The valval shapes of 314 male Nearctic Limenitis (including 15 samples from nine localities and 20 laboratory-bred hybrids) were examined for anatomical differences. Seven phenotypically different forms are included as follows: L. arthemis, astyanax, the intergrade form proserpina, L. archippus, the rare hybrid form arthechippus, L. lorquini, and L. weidemeyerii. The claspers of each specimen were dissected, mounted on slides, and photographed. Counts and measurements were made of eight larval characters (including four apical features: the number of distal teeth, distal width, and dorsal and ventral angles, as well as four basal traits: valval length and base, and the length and basal width of the inner process), and right forewing length. The data were compared between and among samples by canonical analysis and by one-way analysis of variance tests. Forms of the arthemis–astyanax complex possess no obvious morphological differences in their valvae. The apical characters are constant throughout the group, although the basal valval traits and forewing length show variation in size which is inversely correlated with latitude. The similarity of valval structure in these forms is evidence that they are conspecific. Consistent differences in the apical shapes and valval characters of arthemis, archippus, lorquini, and weidemeyerii confirm that they represent valid species. The valvae of the hybrid form arthechippus are intermediate between the two parental types. The relationships of valval structure to hybridization and genetic isolation are discussed, and consideration is given to the probable evolutionary affinities of the common forms, and how they may have arisen.

Unmated female A. kühniella (Zell.) emitted a sex pheromone at the beginning of the light period of a 24 hour cycle of light and dark periods. There were no differences apparent in the duration of the calling posture by females in light of 1, 40, or 200 lux. A sex pheromone was extracted from the abdominal tips of unmated females of various ages with organic solvents, 3-day-old females gave the most potent extracts. Extracts of equal potence were obtained from females at different times during the diel cycles of photoperiod. The response of males to the extract was maximal at dawn, increased with age for 5 days, and was greater in light of 1 lux intensity than of 200 lux. Both sexes showed an anticipation of the beginning of the light period in their sexual behaviour, but if the timing of the cycle of photoperiod was changed the behaviour of both sexes became synchronised to the new cycle on its second or third occurrence.

An improved cage arrangement resulted in 73% of the female European pine shoot moths being mated during a 48-hour test. Key factors were continual airflow from females to males and a light-to-dark illumination change. The ponderosa pine tip moth, Rhyacionia zozana (Kearf.), the black-headed budworm, Acleris gloverana (Wlsm.), and two species of spruce budworm, Choristoneura occidentalis Freeman and C. viridis Freeman, were also tested in the apparatus with some success in every case.

The balsam woolly aphid was introduced over 60 years ago from Europe into the Maritime Provinces of Canada where it established on Abies balsamea (L.) Mill. Ecological characteristics of the insect that are important to the survival and spread of populations in the new environment are feeding habits, cold-hardiness, and dispersal capacity. The aphid feeds on the bark cortex of all parts of the tree from the stem to the crown. ’Stem attack’ refers to the population established on the main stem while ’twig attack’ refers to the population established in the crown where the aphid may settle on numerous sites but mainly at the base of young shoots. Freezing is fatal and the probability of freezing increases as temperatures fall below −5°F. There are no survivors at −35°F no matter how brief the exposure. The adults are wingless and populations are spread mainly through wind dispersal of crawlers and eggs.The climate of the Maritime Provinces changes markedly from the coast inland from maritime, through transitional, to continental. Infestations in maritime and continental climatic regions follow particular patterns while in the transitional region the course of infestation is irregular. Climate is unimportant in determining population trend in maritime climatic regions. The probability of experiencing temperatures below −15°F in a winter is 0.10 and populations survive on the stem and in the crown. Crown populations are dispersed freely and the aphid and aphid damage is general. In the continental climatic region, the probability of −30°F occurring in a winter is 0.46 and populations are restricted to the base of the tree where snow cover provides protection. Wind velocities below the canopy are light and infestations remain isolated and small with damage from stem attack accumulating at a slow rate. In the transitional climatic region, the severity of winter is irregular with periols of mild winters being broken by occasional extremely cold winters. Tree mortality from twig and stem attack has been heavy in some stands while infestations in adjacent and equally susceptible stands have been arrested by severe winters.

Poecilips pteridophytae Schedl is the first species of Scolytidae to be found on a fern. It appears to be fairly widely distributed in New Guinea on the tropical bracken fern, Pteridium aquilnum (L.). The association is most probably of recent evolutionary origin. The immature stages are described in the text. Its life history is relatively short, the life cycle raking 2 to 4 mouths, and takes place wholly width the stem of the fern, except for emigrating adults. P. pteridophytae may have considerable economic potential as a biological control agent of bracken fern in countries where it is a pest.

Pear psylla, Psylla pyricola Foerster, had three generations in 1968 in Nova Scotia. Laboratory studies indicated that overwintering females require mating in the spring to produce fertile eggs. The adults started activity by the end of March, Psylla eggs and nymphs were preyed on by eight predacious species in the laboratory. These and the larvae of another six predacious species were associated with psylla in the field. A few psylla nymphs were parasitized by Trechnites insidiosus (Crawford). Psylla adults fly or are carried with the prevailing winds and a significant percentage occur above the tops of the trees.

Utilizing the knowledge of their direct effects, the materials ryania, carbaryl, and Animert V-101 applied to a uniformly distributed population of the European red mite, Panonychus ulmi (Koch), altered the populations in plots in an apple orchard. Trends after treatment in both host mite and predator populations were assessed. Supplementary applications of the acaricides Animert V-101 or dicofol directed against certain generations of P. ulmi controlled outbreaks and altered the faunal levels during the following season. Ryania was largely innocuous to most species of predators with the exception of Atractotomus mali (Meyer) and Diaphnocoris spp., carbaryl was detrimental to most predacious species, and Animert V-101, while selectively toxic to phytophagous mites, was innocuous to all predacious insects and Typhlodromus pyri Scheuten.Phytophagous mite populations may be altered to almost prescribed levels with pesticides when the predator populations are known. This allows selective chemicals to be used to complement the predator effect and maintain red mites below the threshold of damage.

Agathis pumila (Ratzeburg) and Chrysocharis laricinellae (Ratzeburg) compete for their common host, the larch casebearer (Coleophora laricella (Hübner)). An analysis of the mechanism of this competition, based on a 2-year study at Joliette, Que., is presented. A. pumila, in sacrificing part of its own population, prevents a "one stage condition" and helps C. laricinellae build up to a point where the latter becomes host-regulative by massive attack. Competitive displacement of A. pumila by C. laricinellae is less frequent than expected because of the basically different ways in which the two parasite species spread, search for, select, and attack hosts. A. pumila may suffer about 50% loss from multiple parasitism, but apparently this does not affect its survival potential, its reproductive rate, and its ability to provide significant partial control of the larch casebearer.

The proportion of females of the European red mite, Panonychus ulmi (Koch), reared from periodic samples of larvae and nymphs from a peach orchard averaged about 75% with little seasonal variation. A male can copulate at least 11 times in 2 hr, and inseminate at least 26 females during its life span, but many later copulations inseminate the females incompletely or not at all. Some females copulate at least three times but one copulation with a young male enables a female to lay the usual proportion of fertilized (female) eggs, which exceeds that of unfertilized (male) eggs. No evidence of males with only one nymphal instar, as reported in Europe, was found in mites reared at 15°, 22°, or 30 °C. Males disperse much more rapidly than females.

Effects of temperature and resin on hatch of mountain pine beetle eggs were investigated. Per cent hatch was related to total degree-hours above 40°F, the average being 5113 for 50% hatch under field conditions. Average supercooling point was 1.3°F. Higher temperatures in the freezing range were lethal with long exposure. Atmosphere saturated with volatiles from liquid resin had very little effect on egg hatch, but direct contact with liquid resin greatly reduced egg hatch.

The apple aphid population density on 1-year-old trees under controlled conditions of decreasing temperatures and photoperiods equivalent to 1 August through 14 November 1967, remained almost static up to the time of apple tree defoliation. Alate forms disappeared and reproduction levelled off after a 13.3 hr, 17 °C light, and a 12 °C dark temperature were programmed. Aphids left the apex of the tree after vegetative growth ceased and became distributed more or less evenly over the older leaves. Egg deposition occurred after the photoperiod became shorter than 11.8/24 hr and temperatures less than 12 °C during the light period, 8 °C during darkness. This "autumn population" of aphids with no external detrimental biotic or extreme climatic effects produced winter eggs equal to one-third its numbers at the time of beginning oviposition.

The musculature of the prothorax and the prothoracic coxa of the adult male Choristoneura fumiferana (Clem.) is described in detail and is compared with three other families of the Lepidoptera.

All stages of the life cycle of the midge Tanytarsus (Paratanytarsus) dissimilis Joh. were subjected to low pH and the extremes of tolerance were determined. The life cycle could not be completed below a pH of 5.5