The fauna of the sporophores of the perennial bracket fungus Fomes fomentarius (L. ex Fr.) Kickx were examined in a 3-year study. One species of molluscs and more than 152 species of arthropods excluding mites, representing 13 orders, 70 families, and 5400 individuals, emerged from or were found on or in, 1448 sporophores detached from dead birch trees; the sporophores were collected each year in Gatineau Park, Que., kept individually in screen-topped glass jars in a laboratory, and examined for several months. Mites, which were recorded quantitatively only in the final year, added 4 orders, 19 families, and 30 species to the preceding totals. Mites were the most frequently occurring and probably the most numerous arthropods, followed by Coleoptera, Psocoptera, Collembola, Hymenoptera, and Diptera.The key organisms of the fauna were five species of beetles that were primarily responsible for tunnelling and destruction of the sporophores and would therefore exert great influence on the composition of the community. Their tunnels provided shelter and food for many smaller arthropods or facilitated their feeding. Some beetle species tunnelled the sporophores for one season and others, for several, but many living sporophores and most dead ones tunnelled by beetles were tunnelled in the same season by more than one species of beetles.There was considerable latitude in types of sporophores inhabited by various arthropods but some species were particularly attracted to living or dead, to younger or older, and to smaller or larger, sporophores. Some species were also attracted to certain regions of the sporophore more than were other species.Possible economic implications of observations made in the study are discussed.

Medetera aldrichii Wheeler larvae enter galleries of Dendroctonus ponderosae Hopkins through the beetle entrance holes. Observed larval densities of the fly were greatest in the May–June period following beetle attack. Densities were consistently greatest in the portion of the tree 5–10 ft aboveground; averaging around 3–4/sq. ft. The fly larvae probably cause a major share of the beetle mortality between August and the following May. The fly larvae pupate near beetle-created openings that lead from the galleries to the exterior.

A statewide survey was made in Florida to determine the resistance of house flies, Musca domestica L., from 25 different locations throughout the state to trichlorfon and dichlorvos in dry sugar baits. When compared with susceptible flies (Orlando regular strain), the resistance to trichlorfon ranged from 2.5- to 135.0-fold in flies from dairies and from 5.0- to 310.0-fold in flies from poultries. The resistance level to dichlorvos was 1.0- to 22.5-fold in those fly strains collected in dairies and 2.3- to 16.6-fold in those collected in poultry houses.

When a host-regulative ectoparasite and a host-regulative endoparasite compete for the same host population (multiple parasitism) the former largely replaces the latter when the host’s density is high, the ectoparasite then being relatively numerous and the endoparasite scarce. However, after the ectoparasite has reduced the host population to a low density the converse is true, the endoparasite being more numerous. This difference is an effect of the endoparasite being able to operate at lower host densities; an essential adaptation if it is to survive competition with a host-regulative ectoparasitic population. The above conclusions are based (1) on the statistical analyses of numerous population samples of ectoparasitic and endoparasitic species of the family Aphelinidae (Chalcidoidea: Hymenoptera) imported into California while inhabiting host coccids (Diaspididae: Homoptera); (2) on field observations by the writer and the reports of others on the numerical status of such hosts and their specific parasites in gardens and orchards in various countries, those in which the species are indigenous as well as in those where they are exotic; (3) on the principles of multiple parasitism as elucidated by Harry S. Smith; and (4) on multiple parasitism by an ectoparasite and a host-specific endoparasite being characterized by the ectoparasite always destroying the endoparasite when both are attacking the same host individual and the endoparasite replacing the ectoparasite when populations of both are subsisting on a low density host population.

Curarized house cricket hearts in semi-isolated preparation are from 10 to 100× more sensitive to the accelerating action of acetylcholine than control hearts. This potentiating effect of curare is similar to that of eserine, and probably acts through inhibition of cholinesterase.

A biotype of the pea aphid was characterized. Two host plants were used: broad bean and pea. It was found that the weight during the development, the survival of adults and their fecundity were better on broad bean as compared to pea.

A new genus and species of Euderinae, Aoridus campbelli n. gen., n. sp., related to Bellerus Walker (Eulophidae: Chalcidoidea) and collected from Colombia, South America, is described and illustrated.

Larvae of Wyeomyia smithii (Coquillett) were collected in Saskatchewan from pitcher-plants in swamps near Nipawin, Little Sandy Lake, and Waskesiu. Pupae and adults also were collected at Nipawin. No trace of W. smithii was found in pitcher-plants in a swamp near Duck Lake. Inconclusive evidence was obtained concerning the presence of W. smithii in a pitcher-plant swamp at Prince Albert.

Larvae of the dark-sided cutworm were collected from trap plants of tobacco set in a field of rye at Delhi, Ont., in 1969. They were reared individually to pupation to determine the degree of survival and the causes of mortality from the fourth instar to maturity. About 36% pupated and the greatest amount of mortality was caused by insect parasitism, a microsporidial disease, and bacterial infection. Fungus and virus diseases were virtually absent. As adult females are capable of laying a large number of eggs, mortality in eggs and young larvae must reach at least 98% to maintain a stable population. Introduction of virus pathogens to attack larvae might well be expected to result in regulating the population at a lower density.

Annual changes in genetic quality were measured in natural populations of Hyphantria cunea Drury for 12 years in New Brunswick and Nova Scotia. Models for heritability and natural selection pressure, derived independently from experimental data, are used to simulate the changes in quality over the same period. In seven of eight areas, observed and simulated trends are significantly correlated. Regressions between observed and calculated values, examined with respect to both means and slopes, suggest how these preliminary models may be refined. The influence of genetic changes on the natural regulation of population density is discussed briefly, but analysis is deferred to a later paper in this series on H. cunea.

Blue, a non-sex-linked mutant of the green lacewing, Chrysopa carnea Stephens, is recessive and shows complete penetrance. Unlike the coloration of the larva or imago, egg colour, which is due to the yolk, is the same as that of the maternal phenotype.

One hundred and sixty species of arthropods, representing 137 insects, 19 mites, and 4 spiders, were collected or reared from the cankers of the comandra blister rust, Cronartium comandrae Peck, on lodgepole pine, Pinus contorta Dougl. var. latifolia Engelm., in southwestern Alberta. The insects damaged 40 to 60% of the cankers observed in any one year and reduced aeciospore production by 10%. Eleven orders of insects were represented, of which the Coleoptera (29 species), Lepidoptera (14), Diptera (21), and Hymenoptera (38) were the most important. Epuraea obliquus Hatch, Paracacoxenus guttatus Hardy and Wheeler, and a Mycodiplosis species appeared to be true mycetobionts. Several others which damaged the cankers, such as Pissodes schwarzi Hopk., Cylindrocopturus deleoni Buchanan, Ernobius sp., Corticaria sp., Bradysia spp., Dioryctria spp., Laspeyresia sp., Grapholitha sp. prob. caeruleana Wlshm., Eucordylea spp., Cinara spp., and Diapterobates principalis (Berlese) could be classied as mycetophiles. About half the species appeared to be mycetoxenes. New habitat or host information was obtained and several new species were collected. Several of the genera represented have been reported to occur on other pine stem rusts, which indicates that the rust cankers provide a suitable habitat for development.