matings under field conditions is reduced by the restricted period of sexual activity coupled with the duration of copulation and the lower competitiveness of mated insects. Antennae are essential to the male for successful copulation.

Field trials of the synthetic bark-beetle pheromone frontalin demonstrated that lines of single, baited spruce trees, in or near Dendroctonus rufipennis infestations, resulted in concentrated beetle attacks on trees in a strip 2 chains (40 m) wide on either side of the lines of baited trees. Pre-flight insecticide (Lindane) application killed the beetles and prevented tree mortality. Post-attack arboricide (Silvisar) treatment killed most parent beetles and brood under the bark. A predator, Thanasimus undatulus, also was aggregated at frontalin-baited trees. This application of pheromone shows promise of becoming a forest management tool to concentrate beetle attacks in partly infested stands prior to logging.

(1) Crude extracts prepared from the silk glands of the silkworm, Bombyx mori L. contain trehalase activity. (2) Trehalase in the silk glands has a pH of 5.5 and a Km of 0.71 mM. The activity of the enzyme is inhibited by divalent cations such as Mn, Cu, and Zn. (3) By histochemical methods, it is shown that trehalase is localized in the periphery of the silk gland cells, especially in the tunica propria and tunica intima. (4) Trehalase activity is low in fifth instar and increases greatly in spinning stages, after which the activity decreases.

The subgenus Hagenomyia, of the genus Simulium, was erected by Shewell (1959) for Simulium pictipes Hagen, 1880, and S. longistylatum Shewell, 1959. Unfortunately, Hagenomyia Shewell is a junior homonym of Hagenomyia Banks (1911, p. 8) created for H. tristis (Hagen), an African myrmeleontid (Neuroptera). This matter was drawn to the attention of Mr. Shewell some time ago, and he has requested that I act on it.

This study had dual objectives: to select a series of insecticides toxic to the bertha armyworm, Mamestra configurata (Walk.), and to determine susceptibility of the various developmental stages to insecticides. Pupae were collected from infested rapeseed fields in Alberta and a laboratory rearing procedure suitable for production of large numbers of insects was devised. The direct contact toxicity of 50 insecticides to third-stage larvae was assessed. Methomyl and DDT were included as standard insecticides. None of the experimental insecticides was as toxic as methomyl but about one half were more toxic than DDT. Tests with representative organochlorine, organophosphorus, and carbamate insecticides indicated that all caused rapid knockdown of third-stage larvae. There was no evidence of subsequent recovery. After the life history of the bertha armyworm under controlled environmental conditions was determined, tests were conducted to ascertain the susceptibility of the various developmental stages to methomyl, chlorpyrifos, leptophos, and methidathion. Eggs and first and second stage larvae were more susceptible to direct contact applications of the insecticides than were the later larval stages, pupae, and adults.

The area of distribution of Thymelicus lineola (Ochs.) now includes much of agricultural Quebec. Several localized, low density populations were observed, especially south of the St. Lawrence River. Heavy infestations were found in the regions of Lac St-Jean, Joliette, and Abitibi–Témiscamingue.