A generalized competition model for predators or parasites was developedfrom data obtained from a specific parasite–host system. It was structuredin three parts. The first simulates the effects of exploitation, where thenumber of attacks and their distribution among prey or hosts determine howmany prey or hosts survive. Since the negative binomial distributiondescribed these distributions consistently, the exploitation submodel wasdeveloped from it. The second portion of the competition model concernedinterference between searching predators and parasites. Althoughinterference is a universal phenomenon, we were able to show that itseffects become important only at predator densities much higher than thosethat occur in nature. Thus the interference component can be essentiallyignored. The third and final component concerned the outcome of competitionbetween parasite progeny within their host. It was developed from Fujii’scompetition model which allows for the simulation of both scramble andcontest types of competition.These three submodels of competition werecombined and coupled with a previously published model of the effects ofprey density on attack. In this way the full consequences of different preyand predator densities could be simulated using a model whose constituentparts had been carefully tested for descriptive adequacy. The simulationsshowed the way individual predator attack, per cent predation, and progenyproduction were affected by different degrees of contagion in thedistribution of attacks, by scramble vs. contest competition, and by thedegree to which parasites could avoid hosts already attacked.

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

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

Five particle types of tetradiphon, three of chloropropylate, and two ofPentac (bis(pentachloro-2,4-cyclopentadien-1,yl) were prepared in similarformulations 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 formulationswere recorded. The target sizes presented by T. urticae stages and by the ranges over which they movedand fed were determined and the numbers of particles per unit area depositedon bean leaves by the formulations used, counted. Positive correlations wereshown in all instances between smallness of particle size, number ofparticles per unit area, and effectiveness, but the relationships betweenthese factors were complex. It is concluded that effectiveness is influencedby a number of factors of which particle size and shape are two which areimportant but that their effects are often greatly modified by some of theother factors.

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

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

The alder bark beetle, Alniphagus aspericollis (LeConte),is bivoltine on Burnaby Mountain, B.C. The principal spring attack occurredin May and the second generation attack from mid July to early August.Mature adults overwinter in shallow galleries underneath the bark whilelarvae, pupae, and callow adults overwinter in the brood galleries. Sporadicemergence occurred in warm periods throughout the winter but the first egggalleries were not observed until early March. Windfalls and standing treeswere attacked.Adult sexes can be distinguished by the fused (female) orseparate (male) seventh and eighth abdominal tergites. Females attack thehost first and are soon joined by the males. Single egg galleries extendingabout 8 cm parallel to the length of the bole are most common. Eggs are laidon both sides of the gallery; the larvae mine outward at right angles to theegg gallery and then usually up or down the bole. Adult gallery constructionand oviposition and larval mining habits were observed throughplexiglass–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 thefollowing 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 methodsare presented to demonstrate their potential value as taxonomic charactersin the study of ant systematics.

Populations of the balsam woolly aphid on Fraser fir trees were sampledwithout replacement. Sampling frequency was based on the embryologicalperiod of the aphid at mean monthly temperatures in the field. The samplefor each date consisted of 16 pieces of bark, 1/2 in. diameter, from each of10 trees. Precision of the method was usually within ±10% of the mean. Thelargest proportion of variance was within trees. Stratification of samplesby levels within trees decreased variance estimates.Frequency distributionsof counts of most stages of the aphid approximated the negative binomialdistribution. Therefore, data were transformed to logarithms in order toapproximate the normal distribution.

The genus Melocosa Gertsch, 1937, is transferred fromPisauridae to Lycosinae in the Lycosidae. The genus Melocosa is defined, and its characteristics indicaterelationship to the genus Tarentula. Male and femalespecimens of the type species are described in detail and drawings ofdiagnostic characteristics are given. A key to the Nearctic genera ofLycosidae is given.

A non-diapause strain of the migratory grasshopper, Melanoplus sanguinipes (Fabr.), has been developed over the past 12 yearsby selecting for rearing those grasshoppers that hatched from eggs notpreviously cooled. Because this strain can be reproduced at the rate of sixto seven generations per year it is proving to be a useful experimentalanimal.