Several species of wireworms were attracted to germinating wheat, air from flasks of germinating wheat, decomposing oatmeal, commercial CO2 and, in addition, germinating seeds of eight other cultivated plant species. Larvae located a biological or experimental source of CO2 by a directed movement along CO2 gradients, from distances up to 20 cm.

Methods and apparatus for measuring small CO2 gradients, using gas chromatography and mass spectrometry, are described. Ctenicera destructor (Brown) larvae apparently responded to CO2 gradients between glass plates, that ascended on the average by 0.002% (soil) and 0.005% (agar)/cm over a distance of from 12 to 16 cm. The "sensitivity threshold" was calculated as being 1–2 ppm over the distance involved in one deflection of the head during klinotactic orientation. Attractancy was observed within a range of CO2 concentration from about 0.036% to 1.5%. Repellent effects did not appear to be only related to concentration, but possibly were due to steepness of the gradient and(or) previous exposure to CO2.

Passing an air stream from germinating grain over a KOH solution eliminated the attractancy of the grain by removing the CO2 and possibly other undetected attractants. A small percentage of C. destructor larvae apparently oriented to an ethylene source, but it was concluded the CO2 was the most important if not the only attractant from germinating wheat seeds.

Two mature male adults of Anax Junius were seen in Ontario exceptionally early in spring, before emergence had begun locally, and very soon after an episode of unseasonably warm weather which was associated with the arrival from Texas of a low-pressure system.

The effect of coprophilic insects on horn fly (Haematobia irritans irritans (L.)) production from cattle dung was measured at Kamloops, B.C. Adult female flies were trapped after oviposition on fresh dung pads during 24-h sample periods. The pads were then either exposed to field insects for 24 h or covered with frames excluding insects for the same period, and removed to a greenhouse where all fauna emerged.

Horn fly females did not show a definite diurnal rhythm in oviposition. There was a single peak in adult abundance during the summer. Numbers of progeny produced per female fly from covered pads showed an apparent peak from 0300 to 0600 h while lowest numbers were produced in the early evening. Throughout the summer the progeny production from pads exposed to other insects was uniformly and significantly lower than from covered pads of the same age. Insects chiefly responsible for this suppression are probably the predators Philonthus cruentatus Gmelin, Sphaeridium scarabaeoides (L.), and S. lunatum (F.). Parasites of horn fly and dung-burying beetles (Scarabaeinae) are scarce and so there is still plenty of opportunity for manipulation of horn fly populations by use of other biological agents.

Codling moth, Laspeyresia pomonella (L.), injury in a 14-ha apple orchard gradually increased in 1973 and 1974 despite the presence of 480 sex pheromone traps (1 mg trans-8, trans-10, dodecadien-1-ol per trap). Percentage injured fruit at harvest was 0.00075, 0.0062, and 0,033 in 1972, 1973, and 1974, respectively. Numbers of wild male moths trapped increased from 3e in 1973 to 64 in 1974.

A brief history of the importance attributed to red wood ants in Europe and the outstanding qualities of three species, Formica lugubris Zett., F. polyctena (Foerst.), and F. aquilonia Yarr., are presented. The reasons for choosing F. lugubris as a suitable species for introduction to Canada are given. The collecting in Italy, shipping by air to Canada, and eventual release in Quebec is discussed. In conclusion it is stated that the establishment and acclimatization of this species in Quebec was successful, and that increased reproduction and spread is anticipated.

This paper presents a sampling plan for estimating populations of Hypera postica (Gyll). cocoons in alfalfa, and of the principal mortality factors during this stage. The plan provides for samples in foliage and ground litter. For samples in foliage, where two-thirds of the cocoons are found, the most appropriate sample unit is a bouquet of 6 stems; for typical weevil densities, estimates with acceptable precision may be obtained by taking 25 bouquets at random from within a field. For litter samples, the appropriate sample unit is a quarter ft2 (232 cm2); acceptably precise estimates may be obtained by taking 20 such units at random from within a field. Total cost for a combined sample is 3.9 man-hours.

The pattern of counts, both in foliage and ground litter, was well described by the negative binomial distribution.

Bacillus thuringiensis (B.t.) + sublethal doses of the organophosphates fenitrothion or Orthene® were aerially applied to spruce budworm infested white spruce and balsam fir trees. B.t. + fenitrothion applied at 10 BIU + 17.5 g active ingredient in 4.71./ha (4 BIU + 0.25 oz in 0.5 gal/acre) and depositing at 1.5 to 3.0 BIU + 2.1 to 4.9 g/ha (0.03 to 0.07 oz/acre) did not protect the trees in the year of application owing to too low application rates but apparently gave good protection 1 year later without further treatment. A B.t. + Orthene combination applied at 20 BIU + 42 g/ha (8 BIU + 0.6 oz/acre) and depositing at the rate of 6.9 BIU + 12.6 g/ha (2.29 BIU + 0.18 oz/acre) provided good protection for both tree species in the year of spray.

Moth emergence was substantially reduced by 20 to 30 BIU B.t. + Orthene combination treatment. Thuricide fenitrothion, Dipel fenitrothion, and 30 BIU Orthene treatments reduced oviposition rate by at least 62%, 47%, and 47%, respectively. B,t. + a low dose of Orthene apparently had no major destructive effects on larval, pupal, or egg parasites whereas B.t. + a low dose of fenitrothion seriously reduced egg parasitism.

The data indicate the possibility of using B.t. in combination with low doses of chemical insecticides against the spruce budworm as an alternative to high doses of chemical insecticides alone.

Well-fed, mated female spruce budworm (Choristoneura fumiferana (Clem.)) show little activity during the first 24 h after emergence. During the second 24 h they lay between 33 and 50% of their egg complement. During the third 24 h most flight activity occurs. Smaller, artificially starved females are much more active, especially during the second 24-h period, when many fly before ovipositing. Timing of oviposition and flight is under photoperiodic control: female flight occurs just before dark after peak oviposition while male activity starts before dark, but peaks after dark, with a morning peak of variable intensity.

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.

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.

(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.

Window flight traps baited with ethanol attracted 15 genera representing 25 species of scolytids. Monarthrum fasciatum and Xyleborus saxeseni were the most frequently trapped scolytids. Evidence for seasonal flight periods and vertical flight distribution are presented for Hypothenemus dissimilis, X. ferrugineus, X. saxeseni, X. sayi, X. xylographus, M. fasciatum, M. mali, and Corthylus columbianus. Live Q. velutina injected with ethanol attracted five species of scolytids: X. saxeseni, X. xylographus, M. fasciatum, M. mali, and C. columbianus.

A field trial with toxic-bait blocks for suppression of subterranean termite activity was initiated in Toronto. Decayed, mirex-impregnated red pine wood blocks 2.5 × 3.8 × 0.5 cm were placed individually in soil at 1.5-m intervals. Attack on bait blocks effectively suppressed termite activity for 3 years in the eight plots. The method offers a cheaper, environmentally sound, effective alternative to conventional soil-poisoning methods.

Euxoa melana n. sp., a sibling species of E. misturata (Smith), is described from the Panhandle area of Texas and from south-western Kansas. Together, the two species are herein referred to as the misturata group which is defined on the basis of genitalic characters. Adults and genitalia are illustrated.

Late-stage gypsy moth larvae, Porthetria dispar (L.), orient by polarized light in woodland openings. Activity of larvae was greatest before 1030 h and after 1400 h Eastern Standard Time, when plane-polarized sky-light was stronger and ground surface temperatures more moderate than during midday. Larvae in the opening were attracted to vertical objects up to 3 m distant at cardinal points closest to their path of orientation but much less to the cardinal points furthest away. Most larvae move in a north to northeast or south to southwest direction at abroad angle to the direction of the sun’s rays.

The synthetic plant growth regulator indolebutyric acid delayed pupation, produced lighter pupae, and interfered with the larva-to-pupa molt of the western tent caterpillar, Malacosoma californicum pluviale (Dyar), when it was mixed with water (0.1 g/1.) in which cut foliage for rearing the larvae was kept. Treatment of very young larvae led to adults that produced more and better eggs than the controls. Treating older larvae produced antigonadotrophic effects.

An investigation was made of the impact of a series of environmental catastrophes upon herbivore population regulation through density-dependent genetic feedback interactions with simulated plants. Mean density and amplitude of fluctuation of the herbivore in the control system (only susceptible alleles in the plant population) were higher than in the genetic feedback system (3 resistant alleles and 3 susceptible alleles in the plant population). Mean density and amplitude of fluctuation of the herbivores in the catastrophic system (only susceptible alleles in the plant population and the herbivore population subject to a series of environmental catastrophes) were lower than in the control and genetic feedback systems, but both mean density and amplitude of fluctuation were higher than in the genetic feedback and catastrophic system (3 resistant and 3 susceptible alleles in the plant population and the herbivore population subject to a series of environmental catastrophes). The results of this experiment suggest that genetic feedback can exert a controlling influence in population dynamics even in systems where environmental catastrophes are a common occurrence.