The subgenus Chrysocharis s. str. in America north of Mexico consists of 18 species. Of these, six are new: Chrysocharis beckeri, subcircularis, bellincus, clarkae, truncatipennis, and levipectus. The name giraulti is proposed for petiolata Girault nec Förster. Key to species, descriptions, host records, and illustrations are included. Relationships of species-groups of North America and Europe are discussed.

Telenomus reynoldsi n. sp. (Scelionidae: Telenominae) is described as an egg parasite of Geocoris punctipes Say and G. pallens Stål in California. The parasite has been recovered from cotton fields at Thermal and Indio, and from strawberry fields at El Toro, California. Additional material deposited in the U.S. National Museum of Natural History has been recovered from Geocoris collected at Buttonwillow and Weed, California.

Aphalara monticola sp. n. is described from 37 ♂ and 49 ♀ collected from Rumex pauciflorus Nutt. in the Kananaskis Valley, Alberta, Canada. A. monticola is closely related to the Nearctic A. rumicis Mally and the Palaearctic A. exilis (Weber & Mohr).

A new genus, Knightomiris, is proposed for Lygus distinctus Knight. Diagnostic features of the genus, male genitalia and the adult of distinctus are figured, and additional records on distribution are given.

The following new taxa of Quediini (Staphylinidae) are described: Quedius (Megaquedius) syphax spec. nov. (Washington), and Acylophorus (Acylophorus) pusillus spec. nov. (Florida).

The following new synonymy is established: Quedius (Quedius) neomolochinus Korge, 1962 is identical with Quedius (Quedius) laticollis (Gravenhorst, 1802).

Additional data on taxonomy, bionomics, and geographical distribution of many species are presented.

Two fungi, Entomophthora sphaerosperma and E. egressa, were collected and identified from larvae of the eastern hemlock looper, Lambdina f. fiscellaria (Guen.), in Newfoundland. These two fungi appear to play the most important role in the decline of looper infestations. Field trials indicate that the disease can be transmitted from laboratory-reared larvae artificially infected with the protoplast stage of E. egressa, to uninfected larvae. This suggests that infection may be established artificially within a population of the looper prior to the ’natural’ occurrence of the epizootic.

The life cycles and larval feeding habits of Leucopis (Neoleucopis) pinicola Malloch and Chamaemyia polystigma Meigen were studied in northeastern Ohio. The larval stages of L. pinicola are predators of the pine bark aphid, Pineus strobi (Hartig) (Homoptera: Adelgidae). Probably there are only two generations a year, and overwintering occurs as mature larvae or pupae that are in diapause. Larvae of C. polystigma prey on the blue grass mealybug, Heterococcus nudus Green (Homoptera: Pseudococcidae), that infests perennial rye grass, Lolium perenne L. This species has three generations a year and overwinters as diapausing mature larvae and pupae.

The eggs, three larval instars, and puparia of both species are described and illustrated.

The larval parasite complex of Ips paraconfusus Lanier is found to differ in Pinus ponderosa and Pinus lambertiana within the same local area. Ips paraconfusus was attacked by fewer species of parasites in ponderosa pine and the rate of parasitization was generally less in that tree species. Greater parasitization in sugar pine was not entirely accounted for by the additional parasite species, but also reflected greater efficacy by those species common to both trees. Evidence indicates that greater bark thickness in ponderosa pine at comparable diameters may have been responsible for the higher parasitization by the shared parasite species.

A significant negative regression of parasitization with diameter was found in sugar pine, but not in ponderosa pine. Most, if not all, of this regression is attributed to a single species, Rhopalicus pulchripennis, whose searching appears to be confined to the smooth, softer bark of the crown.

Populations of the fir engraver reached epidemic proportions and then declined to a very low level over the study period (1964–71). However, population density within infested trees showed an inverse relationship to overall population trend. The population trend over the past 40 years was associated to some degree with rainfall deficits and with Douglas-fir tussock moth outbreaks.

The major contribution to total mortality in each generation occurred in the larval, pupal and pre-emergent adult stages, next was adult mortality and infecundity, while egg mortality was of least significance. Mortality and infertility of parent females was mainly caused by nematode parasites although host resistance resulted in a significant number of attack failures. Parasitism by a phorid fly was of minor importance. Nematode parasitism appeared to be density-dependent in relation to overall population size.

Most egg mortality resulted from host resistance which was inversely related to egg density within trees. Other egg mortality occurred in a density-independent manner.

Mortality between larva and brood adult stages was mainly attributed to intra- and interspecific competition. The impact of these factors was directly related to within-tree larval density. Nematode parasitism was related to overall fir engraver population size and to per cent infection of attacking females. Predator activity was weakly density-dependent and mortality caused by resinosis was inversely related to fir engraver density. Parasitism and other mortality factors appeared to be independent of host density.

An hypothesis is presented for the population behavior of the fir engraver; population fluctuations being determined by the quantity of susceptible trees and ultimately regulated by intraspecific competition. Nematode parasitism and interspecific competition were regarded as modifying, and perhaps sometimes regulating, abundance. Areas needing additional study, particularly host-tree physiology are discussed.