The relationship between the density of insect holes in the bark (X1) and the density of emerged mountain pine beetles (Y) was investigated in naturally infested lodgepole pine in south-central British Columbia. The density of exit and ventilation holes (Ho) that were present in the bark prior to emergence by mountain pine beetle averaged 10% of all holes present following the emergence period. There was a weak but significant inverse relationship between Ho and both phloem thickness and density of emerged mountain pine beetles. Painting the bark with light-color latex paint did not affect survival or the temporal pattern of emergence by mountain pine beetle but ensured identification and greatly enhanced counting of fresh exit holes. Of the several regression models investigated, the relation between Y and both X1 and X2 (= X1 – Ho) was best fitted by a log-log linear model. A method is suggested for setting limits on the size of exit holes cut by mountain pine beetle in order to exclude from X2 much of the variation caused by exit holes cut by associated insects. A simple mathematical model was developed of the relationship between mean density of exit holes and the density of emerged mountain pine beetles.

Nine species of Epidamaeus of subarctic western North America and extreme northeastern USSR are discussed. Six new species, Epidamaeus aborigensis, E. chukchi, E. floccosus, E. gilyarovi, E. koyukon and E. nasutus, are proposed; E. gibbofemoratus, E. hastatus and E. tenuissimus, previously described by Hammer, are redescribed.

Four aggregation sites for male Cephenemyia trompe Modeer were studied in the Kluane Game Sanctuary, southwest Yukon. All sites were well-defined topographical peaks at considerable distances (usually greater than 1 km) from one another. Males rested on the rocks and vegetation and individuals made frequent flights to investigate passing insects, presumably in search of a female. Male flies were active at the sites on element days; activity was a function of both temperature and light intensity. Flies remained at a particular site at least throughout the day but did not defend individual territories.

Cypermethrin was more toxic to adults of the tarnished plant bug, Lygus lineolaris Palisot de Beauvois, in both laboratory and field studies, than other synthetic pyrethroid, organophosphorus, or chlorinated-hydrocarbon insecticides. The synthetic pyrethroids were more toxic than other groups of insecticides. Residues of cypermethrin were toxic to plant bugs for 7–10 days; other compounds were effective for shorter periods. In the field 1 application of cypermethrin effectively controlled tarnished plant bugs on peach.

The insect parasite Cotesia rubecula (Marshall) shows a long-day, photoperiodic response that results in diapause in the eonymph. Within the region of the critical photoperiod, the diapause response is modified by temperature and by the duration of the developmental period of the larval parasite, but in field populations in Vancouver, diapause is predominantly a response to short photoperiods. There is evidence that the parasite's response is largely independent of the host's response. Once diapause is induced, there is an obligatory dormant period of at least 2 months after which diapause terminates when specific-heat requirements are fulfilled. The estimated heat requirements are used to predict the date of diapause termination and the emergence of parasite adults in the field. Parasite activity begins almost 6 weeks after that of its host.

The critical photoperiod for populations in Vancouver, Canada, lies between 15- and 16-h photophase but in Canberra, Australia, the critical photoperiod is less than 13 h. The significance of this difference in the diapause response of the 2 introduced populations is discussed and recommendations are made for further biocontrol efforts.

Film records of cutworms feeding on cabbage showed that in sampling and continuous feeding, the mandibles, maxillary palps, galeae, labial palps, and labrum contacted the leaf. Sampling involves palpation with the maxillary palps; this is followed by test biting, during which the galeae, labrum, and labial palps make initial contact with the plant. Test biting may be followed by continuous feeding in which all of the mouthparts contact the leaf in characteristic patterns. The actions of the mouthparts are discussed in relation to the function of their chemosensilla.

Fenusa pusilla (Lepeletier) and Messa nana Klug coexist on white birch near Sudbury, ON. Both species often oviposit simultaneously, but their mines are spatially separated because of differences in ovipositional behavior. Most first-generation F. pusilla oviposit in unfolding leaves arising from currently expanding shoots situated distally on the branch, whereas M. nana oviposits in fully expanded leaves arising from older shoots situated proximally on the branch. Leaf tissues damaged by oviposition and larval feeding were examined. Larvae of F. pusilla consume both palisade and spongy mesophyll, whereas larvae of M. nana consume only palisade. It is suggested that F. pusilla develops faster than M. nana because it feeds on leaves of greater nutritional value and digests more cellular components.

Unlike some tortricids that are refractory to diflubenzuron, the oak-leaf shredder, Croesia semipurpurana (Kearfott), is susceptible to this molt-inhibiting insect growth regulator. Aerial application of 140 g in 4.7 L/ha provides good control of this insect and affords foliage protection. The success of diflubenzuron was evaluated by sampling larvae and pupae. Monitoring male moths with pheromone traps provided corroborative evidence of a significant decrease in the post-treatment population. The successful assessment by pheromone monitoring here merits its consideration for other control operations in forestry.

The braconid Pholetesor (= Apanteles) ornigis (Weed) was the major parasite of the spotted tentiform leafminer, Phyllonorycter blancardella (Fabr.), at 21 sites, in 9 counties in southern Ontario. The eulophids Sympiesis sericeicornis (Nees) (12 sites, 6 counties), S. dolichogaster Ashmead (9 sites, 5 counties), S. marylandensis Girault (8 sites, 6 counties) and Pnigalio maculipes (Crawford) (6 sites, 5 counties) were the major chalcidoids recovered. Other species recovered were 10 eulophids, 2 pteromalids, and 2 ichneumonids. The major hyperparasite of P. ornigis was S. sericeicornis, but S. dolichogaster, Habrocytus sp., Catolaccus sp., Gelis sp., and Hypopteromalus sp. were also recovered.

Mean weekly catch of adult Psila rosae (F.) on sticky, yellow-painted cardboard traps from 93 commercial carrot fields provided seasonal records of their activity during 1980–1983 in the lower Fraser Valley, British Columbia. When monitoring extended from April through November in 1982 and 1983, 3 distinct periods of adult activity were observed that probably reflect the occurrence of 3 adult generations per year. Trap catch first peaked in mid- to late-May, followed by a second peak in late-July to early-August, and a third peak in mid-October. Of the temperature summations calculated, those commencing 1 February provided the most accurate degree-day (DD) indices for predicting seasonal activity of overwintering and 1st-generation adults. Four-year means for cumulative DD above 3 °C (air temperature) after 1 February for first, 10%, maximum, and 90% trap catch of the overwintering generation were 326, 435, 557, and 838 DD, respectively.

The production of excess males in thelytokous Muscidifurax uniraptor Kogan & Legner was triggered by high temperature (32.2 °C) during oviposition, and may result from a blockage of endomitosis in the egg. A minimum oviposition period of 24 h at 25 °C prior to continuous high temperature was an important prerequisite. A few receptive oocytes may be present before oviposition, with new ones formed during the first 24 h of the oviposition period at 25 °C. Although heat treatment must begin during a relatively short receptive period ("window of susceptibility") early in adult life, it has to persist longer than 24 h at low oviposition rates (20 hosts/day) and < 24 h at high oviposition rates (50 hosts/day) to block effectively endomitosis and the formation of diploid, female-producing eggs.

The disruption of chemical communication between adult insects by the use of synthetic sex pheromones is an attractive method of insect control. However the mechanism of disruption is not clearly understood. It is generally considered that 3 mechanisms are in operation (see review by Bartell 1982): masking of the natural-pheromone plumes by permeation of the atmosphere with synthetic pheromone; orientation of males to false trails; and habituation of the central nervous system by prolonged or repeated exposure to the pheromone. The relative importance of these 3 mechanisms in disruption is of concern, as this can affect the strategy for disseminating the pheromone.