Nuisance species of riverine insects were temporarily eliminated from the Expo 67 site at Montreal in 1967 by four applications of an emulsifiable formulation of DDD (TDE) to the St. Lawrence River, one in each of the months of May, June, July, and August of 1967. In each treatment sufficient DDD was applied 1.5 miles above the infested rapids to provide a concentration of about 0.4 p.p.m. of DDD in the water, throughout a period of about 15 minutes. Each treatment caused the immediate detachment of about 98% of the Trichoptera larvae (mainly Hydropsychidae), and lesser percentages of other aquatic arthropods. No observable effects on fish were detected. Populations of arthropods, especially amphipods, rapidly restored themselves after each treatment. During August 1967, both amphipods and gastropods were more abundant in treated than in untreated rapids. Residues of DDD were negligible and were expected to be relatively non-persistent. Occasional swarms of Trichoptera of relatively minor proportions, detected at the Expo 67 site by light traps, presumably arrived on steady southerly winds from the untreated Lachine Rapids more than 7 miles upriver. Information about the decomposition of DDD and related chlorinated hydrocarbons in nature is reviewed.

Tobacco budworms, Heliothis virescens (F.), with inherited sterility caused by irradiation of the male parent were smaller than progeny from normal parents and developed more slowly throughout the larval and pupal periods. In the second generation the population segregated into two groups, those with normal and those with delayed development. Also, when the P1 male received 15.0 krad, 8% of the F1 larvae had more than the normal five instars. Moreover, when those F1 progeny that had only five larval instars were outcrossed to normal moths, this tendency for supernumerary molts increased nearly 3-fold. The slower development of progeny of treated moths would have to be considered in field tests made to evaluate the effect of inherited sterility on the tobacco budworm. However, with continuous release of irradiated males, the delayed development or smaller size of the progeny should not lessen the possibility that this method could successfully suppress field populations.

Forty-nine 0.1 m2 emergence traps positioned over several substrate types and a range of water depths 0.9 to 5.5 m, from 2 June to 7 September 1967, collected 979 caddisflies and 195 mayflies. The caddisfly emergence was restricted to the period 24 June −27 August, and mayfly emergence to the period 2–30 July.The sex ratio for the caddisflies showed, in almost every case, a preponderance of females and no male Neureclipsis bimaculatus (Linn.) and N. validus Walk, were collected. Most of the caddisflies showed preference for a particular depth and/or substrate type. The few caddisflies which were present both in large numbers and distributed over a fairly wide depth range indicated that there is a relationship between depth distribution (temperature) and emergence time, heat perhaps being involved both in control of rate of maturation and as a releasing agent for the actual emergence.Male Stenonema interpunctatum canadense (Walker) showed peak emergence about 5 days before the females and also outnumbered the females by about 3:1. No relationship seemed to exist between depth distribution and emergence time for any of the mayfly species. However, the emergence of one species, Caenis forcipata (McD.) may be related to weather conditions.

Almost 40% of the cells of Megachile rotundata (F.) from the earliest completed tunnels in the hives produced as second-generation bees. This percentage rapidly decreased in the later completed tunnels. The difference between wing venation of bees that emerged in spring and of second-generation bees that emerged in summer appears to be related to voltinism.

Adult Trichoptera of 39 species representing 11 families were collected from 4 emergence traps in Oak Creek, Corvallis, Ore., between May 1968 and December 1970. Glossosomatidae and Limnephilidae were the most abundant families, but Rhyacophilidae was represented by the most species. Relative abundance, seasonal occurrence, sex ratios, and ecological segregation of related species are discussed.

Neosistentes reared from eggs of the final generation of the year only developed under a regime of fluctuating temperature. Progeny of the first generation the following spring developed under both constant and fluctuating temperature. In addition, the latter group displayed developmental variability that might provide a basis from which distinct ecological races could develop. Those individuals that developed rapidly showed little variability in the time required to complete development. On the other hand, those that developed slowly displayed more variability. There was no evidence of two distinct developmental groups among individuals reared under a regime of temperature cycling between 55°F and 75°F as the entire group developed rapidly; this treatment also produced the lowest mortality.

Females of Spalangia cameroni Perk, use the ovipositor to differentiate between unparasitized and parasitized housefly (Musca domestica L.) pupae; and prefer to lay on unparasitized hosts instead of those attacked by S. cameroni, Nasonia vitripennis (Walk.), or Muscidifurax zaraptor K. & L. (Hymenoptera: Pteromalidae). The intensities of oviposition restraint on the three kinds of attacked hosts are similar. Changes in parasitized pupae to which the female parasites react probably involve "venoms" injected by each species during oviposition.

Differences in weevil attack between trees containing crystallizing and non-crystallizing resin were observed. Among twenty non-crystallizers only three trees were successfully attacked by the white-pine weevil. About 50% of the remaining population was successfully attacked. Resin crystallization can thus be used as a characteristic to screen for resistance to the white-pine weevil.Since several other characteristics such as leader diameter, depth of cortical resin ducts and bark thickness are also related to weevil resistance, a discriminant function could be developed to maximize discrimination between susceptible and resistant trees by a properly weighted combination of characteristics related to weevil resistance.

Male Heliothis virescens (F.) were irradiated with 7.5, 15.0, or 22.5 krad of 7-rays and crossed with untreated females. Then fertility of these treated males (PJ and of their descendants was studied for two generations. In addition, the postembryonic survival of the Fx and F2 generations was studied. Fertility (percentage egg hatch) of P1 males was greater than that of Ft males or Fj females. There was more postembryonic survival in the F1 than in the F2 generation. When the Px males received 22.5 krad, few F2 larvae hatched, and none survived. When Pt males received 15.0 krad, the fertility of F1 males and females was less than 5, and 10%, respectively, and less than 20% of the F2 larvae survived; however, sterility factors were nearly eliminated by the third generation. When P1 males received 7.5 or 15.0 krad, the average fertility of F2 males was greater than that of F1 or P1 males but less than that of untreated controls, though fertility of some F2 males was normal. The lower the dose received by P1 males, the greater was the frequency of F2 males with normal fertility.

The rate of ingestion by Podisus maculiventris Say feeding on larvae of Tenebrio molitor L. or Galleria mellonella L. is almost constant with time and from one predator to another. The rate is 1.80 ±.070 mg/hr/individual.No effect of the age or size of the predator nor of the species of prey on the feeding rate could be detected. Different periods of starvation before feeding directly affect the percentage of individuals that feed, but not the actual rate of feeding, until 60 hours of starvation. After 72 hours starvation, there is a drop in the feeding rate which we attribute, tentatively, to a weakening of the feeding mechanism by the starvation.The initial weight of the larva used as prey affects the rate of sucking during the first hour or two of each period of feeding and this relationship is responsible for a slight non-linearity in the individual curves of feeding. This may be an effect of the internal pressure of the body fluids in the prey.The process of ingestion is reviewed and compared with published studies of other species of Hemiptera. It is suggested that after insertion of the stylets of the predator into the body of the prey, the feeding process is affected by the internal pressure of the prey during the early part of a period of feeding but that, thereafter, the sucking action is maintained constant by the action of capillarity and the pharyngeal pump.

An eriophyoid mite, Nalepella halourga Keifer, is newly recorded in Canada from two hosts: black spruce, Picea mariana (Mill.) BSP., from Ontario, and Norway spruce, Picea abies (L.) Karst., from New Brunswick. For the first time this mite is reported as damaging black spruce under greenhouse conditions. A key to the eight described species of Nalepella and notes on their host associations and economic importance are included.

Colonies of Formica obscuripes Forel and Dolichoderus taschenbergi (Mayr), two of the most common and widespread species of predacious ants in jack pine stands of the Sandilands Provincial Forest of southeastern Manitoba, were transplanted to new locations in three young jack pine plantations. When nests of the two species were alternated and spaced at intervals of 20 m, little migration occurred; a spacing of 5 m resulted in excessive movement subsequent to the transplant.

The seasonal occurrence and larval habits of Dioryctria banksiella Mutuura, Munroe, and Ross in the western gall rust Endocronartium harknessii (J. P. Moore) Y. Hiratsuka of jack pine, Pinus banksiana Lamb., were studied in Manitoba and Saskatchewan. The early instars score the gall tissue below the bark, and the later instars mine the gall tissue and heartwood. The insect overwinters in the larval stage. The last-instar larvae pupate partly exposed and not entirely within the rust gall from June to July and adults emerge from July to August. The six species of parasites recovered from D. banksiella were Bracon lutus Provancher, Bracon sp., Microchelonus sp., Agathis binominata Muesebeck, Exeristes comstockii (Cresson), and Stiboscopus n. sp. Morphological characters used in separating the last-instar larvae and pupae of D. banksiella from those of other known species of Dioryctria are given.

Adult apple maggots, Rhagoletis pomonella (Walsh), were relatively free from attacks by predators in southern Ontario. The main reason for this was the flies’ alert avoidance of approaching objects. In addition to this protection from predators, the flies appeared to be avoided by hunting spiders. Adults of the cherry fruit fly, Rhagoletis cinqulata (Loew), were equally alert and apparently free from predation while they were in apple trees.

Parasitoid populations were sampled before, and for 4 years following, an aerial application of the insecticide phosphamidon to control a sawfly outbreak. Adult parasitoid mortality was high because of spraying, but a reservoir of parasitoids in host cocoons remained to repopulate the treated areas. In moister sites the number of species decreased and their relative abundance changed, but moderate numbers of parasitoids remained 4 years after spraying. In a dry site with little ground vegetation, none of the species present before spraying remained by the fourth year.

Male apple maggot flies, Rhagoletis pomonella (Walsh), were present on ceresin wax domes (the site of oviposition and the site of assembly for mating) in much greater relative frequency when caged with 1 or more females or with several other males than when caged alone. Field and laboratory experiments subsequently revealed that a principal stimulus eliciting this greater degree of male assembly was an unidentified chemical(s) deposited on the surface of apples and ceresin domes by both sexes (but in greater amount by mature females) causing arriving males to spend up to twice as much time there as on untreated fruit. The presence of the chemical did not elicit any greater attraction of males to the fruit. The consequence of the longer male residency on domes with the chemical was male aggregation and an ensuant higher frequency of mutual encounter and attempted copulation than on untreated domes. While the chemical acts to arrest males, we theorize that mere detection of its presence may be sufficient to cause males to remain in the vicinity and watch for females.

Diapause in Hippodamia tredecimpunctata (Linnaeus) can be inhibited by exposing adult females to photoperiod regimens of LD 16:8 or 14:10 hours. Exposing adult females to a photoperiod of LD 12:12 hours initiates diapause. The photoperiod to which the egg, larval, and pupal stages are exposed has no effect on the developmental rate and has little effect on adult diapause status.