A generalized competition model for predators or parasites was developed from data obtained from a specific parasite–host system. It was structured in three parts. The first simulates the effects of exploitation, where the number of attacks and their distribution among prey or hosts determine how many prey or hosts survive. Since the negative binomial distribution described these distributions consistently, the exploitation submodel was developed from it. The second portion of the competition model concerned interference between searching predators and parasites. Although interference is a universal phenomenon, we were able to show that its effects become important only at predator densities much higher than those that occur in nature. Thus the interference component can be essentially ignored. The third and final component concerned the outcome of competition between parasite progeny within their host. It was developed from Fujii’s competition model which allows for the simulation of both scramble and contest types of competition.These three submodels of competition were combined and coupled with a previously published model of the effects of prey density on attack. In this way the full consequences of different prey and predator densities could be simulated using a model whose constituent parts had been carefully tested for descriptive adequacy. The simulations showed the way individual predator attack, per cent predation, and progeny production were affected by different degrees of contagion in the distribution of attacks, by scramble vs. contest competition, and by the degree to which parasites could avoid hosts already attacked.

Amber of Cretaceous Age from Canada is an exceptionally fine source of well-preserved fossils of a wide variety of insects and related animals. Since these fossils can yield much information about the forms of, and conditions for, life in the Cretaceous Period some 75 million years ago, they represent a highly interesting and valuable scientific resource.The history, relative abundance, nature, biological origin, and significance of Canadian amber is reviewed and related to similar aspects of European or Baltic amber. Reported occurrences of amber in Canada (about 50) are assembled and some 350 arthropod inclusions discovered in the amber collections made thus far are tabulated, with respect to their origins, classification, and present location. The article contains one map, two tables, and 16 figures.

Twenty-two species of insect parasites of Fenusa pusilla (Lepeletier) are listed. Fifteen of these species were reared in the present study from F. pusilla in Quebec, 1 on eggs and 14 on larvae; 4 of them act as both primary and secondary parasites. Of the 15, only 1 has previously been reported as a parasite of F. pusilla. Host–parasite relationship and the degree of parasitism are given for the 15 species reared in Quebec.Thirteen species of predators are listed. Of these, 9, three birds and six insects, were observed feeding on F. pusilla larvae during this study.

Five particle types of tetradiphon, three of chloropropylate, and two of Pentac (bis(pentachloro-2,4-cyclopentadien-1,yl) were prepared in similar formulations and tested as sprays against different stages of Tetranychus urticae Koch on bean leaves. The residual, combined topical and residual, and the systemic effects of the formulations were recorded. The target sizes presented by T. urticae stages and by the ranges over which they moved and fed were determined and the numbers of particles per unit area deposited on bean leaves by the formulations used, counted. Positive correlations were shown in all instances between smallness of particle size, number of particles per unit area, and effectiveness, but the relationships between these factors were complex. It is concluded that effectiveness is influenced by a number of factors of which particle size and shape are two which are important but that their effects are often greatly modified by some of the other factors.

Radionuclides may be used as ecological tracers to study trophic–level relationships. To use cesium-137 to investigate the role of the giant water bug, Lethocerus americanus (Leidy), in the food-web of a small pond, it was necessary to measure the elimination rate of the nuclide. The experimental determination of the elimination rate of cesium-137 in fourth instar and adult water bugs, and the calculation of the fraction of ingested food assimilated is described.

The sexes of all but three of the North American species of Ips DeGeer can be separated reliably using characters on the frons, vertex of the head, protibiae, or declivital armature. In general, these secondary sexual characters are consistent within Hopping’s species groups.

The alder bark beetle, Alniphagus aspericollis (LeConte), is bivoltine on Burnaby Mountain, B.C. The principal spring attack occurred in May and the second generation attack from mid July to early August. Mature adults overwinter in shallow galleries underneath the bark while larvae, pupae, and callow adults overwinter in the brood galleries. Sporadic emergence occurred in warm periods throughout the winter but the first egg galleries were not observed until early March. Windfalls and standing trees were attacked.Adult sexes can be distinguished by the fused (female) or separate (male) seventh and eighth abdominal tergites. Females attack the host first and are soon joined by the males. Single egg galleries extending about 8 cm parallel to the length of the bole are most common. Eggs are laid on both sides of the gallery; the larvae mine outward at right angles to the egg gallery and then usually up or down the bole. Adult gallery construction and oviposition and larval mining habits were observed through plexiglass–bark "sandwiches," and are similar to those in the genus Ips. Pupation occurs in a chamber in the inner bark. Maturation from egg to callow adult required a minimum of 8 weeks.

The gas chromatograms of some of the volatile chemicals found in the following ants are presented: Pogonomyrmex barbatus (F. Smith), Forelius foetida (Buckley), Conomyrma pyramica (Roger), Iridomyrmex pruinosus analis (E. André), Tapinoma sessile (Say), Trachymyrmex septentrionalis obscura (Wheeler), Pheidole dentata Mayr, Acromyrmex versicolor (Pergunda), and Novomessor cockerelli (E. André). The data and methods are presented to demonstrate their potential value as taxonomic characters in the study of ant systematics.

Populations of the balsam woolly aphid on Fraser fir trees were sampled without replacement. Sampling frequency was based on the embryological period of the aphid at mean monthly temperatures in the field. The sample for each date consisted of 16 pieces of bark, 1/2 in. diameter, from each of 10 trees. Precision of the method was usually within ±10% of the mean. The largest proportion of variance was within trees. Stratification of samples by levels within trees decreased variance estimates.Frequency distributions of counts of most stages of the aphid approximated the negative binomial distribution. Therefore, data were transformed to logarithms in order to approximate the normal distribution.

The genus Melocosa Gertsch, 1937, is transferred from Pisauridae to Lycosinae in the Lycosidae. The genus Melocosa is defined, and its characteristics indicate relationship to the genus Tarentula. Male and female specimens of the type species are described in detail and drawings of diagnostic characteristics are given. A key to the Nearctic genera of Lycosidae is given.

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.