Only a few studies have been made on the external morphology of both the adults and larva of a single species of sawfly, viz.: Hoplocampa balcyon (Nort.) (Bird 1926; 1927); Lygaeonematus subarcticus Forsl. (Forsslund 1936); Diprion pini (L.) (Arora 1953; 1959); Cephalcia marginata Middlekauff (Rivard 1955); and Taxonus agrorum Fallén (Ciampolini 1957). The following paper presents a detailed study of the external morphology of the larch sawfly, Pristiphora erichsonii (Htg.) and represents a consolidated revision of interim technical reports prepared earlier (Wong 1958a; 1958b). A recent paper by Bracken (1961) drew heavily from the wording and organization of the earlier of these reports for description of the external morphology of the adults of Anoplonyx luteipes (Cress.) and A. canadensis Harr. Unfortunately, Bracken incorporated minor morphological misinterpretations that have been corrected in the present paper.

Studies were made on the distribution and survival of the mountain pine beetle over the lower stem of lodgepole pine. The relationship between density of attack and subsequent total length of egg galleries was examined as was the relationship between number of exit holes and number of emerging beetles. The influence on brood survival of tree diameter, density of egg galleries, moisture content of the outer sapwood, lethal temperatures, resinosis in the subcortical region, predators, and parasites is described. Survival is compared between broods established during different flights in the same year. The optimum weather conditions for brood survival are discussed.

When the Zeugloptera are compared with advanced Lepidoptera three major changes in the hind wing base are noticed:

1) The apparent loss of the prescutal arm which is fused to the second basalare in Ditrysia.

2) The separation of the prescutal apodeme from the prescutum by membrane so that the third tergopleural muscle appears to insert on the mesopostnotum.

3) The reduction of the median plates and the development of cubital plates.

Experiments were designed to find the functional response (response per predator) of the pentatomid Podisus maculiventris to the population density of larvae of the fall webworm, Hyphantria cunea. The response was measured in confined universes, (glass jars), representing webworm nests, and it was found permissible to vary universe size, within certain limits, in order to obtain a wide range of prey densities without handling large numbers of larvae. The “disc equation” proposed by Holling (1959) was found to describe the response curves, except at very high prey densities, and to provide a satisfactory biological explanation for their decreasing slopes. P. maculiventris ingests about 84% of its own weight for each fifth-instar larva of H. cunea attacked successfully, and the time spent in feeding and becoming hungry enough to make another attack reduces very substantially the time devoted to searching activities. Both prey defense (Fig. 1) and the age of the adult predator (Fig. 2) have very important effects on the functional response curves and on the values of the parameters, a and b, of the disc equation. These effects are explained. The “rate of discovery”, a, is contrasted to Nicholson's (1933) “area of discovery” and it is shown why the former is more likely to be independent of prey density than the latter.

In view of the population of webworm larvae in the average nest, it is concluded that the functional response of the various predators inside the nest is probably not important, and that attention should be devoted instead to the functional and numerical responses of predators and parasites to the density of nests per unit area. Because of the vigorous defense exhibited by fifth-instar webworm larvae, predation by timid predators like P. maculiventris is selective and larvae whose development is delayed by parasitism are likely to suffer more predation than healthy larvae.

This paper contains the description of seven new genera and 26 new species of Ethiopian Lygaeidae. Keys to species are given where possible and a key to the genera of the Clerada complex of Cleradini is provided. The genus Mahisa Distant is resurrected from synonymy and Migdilybs furcifer var. capensis Hesse is raised to specific status.

Rearing techniques were developed and apparatuses built for biological studies on the Elateridae in the organic soils of southwestern Quebec. Adults attracted to heap-traps are normally mixed with a large quantity of hay trash which makes the recovery of beetles tedious and difficult. To facilitate this work, an insect sorting box was designed and built and proved quite satisfactory. A flight-trap was also designed for obtaining information on adult species concerning their period of emergence, peak and length of emergence, and height and direction of flight. Adequate techniques for the incubation of wireworm eggs and the rearing of larvae under constant supply of water through capillary action were developed. A large field cage was designed and built to study under natural conditions the complete life-cycle of the species of elaterids found in organic soils.

Air from a common source was divided and each portion blown through a separate large box containing, except for an empty control, logs from one tree species. Air from each box was conducted away and released between two window flight traps. Four coniferous tree species were represented in the test. Bark and ambrosia beetles from natural populations responded positively to log odors in the released air. There were differences in the response of beetle species to the log odors represented.

Considerable evidence substantiates the idea that native pests can be controlled by parasites and predators of allied species and genera. In a survey of 66 pest species, which were successfully controlled by biological means and for which the habitats of all species could be verified, it was found that 39% were controlled by an introduced parasite or predator of an allied species or genus. Although relatively few attempts have been made to control native and imported pests with parasites and predators of species allied to the pest species, the proportion of successes is surprisingly high. Employing these species has certain advantages, especially in the control of imported pests, because no ecological homeostasis has evolved and the association between the parasite and host (predator and prey included) is new.

Four ichneumonid species, Itoplectis conquisitor (Say), Pimpla pedalis Cress., Theronia atalantae (Poda), and Theronia hilaris (Say), were seen attacking the gypsy moth, Porthetria dispar (L.), in the Town of Glenville, Schenectady County, New York. These species stung and killed many more host pupae than they successfully parasitized (success here being measured by the development of an ichneumonid offspring within the host). The ratio between the total number of hosts stung by ichneumonids and the number of ichneumonid offspring emerging was different for each of the three primary ichneumonids studied, ranging from 4 to 1 for T. atalantae to more than 200 to 1 for I. conquisitor.

The sarcophagids associated with the gypsy moth, although apparently parasitic, are largely scavengers. Their attacks almost always follow those of ichneumonids. Since the sting by an ichneumonid kills the host but is not always discernible, the number of pupae containing sarcophagid larvae has been used to, indicate the true effects of ichneumonids on the host population.

The possibilities of using genetic principles to improve biotic agents used in biological control are discussed, and a number of examples quoted where possibly useful racial differences between parasites occur.

However, the main conclusion is that in introductions of biotic agents the principal aim should be to have as much genetic variability as possible in the material released, rather than to try and select a priori certain apparently suitable strains.

Adults of B. cephi emerged at the same time as the adults of their host, the wheat stem sawfly, and started to oviposit about mid-July. The second generation started to emerge between August 5 and 15. This generation, which was complete in some years, was apparently only partial in years in which adults of the first generation continued to oviposit late in the season. In most cases the larvae of Bracon that were present at harvest time were from eggs laid after August 1.

Most of the overwintering B. cephi were located in the lower internodes of the sawfly-infested wheat stems. Although B. cephi attacked some sawfly larvae in their stubs most sawflies escaped parasitism once they had cut their host stems.

High host densities per stem in hollow-stemmed wheats were detrimental to Bracon during the early part of the season as the unparasitized sawfly larvae in stems containing B. cephi destroyed the parasite larvae.

The sawfly-susceptible wheats were more suitable than the resistant for parasitism. Generally, differences in parasitism between wheats and between barleys were caused by differences in length of survival of the sawfly larvae in the different host plants; longer survival led to higher parasitism.

The fluctuations in amounts of parasitism mainly depended on the synchronization of development between B. cephi and the sawfly. Parasitism increased when the sawfly larvae cut their host stems sufficiently late to allow establishment by the second generation of B. cephi and decreased when the sawfly cut too early for parasitism by the second generation. The date of ripening of the host plant governs the date of cutting by the sawfly; hence, the amount of parasitism is influenced by the levels of soil moisture and temperature during the growing season, by differences in rate of development of various plant hosts, and by the date of seeding. Low levels of parasitism resulted from early ripening of the sawfly host plants in two consecutive years, whereas a moderately high level occurred even though the weather of the current year was conducive to early ripening, provided that the wheat in the preceding year had ripened late. It appears that moderate to high levels of parasitism required that the crop ripen late in at least one year out of two.

Eighteen species are listed of which eight are described as new. Most of these species were collected in the more southerly parts of the Canadian Arctic, but two species were collected at Lake Hazen which is situated in the extreme northeastern portion of Ellesmere Island. The majority of the species belong to well known Holarctic genera. Characteristically Palaearctic groups are represented by five species, but exclusively Nearctic groups are represented by a single species. The most conspicuous biological feature is the apparent reversal of the switch mechanism governing the production of sexuales since, in spite of the excessively long photoperiod, oviparae are common.

The susceptibility of the spruce budworm, Choristoneura fmiferana (Clemens), under laboratory conditions, to commercial preparations of Bacillus thuringiensis var. thuringiensis Berliner was reported by Angus et al. in 1961. This bacterium was recently tested, under field conditions, both as dusts and sprays. The results of ehese tests are presented here with comments on the effect of the environment and other factors.

During a study on the population dynamics of the gypsy moth, Porthetria dispar (L.), conducted in the Town of Glenville, New York, some factors were found to affect the sexes differentially. The importance of this differential mortality is indicated by the fact that 78 per cent of the variation in the logarithm of an index of population trend (the ratio of population density from year to year) was associated with the logarithm of adult sex ratio.

Disease and desiccation during instars IV-VI and among pre-pupae were strongly selective against the female insects. This differential mortality caused a change in the pupal sex ratio from about 70 per cent females where no disease occurred to less than 25 per cent female pupae following an epizoötic. Ichneumonids, on the other hand, usually killed more male pupae than females, except when host size was reduced by excessive larval density and competition. The net result from this series of factors that distort the sex ratio has been to produce adult sex ratios varying from more than 80 per cent female moths to only 2 per cent females.

In this host species, as in most other animals, it seems that the population consequences of a mortality factor that kills the host sexes in different proportions should be evaluated in terms of the more critical (female) sex destroyed.

It is well known that the membranous areas of lepidopterous larvae may lose much of their colour pigment when the larvae are preserved, but it appears to be less widely recognized that the larvae themselves mav also be burned by the preservative. A pale larva, one that is greenish or yellowish when alive and almost cream-coloured when preserved, becomes brownish under these circumstances. The colour change may be so pronounced as to result in mis-identification of the species, and a colour description based on a series of such larvae may be most inaccurate.

Granular heptachlor applied with the seed caused mortality in larvae of the wheat stem sawfly, Cephus cinctus Nort., in wheat stems. Half a pound of actual heptachlor per acre gave less control than either 1 or 2 pounds, although the latter two rates did not differ in effectiveness. Formulations with attaclay were more effective than with vermiculite.

The insecticide was most effective in the lower internodes of the stem where it caused considerable mortality of early-instar larvae but was less effective on more mature larvae.

To be effective, heptachlor evidently required light sawfly infestations restricted mainly to the lower internodes of the stems such as had occurred in 1960. In that year heptachlor gave its best control although it was no more effective than a moderately sawfly-resistant wheat. Lack of control in 1961 was related to the heavy sawfly infestations in that year. The poor control in 1962 was related to the concentration of most of the sawfly eggs in the top two internodes where the insecticide had little effect on newly-hatched larvae. Only later, when they were more mature, did the larvae reach the lower internodes.

Oviposition and fecundity of Cteniecra destructor (Brown) were studied in the laboratory and field. In a series of tests, total oviposition by individual field-collected females ranged from 495 to 1464 and averaged from 264.0 to 940.0 eggs per female. Temperatures from 50 to 86° F. had no effect on total fecundity but lower temperatures extended the oviposition period. Soil moisture from 8 to 20% in sifted clay loam soil (particle sine less than 0.177 mm.) had no effect on total oviposition. At 4% soil moisture females died rapidly and laid very few eggs. Food increased the total oviposition, the length of the oviposition period, and the longevity of females. Most eggs were laid during the first month after the onset of oviposition.

Oviposition was shown to be cyclic in nature. Females usually laid eggs in large batches, followed by periods when practically no eggs were laid. This resulted in a series of irregular oviposition peaks which gradually declined in magnitude as the oviposition period progressed.

Comparisons of ecologic communities are often limited to presentations of frequency lists in tabular or bar-graph form. Kendall's “Tau” coefficient is appropriate as a measure of rank correlation between such numerical profiles. A special problem arises where species in one community are absent from the other. Such species may either be assigned zero frequency and last-place ranking in the community where they are absent, or they may be dropped from both rankings, depending on which method yields the more conservative correlation. Tau has the same limits (± 1) as the familiar product-moment correlation coefficient. Moreover, as a nonparametric statistic it is free of considerations of distribution. Comparisons between soil-fauna communities from the Quetico-Superior forest area are used to illustrate the method. The problems of tied rankings, variance and significance of Tau, confidence limits for Tau, and the significance of a difference between Tau coefficients, are also considered.

The new tribe Athyreini is established in the subfamily Geotrupinae, family Scarabaeidae. The genus Athyreus MacLeay is delimited and three new genera, Pseudoathyreus, Parathyreus and Neoathyreus, are proposed.

The extant types of chalcids described by Provancher are re-examined. A few are lost or so badly damaged that accurate placement is now impossible, but the majority of species are correctly identified in modern literature. Five new combinations and nine new synonymies are proposed.