The following 14 aphids are known to feed on species of Solidago in Canada: Cachryphora serotinae (Oestlund), Dactynotus caligatus Richards, Dactynotus canadensis new species, Dactynotus erigeronensis (Thomas), Dactynotus gravicornis (Patch), Dactynotus lanceolatus (Patch), Dactynotus macgillivrayae Olive, Dactynotus nigrotibius Olive, Dactynotus nigotuberculatus Olive, Dactynotus pieloui new species, Dactynotus pseudochrysanthemi Olive, Dactynotus tissoti Boudreaux, Dactynotus solirostratus new species, and Macrosiphum goldamaryae (Knowlton). A key and a list of associated host plants are given.

The two subgenera and 20 species of the crab spider genus Ebo in North America north of Mexico are described or redescribed, keyed, and illustrated. The subgenus Ebo contains seven species, of which E. iviei, E. evansae, E. contrasts, and E. punctatus are described as new and the female of E. merkeli Schick is described for the first time. The subgenus Titanebo contains 13 species, of which E. cantralli is described as new and the female of E. texanus is described for the first time.

Experiments were carried out to determine the functional response of Podisus modestus (Dallas) to densities of two colonial species of jack pine sawfly, Neodiprion swainei (Middleton) and N. pratti banksianae (Rohwer). Two types of functional response curve were exhibited by the pentatomids, a domed response curve and a negatively accelerated curve.The domed response was caused by the more effective defense reactions of the sawfly larvae at higher densities.An equation is proposed for the domed response curve. The implications of the domed functional response are discussed in relation to the social behavior of these sawflies.

The taxonomic framework of the lepidopterous family Sphingidae established by Rothschild and Jordan (1903) contains many anomalies. Indeed, it has been suggested that as the taxonomic lines run across both larval and host-plant groupings, the family should be totally rearranged. In this paper the host plants of the Semanophorinae (one subfamily of the Sphingidae) are examined and discussed. On the basis of host plants, five groups of sphingids, which appear to be taxonomic entities, are distinguished. The identification of the host-plant groups is also a preliminary to the use of Celerio euphorbiae (L.) for the biological control of weedy Euphorbia spp. in Canada.

Terrestrial arthropods collected from Bathurst Island in 1969 are listed: 78 species (4 spiders, 13 mites, and 61 insects, 30 of which are chironomids) have now been collected in this area of the high arctic. Notes on the overwintering of some of the commoner insect species are given. Although the collecting season was a poor one in 1969 because of adverse weather conditions, the list probably represents half or more of the island’s arthropod fauna. The nature of the list indicates that this fauna is impoverished compared to some other areas of the Queen Elizabeth Islands. This impoverishment may be largely explained by climatic factors.

Small numbers (147–388) of Olesicampe benefactor Hinz, a European ichneumonid parasite of the larch sawfly, Pristiphora erichsonii (Htg.), were released in Maine, Nova Scotia, and New Brunswick in 1967. The parasite became established and has survived through two winters at five release points, and three winters on three release sites; on two sites the continued survival of the parasites is unconfirmed because of the collapse of the host population. O. benefactor is known to disperse slowly and even if it is successful in controlling the sawfly in the release areas, control over large areas may require releases at many locations.The subject of the range of host densities at which parasite releases should be made to ensure the greatest parasite production per parasite released, and hence the greatest chance of successful establishment, is discussed.

Comparatively few laboratory-caged apple maggot flies, Rhagoletis pomonella (Walsh), of either sex arrived at the site of assembly for mating (ceresin wax oviposition domes) and no mating pair or ovipositing females were observed until the flies were 7–8 days old. From then on, the level of all three of these activities progressively increased.With respect to the time of day of activity, in the field, assembly of both sexes of flies on the fruit, mating, and oviposition all occurred predominantly during the afternoon on a day when the sun shone brightly throughout the 15-hr daylight period and the ambient temperature was 16 °C at dawn, 24.8° in mid-afternoon, and 17.5° at dusk. Little or no activities of these sorts occurred before mid-morning and toward dusk. In the laboratory, where light intensity was constant at 1000 lux during the 15-hr photophase, the temporal pattern of these activities was the same as in the field when laboratory temperature was programmed to be the same as in the field for the corresponding hour of daylight. However, when laboratory temperature was programmed to be constant at 24.8°, these activities occurred at a high rate throughout the photophase. None of these activities was observed to have been initiated in darkness. It is concluded that sexually mature apple maggot flies may assemble on the fruit, mate, and oviposit whenever temperature is favorable and light intensity is sufficient to permit adequate vision.

The apple aphid was reared on 1-year-old trees in a controlled environment cabinet with simulated mid-June through October 1968 daylengths and temperatures. Maximum rates of increase (ca. 2.7-fold per week) were observed during the first 5 weeks of the experiment and maximum populations were obtained in 7 weeks at the time the trees stopped growth when the diel photoperiod was 14.8 hr, and light/dark temperature was 20.5°/15.5 °C. The ratio of nymphs to adults increased from 5:1 to 10:1 from week 2 to week 8, followed by a rapid decline. At week 12 there were more adults than nymphs and the nymph:adult ratio remained 1:3 through the remainder of the experiment. Alate aphids appeared 2 weeks following infestation, increased very rapidly, ca. 6-fold per week, and maximum abundance was noted at the end of 6 weeks. Their numbers declined nearly as rapidly at ca. 0.35-fold per week and they were not seen after week 11. As the numbers of alate aphids decreased, apterous adults increased to week 12, remained constant to week 15, and slowly decreased in an environment of shorter daylengths and lower temperatures. The rate of apterous adult aphid increase was similar to the rate of accumulated degree days during the first 8 weeks and again in the 10- to 15-week period.Aphids were concentrated on the tree tops during the first 6 weeks of the experiment. A gradual migration followed and the aphids became dispersed over the trees with minor concentrations near the centers of the trees.

The influence of constant temperatures on the non-diapause development of Hyssopus thymus was studied and the results of these studies are presented. A lower threshold for development of less than 12 °C and an upper threshold of about 32 °C were determined. Mean times for and rates of development at different temperatures are presented for all developmental stages. The egg is the stage most sensitive to temperature change. Regression equations describing the relationship between the rate of development and temperature for these stages are given and a thermal constant (K) of about 190 degree-days is calculated for total development. This constant is not applicable to naturally fluctuating temperatures. The results of these studies are discussed in relation to the potential impact of H. thymus on European pine shoot moth dynamics under different climatic conditions. It is concluded that H. thymus should be more effective in warmer seasons and at lower latitudes.

Coenopoeus palmeri (LeConte) feeds on the several species of staghorn cacti of the United States. The adults feed externally at night and the larvae mine internally. Adults are active in spring and summer. The larvae feed through the summer and fall and pupate within the larval mine the following spring. The genitalia of both sexes are illustrated and the larva and pupa described.

A synthesis of observations on density-dependent interactions in parasitoid populations is attempted, working from the particular aspects of discrimination against parasitized hosts and detailed observations on parasitoid behavior, to more general aspects of parasitoid ecology, dispersal, distribution, and response to host populations. Females of Pleolophus basizonus (Gravenhorst) are able to discriminate against parasitized hosts of Neodiprion swainei Middleton between narrow limits (mean densities of 0.4 to 1.4 eggs per cocoon) set by the probability of a female finding an unparasitized host. They show mutual interference in egg laying at high parasitoid:host ratios, and a density-dependent escape reaction to adult parasitoid density. These behaviors all result from the recognition of repellent trail odors left by searching females. Response of individual females to high parasitoid densities may therefore lead to dispersal, the occupation by the population of more, but not so favorable habitats, and an apparent density-independent response to host populations.

Tenebrio molitor L. eggs in 15 age groups ranging from 0.5 to 7.5 days were irradiated with 10 dosages of gamma radiation ranging from 0.5 to 160 krad. The study showed that age had a pronounced effect on radiation-induced egg mortality. There was a 250-fold increase in resistance as eggs matured from 0.5 to 7.5 days as measured by the dosage required to produce an LD50.