A resumé of the North American literature concerned with hymenopterous parasites of bark beetles is presented. Morphology, seasonal history, host-tree selection, hyperparasitism, importation and colonization and their influence upon control of the host are briefly discussed.

Parasites of a given host or hosts of a known parasite can easily be found in two different lists. Parasites are listed below in an alphabetical list of bark beetle species. Hosts, including some species other than bark beetles, are listed under a separate list of parasite families and genera. Host-parasite associations in each list are supported by a numerical reference to the literature cited.

The generic characters of Eumacronychia are reviewed and as here considered the genus includes 21 nominal forms of which 9 are described as new. All members are quite similar in habitus and difficult to distinguish except by reference to the male terminalia. A key to all known species is included to facilitate identification. The maximum distribution of the genus is centered in the southwestern United States with the present known extreme range extending from Canada to Guatamala.

Mites of the genus Phytoseius Ribaga largely inhabit plants and are at least partly predacious, feeding on tetranychid, eriophyid, and other mites. They probably also feed on pollen, honeydew, and plant juices, as do other phytoseiids that have been studied (Chant 1959; Dosse 1961; McMurty and Scriven 1964). They are not usually found in soil or humus but occur on many kinds of low growing plants as well as coniferous and deciduous trees. They have been collected on all continents and from the arctic to the tropics.

The 40 known species of the genus Xysticus C. L. Koch that occur in Canada are described and illustrated. Keys to both sexes are provided. Three new species, X. ampullatus, X. leechi, and X. winnipegensis, are described, two species, X. lutulentus Gertsch and X. nicholsi Gertsch, are synonymized with previously described ones, and two, X. ellipticus new name and X. alboniger new name, are transferred to Xysticus from another genus.

Three species are recognized in the North American genus Megetra LeConte. The most distinctive of these anatomically and ecologically is M. cancellata (Brandt and Erichson), which ranges discontinuously from Arizona and New Mexico to the state of Hidalgo in México and occurs in limited sympatry with both of its congeners. Megetra vittata (LeConte) ranges from northern Arizona to western Texas. It appears to be strictly allopatric with, and similar ecologically to, M. punctata, new species, which ranges from southern Arizona and New Mexico to Durango, México. Specific diagnoses are made on the basis of characters of adult and, for M. cancellata and M. punctata, larval anatomy. Intraspecific variation in several adult characters is analyzed. Notes on the seasonal distribution, habitat, and behavior of the adult beetles are included.

Aphids of the genus Cinara are capable of causing serious growth reduction of Douglas-fir seedlings. Growth of infested seedlings may be only one-fourth to one-half that of uninfested seedlings. The aphids are easily controlled by injecting demeton around the base of the seedling. The presence of ants to clean up excessive honeydew is shown to be beneficial for the aphids.

All, postembryonic instars of Hoploseius tenuis n. sp. are described and illustrated. This species is numerous in the pores of coniferous bracket fungi where it presumably feeds on the fungus. Discussed are: the relationship of this species to congeners, and the modification of the generic concept; the ontogeny of the body and leg setation, which includes larval, pustlarval and regressive deficiencies, and retardation; and the ontogeny of body elongation and its effect on the positions of setae. The adult morphology and setation of H. tenuis is briefly compared with that of an elongate digamasellid, Longoseius cuniculus Chant.

A new genus, Pseudasiphonaphis, is described, with type species Asiphonaphis anogis Hottes and Frison, 1931. Two new species are described, Macrosiphum olmsteadi from Aster spp., and Macrosiphum (Sitobion) manitobensis from Cornus stolonifera Michx. Descriptions of previously undescribed fundatrix, ovipara and male of Masonaphis wahnaga (Hottes), and ovipara and male of Dactynotus richardsi Robinson are also given.

The ochrogaster group of the genus Euxoa is defined on the basis of genitalic characters, and a new species closely related to Euxoa ochrogaster (Guenée) is described from the Yukon and western Northwest Territories of Canada.

Three new species are described; two European species, tringarius L. and lineola Fabr., are recorded for the first time; and the previously described species are redefined and new distribution records presented, with a key to the eastern species. Rhagio hirtus Loew is recognized as a good species, R. boscii Macquart and Xylophagus fasciatus Say are synonymized with albicornis Say, and R. intermedius Walker is synonymized with R. vertebratus Say. The three new species are R. dichromaticus from Louisiana, recognized by its extremely dark coloration; R. floridensis from Florida and Georgia, with yellow thorax and distinctively patterned wings; and R. orestes from Great Smoky Mountains National Park, which is close to hirtus but separable by the darker thorax and abdomen.

The systematic position of the North American species described, originally, in the genus Trioxys Haliday is discussed. The following nine taxa are of genus Trioxys sensu strictu: T. (Trioxys) ameraceris Smith, betulae Marshall, new RECORD, bonnevillensis Smith, exareolatus (Viereck), gahani Smith, ibis Mackauer, NEW RECORD, infrequens Smith, utilis Muesebeck; and T. (Betuloxys) compressicornis Ruthe, NEW RECORD. Six species fall into genus Binodoxys Mackauer: B. carolinensis (Smith), coruscanigrans (Gahan), cupressicola (Gahan), NEW COMB., nearctaphidisN. SP., palmerae (Smith), and rhagii (Ashmead).

The different types of individuals among the progeny of the western tent caterpillar, Malacosoma pluviale (Dyar), are concentrated in different parts of the egg mass. The most agile progeny come from some of the first eggs laid, and the least viable are among the last deposited. There is evidence that this serial arrangement stems from unequal partitioning of the maternal food reserves during egg production: a relationship similar to that recently demonstrated in the spruce budworm by I. M. Campbell. In M. pluviale, however, there also is evidence that the differences in feeding rate and food capacity displayed by the different types of females during their own larval stage affect the proportions of the various types of progeny per egg mass as well as the viability of consecutive groups of eggs within the mass. Although these maternal influences are not heritable in the usual genetic sense, they are clearly transmissible between generations. And field studies have shown that their more adverse consequences for local populations are cumulative and ultimately lethal.

In southern Alberta, the distribution of Bombus (Bombias) auricomis is confined to wooded areas whereas that of B. (Bombias) nevadensis encompasses prairie and wooded areas. Perhaps B. nevadensis survives on the prairie because it hibernates well below the surface of the soil.

When given equal opportunity to nest in surface or underground hives, B. nevadensis nested in three surface and 18 underground hives. Both species began to establish nests between mid-May and mid-June.

Both species laid one egg per cell in all broods, vertically in the first brood and horizontally in later broods. Larvae were fed individually in all instars of all broods, except perhaps during early instars of the first brood when pollen was packed beneath them through pockets made at both ends of the brood mass.

The eggs in the first brood layer were usually laid within 4 days. The cells beneath the shallow incubation groove were usually the first made and the ones from which adults first emerged. Queens of B. nevadensis required about a month to rear sufficient workers to take care of the foraging duties of the new colonies. Egg cells of succeeding broods were built side by side in groups or lines on cocoons of previous broods and were not primed with pollen.

Both species were prolific producers of wax. More pots for the storage of honey and pollen were added as colonies increased in size.

Colonies of both species were usually small, apparently because the queens usually found time to rear only one brood of workers and perhaps because only one egg was laid in each cell. The largest colony, of B. nevadensis, produced 139 individuals. The workers of a brood sometimes varied greatly in size. The workers of succeeding broods were progressively larger, the last ones produced being almost as large as queens. Males of B. nevadensis mated by grasping the queens when they were flying, then copulating on the ground. After mating, queens hibernated at a depth of about 3 inches in the soil.

Males and females of Psithyrus insularis were reared in nests of B. nevadensis. P. suckleyi also established in a nest of this species. The big-headed fly, Physocephala texana, was a destroyer of B. nevadensis. Ants pillaged first broods not protected with an insecticide.

Six species of Proctolaelaps, found associated with insect pests of pine forests in the southeastern United States, are described and illustrated. These are: P. bickleyi (Bram), P. fiseri Samšinák, P. hystrix (Vitzthum), and three new species, P. dendroctoni, P. dioryctriae, and P. hystricoides. Newly recorded for North America are P. fiseri, P. hystrix, and P. ulmi Hirschmann; distributions for the last two species include British Columbia. Garmania striata Westerboer is synonymized under P. bickleyi; the problem of the lewisi species complex, which includes P. bickleyi, P. lewisi (Garman and McGregor), and P. utahensis (Chant), is noted.

Although the food habits of these and related mites are mostly unstudied, tentative observations indicate that some species are commensals and others are predators of their insect associates. Investigation of such mites and their relationships with forest pests is urged.

Progeny of individual females of Lecanium spp. from orchard, ornamental, and wild trees and shrubs were colonized on rooted willow cuttings in a greenhouse and insectary. Some forms with distinctive morphological and colour characters on their original hosts maintained these characters through one to six generations on willow. These results and many years’ observations indicated that lecanium scale infestations in fruit orchards of the Niagara Peninsula, Ontario, were usually composed of a complex of forms. Some of these were distinct species but others, less sharply differentiated, were considered as varieties of these species. One new species is described.

A series of laboratory toxicological experiments using various concentrations of oil formulated DDT solutions (AR-50/fuel oil (2:7 V/V)) was carried out on 5th and 6th instar spruce budworm larvae collected in the field from DDT-sprayed and untreated areas of New Brunswick, Canada, and Maine, U.S.A.

Results obtained in 1959, 1961, and 1962 with larvae collected from isolated, unsprayed areas in New Brunswick showed a consistent, straight log-dosage probit mortality curve. Larvae collected in 1962 and 1963 from infestation centres previously subjected to three, four, and five applications of non-consecutive large-scale aerial sprays of DDT showed a significant departure from the straight log-dosage probit curve previously obtained. The departure occurs as a change in the shape of the curve as well as a shift to the higher concentration range of DDT. The magnitude of change appears to be correlated with the number of sprays to which the population was exposed. Results obtained in 1962 and 1963, from untreated control and inter-spray areas, bounded by DDT-sprayed forest lands, showed a small but significant departure from the normal straight probit line of a susceptible population. These changes are indicative of a progressive development of DDT resistance in wild populations of spruce budworm.

Studies on the effect of the tolerance of spruce budworm larvae within instar classes to the action of DDT showed that the early phase of instar development immediately after moulting is more susceptible to the action of DDT, whereas the latter phase of instar development immediately prior to moulting is more tolerant to topical application of DDT than the average for the instar. This effect is evident in both susceptible and resistant populations.

The data interpretation assumes that a deviation from the straight line probit dosage – mortality curve is indicative of a difference in the DDT-susceptibility factor of the budworm population and that in the course of the tests, the amount of toxicant causing mortality was not proportional to the dosage.

Udamopyga boniato, new species (Cuba) and U. batemani, new species (Mexico) are described and U. niagarana (Parker) refigured. A revision of Lopes’ (1940) key is presented to include them.

A new species of Ips is described and illustrated. This species is allied to I. interrupta and I. hunteri and is found attacking freshly dead or dying limber pine, (Pinus flexilus).

Gastromermis boophthorae is distinguished from related species by its longer spicule, its characteristic lateral cord, numerous and small cells in the head region, and longer proximal reflex of the vagina. This species is divided into six varieties that are based mainly on differences occurring in the free-living postparasitic stages. It is recognized that the term “variety” is seldom used in nematology and is unprotected nomenclatorially, but its use here seems justified to designate infraspecific populations that appear at present to be sympatric and anatomically discontinuous, and that can only be recognized as immature nematodes. Six species of blackflies were found to be hosts and infection is reported from May until August in the Leningrad region. Percent infection ranged from 1 to 10 but reached 100% in one sample. Synchronization of host and parasite development is probably important in determining incidence of parasitism.

Existing theories and conclusions on the taxonomic relationships between various aphids are based on a study of those insects alone, and are often a matter of opinion.

True taxonomic relationships frequently are revealed when the host ranges of the insect parasites of aphids are considered.

Conclusions from a study of the host-relationships of aphid parasites of the family Aphidiidae (Hymenoptera: Ichneumonoidea): support the division of the superfamily Aphidoidea into Phylloxerina and Aphidina; support that Chaitophoridae, Callaphididae and Aphididae (including Lachnidae) form a monophyletic group, with the Aphididae the most recent member; support the view that the Rosaceae complex of Aphididae is natural; show that the aphid host plant usually has no decisive influence on the potential host range of an aphidiid species, even in cases of a taxonomically discontinuous change in host plants; and do not support the placement of the genus Drepanosiphum with the family Callaphididae, subfamily Phyllaphidinae.