A study of the cast-off head capsules of fourth-instar larvae of Deilinia variolaria (Guenée), D. borealis Hulst, D. exanthemata bryantaria Taylor, D. erythemaria (Guenée), Drepanulatrix unicalcararia (Guenée), D. foeminaria (Guenée), and D. falcataria (Packard) shows considerable variation in colour pattern. The colour pattern varies sufficiently between species and yet is constant enough within species to enable one to construct a key to their identity. This key is very useful in identification where the larva has been parasitized.

Pseudaletia unipuncta (Haworth) was reared at eight constant temperatures from 5° to 31 °C. The eggs hatched at all temperatures except 5 °C. Development was completed at 13°, 17°, 21°, 25°, and 29 °C but at 10° and 31 °C none survived beyond the final larval instar.The duration of each stage decreased with rise in temperature up to 29 °C; but a further rise brought no further change, or even an increase. Developmental rates plotted against temperature gave shallow sigmoid curves with the maximum development rate near 29 °C for all stages except for the final instar larva where it was between 25° and 29 °C. Various alternating temperature regimes had no special influence on the rate of the development of eggs or larvae.There was a significant linear increase in larval head width with rise in temperature for all instars except the first. For larvae with six instars, the mean head width in the last instar ranged from 3.15 mm at 13 °C to 3.38 mm at 29 °C. At 13 °C some larvae required an additional moult to reach the apparent minimum size (about 3 mm) to complete development.

The Nearctic species of the genus Atrometus Foerster (Hymenoptera: Ichneumonidae) north of Mexico are revised. Three previously recognized Nearctic species, A. praediscae, A. clavipes, and A. evetrivorus, are synonymized with A. geniculatus Holmgren from the Palearctic Region. A new species A. badius and a new subspecies A. geniculatus obscurus are described. A key is presented for the separation of the species and subspecies.

A non-diapause strain of the migratory grasshopper, Melanoplus sanguinipes (Fabr.), has been developed over the past 12 years by selecting for rearing those grasshoppers that hatched from eggs not previously cooled. Because this strain can be reproduced at the rate of six to seven generations per year it is proving to be a useful experimental animal.

New hosts of an introduced Oriental ambrosia beetle were tupelo (Nyssa aquatica), swamp cypress (Taxodium distichum), and black cherry (Prunus serotina). Known distribution was extended southward into North Carolina. A partial seasonal development with simple through complex gallery systems was observed.

The odor produced by male Ips grandicollis attacking caged loblolly pine bolts was not very effective in attracting marked beetles. Only 2.4% of the 9,417 beetles released around the attracting attacks were recaptured.Unscreened infested bolts lost their attractiveness to responding beetles when about 27 attacks per square foot of bark surface had been reached. More beetles attacked bolts placed outside of a beetle producing area than those within. The latter indicates that a dispersal flight may be needed before response takes place.

Midilambia n. gen. is described for Cacographis colombiana Schaus. A lectotype is designated for the species, which is transferred from Midilinae to Nymphulinae.

Paired mandibular mycangia are present in both sexes of the bark beetle Dryocoetes confusus Sw. These fungus repositories were not found in either sex of another bark beetle of the same genus, Dryocoetes affaber Mann.

The range of the face fly, Musca autumnalis De Geer, has extended from the site of its first North American occurrence in Nova Scotia in 1952 to the northern half of the United States from coast to coast and every province in Canada. The first recorded appearance in Western Canada was at Virden, Man., in 1964 and it has since become established in eastern Saskatchewan. Face flies moved from Washington and Idaho into British Columbia in 1966. In 1967 they spread to most areas of the southern half of British Columbia and into southwestern Alberta through the Crowsnest Pass. Moisture and shade in pastures influenced the numbers of face flies seen on cattle and resulted in higher numbers than under dry prairie conditions.

The onitis group of the ichneumonid genus Trieces in the Nearctic region is revised to include redefinitions of the three previously described species, onitis (Davis), arcuatus Townes and Townes, and diffidens Townes and Townes, plus descriptions of six new species. A key to species, and illustrations are provided. Host data are given for six species, all of which are parasites of deciduous forest Lepidoptera in Canada.

Newly emerged adults of Dendroctonus pseudotsugae Hopkins were separated into pairs of similar size. One beetle from each pair was used as a control; the other was flown on a rotating mill. Soxhlet extractions in petroleum ether revealed that the flown beetles contained significantly less fat.

Megachile rotundata (F.) is a domesticated bee used to pollinate alfalfa in southern Alberta. There it may have four species of parasites, all chalcidoids. These parasites are removable by water traps before the hives are set in the field. Three of these parasites, Monodontomerus obscurus Westw., Dibrachys maculipennis Sz., and Pteromalus venustus Wlkr,, are European in origin. The first seems not to be established in Canada; the latter two have been reared from Canadian species of Megachile and thereby may prove a source of parasitism. The fourth species, Melittobia chalybii Ashm., is a widespread, nearctic, multivoltine species and is known as a laboratory pest of hymenopterous nests; it is likely to be the major parasite in rotundata nests. A key is given for the parasitic species.

The unique habits of a jack pine needle-miner, Eucordylea canusella (Free.), are described. It feeds for the greater part of its life on dead or dying needle tissue and on the fungus Aureobasidium pullulans de Bary (Arnaud), which grows within the needle-pair following construction of a mine by the first-instar larva. On reaching maturity, the larvae revert to a more conventional needle-mining behaviour. This habit is unusual in defoliating Lepidoptera although other species in the same, or closely related genera, are also thought to feed upon fungi. The impact of these findings on the taxonomy of Eucordylea spp. is discussed.

The oviposition behavior of the pteromalid parasitoid Nasonia vitripennis (Walker) was investigated in an attempt to explain the difference in population density maintained on two species of host, the housefly, Musca domestica L., and the blowfly, Phaenicia sericata (Meigen). The behavior of a female wasp was significantly affected by the species of host to which she was exposed. When presented with 10 pupae for 24 hours she averaged 14.2 eggs on 3.0 housefly hosts and 8.3 eggs on 7.2 blowfly hosts of the same size.The importance of the alteration in behavior to the population density of Nasonia became apparent when the suitability of the two host species was examined. At all densities of eggs more wasps matured on blowfly pupae than on housefly pupae of the same size. Survival on both hosts decreased as the density of Nasonia eggs increased. The difference in egg distribution, coupled with lower survival on housefly pupae and at increased density suggests a considerably lower production by this parasitoid on housefly hosts, compared with that on blowfly pupae.

A method is described for mass-rearing Chrysocharis laricinellae (Ratzeburg) on larch casebearer larvae, employing a water culture system for tamarack. The rearing unit accommodates a well-defined episode (limited contact) in the interaction with its host. The yield is about 100 healthy parasites obtained from 300 cases, when the initial inoculum was 15 parasite females.

Four species are recognized in the genus Holcopsis Enderlein: bifenestrata (Osten Sacken 1886), fenestrata Enderlein 1923, bequaerti (Philip 1943) and pilifera (Philip 1943). All specimens for which the locality is known are from the State of Durango, Mexico. The genus is characterized and its possible relationship with Bolbodimyia Bigot is indicated. Collection data for all known specimens are given. The species are characterized by the use of a descriptive key. The wing, third antennal segment, and second palpal segment of the female of each species is illustrated.