Resistance to the initiation of feeding by newly hatched larvae of Hylemya brassicae (Bouché) confined on surfaces of rutabaga roots was examined. Differences between varieties could be distinguished by using 10 larvae on a root segment. There were no differences between roots within a variety or between portions of one root. The evidence of resistance in Wilhelmsburger was confirmed. This technique of rearing on a small surface area of the root may be valuable in evaluating lines in the laboratory without destroying their propagation value.

In Tanyderidae, Blepharoceridae, and Cylindrotominae, the aedeagus of the male carries three seminal ducts which open independently. In the female, similarly, there are three spermathecae and their ducts lead to independent openings on the ninth sternum, spaced to correspond to those of the male. The aedeagal ducts are very narrow and arise from an ejaculatory pump supplied by the common duct of the testes; and during mating the aedeagal openings are closely applied to the spermathecal openings or inserted into the spermathecal ducts. The ejaculatory pump and closed system during mating occur in many, but not all, Nematocera and perhaps throughout the Brachycera, but the tripartite condition of the organs of sperm transfer is reduced to a bipartite condition in Phlebotominae and to a ’simple’ condition, with only a single opening of the aedeagus and spermathecal system, in nearly all other Diptera. The spermathecae themselves, however, remain three in number almost throughout the order, though their ducts unite before opening; and this pattern must have been derived from the tripartite pattern of the Tanyderidae, etc., which represents the basic condition in the order.

In the Culiciformia (Culicidae, Chironomidae, Simuliidae, etc.) on the other hand, there is no ejaculatory pump but its place is taken by a wide duct lined with folded cuticle and covered by a muscular coat. The aedeagus is not suited for close apposition to the spermathecal opening. During mating a larger quantity of sperm-containing material is deposited in the surrounding atrium, as a liquid (Culicidae) or often as a spermatophore. Sperm transfer can be completed rapidly, as the pair meet in flight in the swarm. One primitive family, the Dixidae, constitutes an exception to these generalizations.

The Bibionomorpha, except for Anisopus, were not studied.

A brief comment is made on the characteristic small size of the dipterous spermatheca and the fineness of the spermathecal ducts.

Certain mayflies and stoneflies were present in a forest stream in New Brunswick after frequent yearly sprayings with DDT. Tests showed that a stonefly, Nemoura sp., apparently the most likely insect to have developed DDT tolerance, had not done so. Presence of mayflies and stoneflies in the stream was probably because they survived spraying while in the egg stage, or recovered quickly after spraying, or both.

Construction and performance of a humidity chamber, designed to provide an optimum relationship between volume and conditioning-solution surface area, are described.

Mortality of larvae of the pale apple leafroller, Pseudexentera mail (Freeman), and the winter moth, Operophtera brumata (Linnaeus), that formed cocoons and pupated in soil or vermiculite treated with pathogens was determined in orchard and insectary tests. The entomogenous fungus Metarrhizium anisopliae reduced survival to less than 5% in most tests. The entomogenous nematode DD136 was slightly less effective. The fungus Beauveria bassiana had little effect. Less than 50% of the test insects survived in non-treated media.

Three new Cryptinae (Ichneumonidae: Hymenoptera) are described from Canada: Cryptus leechi from Arctic Canada and northern Greenland, Mastrus laplantei attacking Diprionidae and Lepidoptera from coast to coast in the lumbering areas, and Medophron dytiscivorus from a Dytiscidae pupa in Ontario.

The relationship between nutrition of the host tree, Abies amabilis (Dougl.) Forbes, as influenced by nitrogen fertilizers, and the growth of populations of the balsam woolly aphid, Adelges piceae (Ratz.), was investigated. Sixty trees, growing in a greenhouse in two soil types, a nutrient-deficient mineral soil and an enriched humic soil, were infested with woolly aphid larvae. Subsequently, groups of 10 trees received foliar treatments of various concentrations of ammonium nitrate and urea. The following year, 32 young trees in Seymour Valley, B.C., were studied to determine the effect of fertilization of uninfested trees on establishment of aphid larvae.

In the greenhouse, foliar sprays of 1% ammonium nitrate solution resulted in a 23% decrease in population in 10 weeks, as contrasted with a 31% increase in the control population. In the field, larval establishment was 31% to 37% lower on the ammonium nitrate-treated trees than on the control trees. Inasmuch as there was no evidence of increased mortality of aphids in situ, we infer that the fertilizer acts primarily by inhibiting initial settling of larvae on the host trees.

Using bioclimatic chambers to provide diurnally fluctuating temperature and humidity conditions, the relationship between fecundity of females of the aphid parasite, Praon exsoletum (Nees), and different host densities, was examined over a wide range of mean temperatures. At each temperature level the number of eggs laid by females was found to vary with host density in accordance with the functional response curve (disc equation) of Holling. Superparasitism was common at all temperature levels studied, and, irrespective of host density, eggs were found laid at random with respect to hosts present. The functional response equation was thus modified so that number of hosts attacked was determined by both number of hosts present and number of eggs laid. Using this modified disc equation, the bioclimatic characteristics of parasite oviposition were examined from rhc standpoint of varying temperature levels. Oviposition was limited to mean temperatures between 8° and 29°C; near these limits the maximum number of eggs laid and the maximum number of hosts attacked were low. At medial mean temperatures (13°–24°) the number of eggs laid per parasite was high, averaging between 70 and 110 each 12-hour day. At these same medial temperatures, according to the modified disc equation, the average "handling" time per oviposition attack was shortest, and the parasite effective searching rate fastest. Averaged over a 12-hour day (this parasite does not oviposit in darkness), females of P. exsoletum were capable of laying from seven to nine eggs per hour at temperatures between 15° and 24° respectively. In all cases, the number of hosts attacked varied with numbers of eggs laid in accordance with Thompson’s superparasitism formula.

The female of Tarsonemus indoapis n. sp. is described, illustrated, and its unusual morphological features are discussed. This mite is apparently restricted to the head region, where its microhabitat is possibly the posterior tentorial pits, of the adult host, Apis indica Fabricius. It is compared briefly with other tarsonemid symbionts of bees, that is, species of Acarapis and Tarsonemus apis Rennie.

The location of types of Bruchus limbatus Horn, B. pruininus Horn, B. sordidus Horn, B. pauperculus LeConte, and B. distinguendus Horn is discussed, and lectotypes designated where needed. The confusion in American literature involving the names Bruchus obtectus Say, B. obsoletus Say, and B. distinguendus Horn is reviewed. Bruchus erythrocerus, inadvertently validated by Riley (1871), is synonymized with Meibomeus musculus (Say).

A complete list of the 29 species of fleas known from New Brunswick is presented, including several species not previously recorded and one previously undescribed species. New records are listed, with host data, for most of the species.

Progressively increasing lengths of exposure to pure nitrogen caused temporary anaesthesia, irreversible partial paralysis, and death, in that order, to the European red mite, Panonychus ulmi (Koch). The immature stages, especially eggs, were more tolerant than adult females. Confinement in 2.5% oxygen at a relative humidity approximating 100% had no effect on the mites, except on oviposition, beyond that of high humidity alone.

Extreme differences in survival of eggs of Ctenicera destructor (Brown) were observed when eggs were placed at depths ranging from 1/2 to 4 in. in the soil in the field. These differences were closely related to the soil moisture variations recorded during different seasons. Eggs that had absorbed water before being placed in the field were much more resistant to desiccation than those that had not absorbed water.

In the laboratory, eggs absorbed water, developed and hatched in soil dried to a constant moisture level of 8.2% (dry weight basis) at 98% R.H., but were unable to absorb water from soil dried to moisture equilibrium at 96.6% R.H., or from soil wetted to moisture equilibrium at 98% R.H. Some water was absorbed by eggs placed in air at 98% R.H., but this was insufficient for normal development and hatching. The soil moisture tension of soil dried to moisture equilibrium at 98% R.H. was calculated as approximately 31 atmospheres. It is evident that eggs are able to develop remarkably high internal suctions in order to absorb water from such soil.

Both the field and laboratory results showed that in drying soil, the lower limit of soil moisture at which eggs could absorb water was about 8%, considerably below the permanent wilting percentage (9.9%) of the soil used in these studies.

Current methods of sampling predator and prey populations on apple trees use two different indexes to measure the comparative abundance of each. Techniques are sought that relate the proportions of one to the other in the sampling universe (the orchard) in a quantitative manner. The most important criterion is that the sampling unit be one common to both predator and prey species and encompass representative portions of the habitat of each. The whole tree meets this criterion but it is too cumbersome to sample in toto. The large limb was, therefore, appraised for feasibility as a basic sampling unit common to many species. All clusters were counted and the predators and prey expressed as numbers per 100 clusters. The whole limb was examined for insect predators but only a representative portion of it was used in estimating mite populations. The test prey species was the European red mite, Panonychus ulmi (Koch), and the predators a small number of active insect species, mostly Diaphnocoris pellucida (Uhler) and Anthocoris musculus (Say). It was found that the numbers of mites on randomly chosen clusters from a limb were representative of the total population of mites on a limb but the associated variation was high. Samples of relatively uniform (standard) clusters of good vigour overestimated the mite population. Some other causes of variation were also examined and are discussed. A 2-year orchard test showed it was feasible to estimate the abundance of both mites and predators on a common basis and thus obtain a measure of the ratio of mites to predators in the sampling universe.

Bucculatrix canadensisella Chambers, an important defoliator of birch trees in Canada, overwinters as a cocoon in forest-floor debris. Cocoons obtained from the field over a 3-year period showed that high mortality attributable to climatic conditions could occur during this stage. Field and laboratory experiments indicated that cocoons were quite resistant to various conditions of moisture and to cold in the fall and through the winter, but that they were highly susceptible to dry conditions at the time of morphogenesis in the spring. Cool temperatures retarded adult emergence; in nature, this would expose cocoons to a prolonged period of predation. It is concluded that weather conditions during a critical period of a few weeks in late spring could greatly affect cocoon survival of this insect. Warm, moist weather would offer optimum conditions while cool and (or) dry weather would result in high mortality.

Evidence is presented for the presence of a sex attractant in female Vitula edmandsae (Packard). The ability of the virgin female to attract the male varies with age, reaching a maximum 2 days after emergence.

The pheromone-producing gland is a ring-shaped structure formed by modification of the epidermal cells in the intersegmental membrane between the eighth and ninth abdominal segments.

Peculiarities of the Bolivian fly Eurychoromyia mallea Hendel are reviewed and information on the male sex is presented for the first time. Morphological characters of the adults indicate that it is a specialized decendant of a ropalomerid-like ancestor. A lectotype is designated for the species.

Within an egg gallery of the mountain pine beetle (Dendroctonus ponderosae Hopk.) only one male is found with one female even though the virgin female or its frass may have been equally attractive to more than one male. To ascertain how the number of males joining a female is determined, a series of 10 lodgepole pine rearing slabs and 10 observational plates (Reid 1962) were infested with virgin mountain pine beetle females. The females were allowed 1 day to become established prior to the experiments. On the second day one virgin male was placed in each gallery. The next day a second was placed near the entrance to the gallery and its behavior was noted, as well as that of the first male.

Ips calligraphus (Germar) is distributed continentally throughout North America, including Guatemala and British Honduras. It has been collected on only rare occasions in California, primarily in the central Sierra Nevada Mountains. Four generations were observed during 1961 and 1962, and average summer development required about 40 days. All stages except the egg were observed in the winter. The unique gallery system exhibits four to six egg galleries, which range in length from 25.4 to 38.1 cm, and radiate characteristically from a large, irregular, nuptial chamber excavated by the male. At Grass Valley, Cal., this bark beetle was observed breeding predominantly in the thick-barked portions of the lower bole. Its galleries are often intermixed with those of Dendroctonus brevicomis LeConte, I. confusus LeConte, I. latidens LeConte, and Melanophila californica Van Dyke in ponderosa pine. I. confusus was the most abundant species of Ips in all localities where I. calligraphus was found.

This review of the tribe Xyleborini (Coleoptera: Scolytidae) includes two genera, Xyleborus Eichhoff, with 17 species, and Xylosandrus Reitter, containing 3 species. All species are described and most are illustrated. Keys for the separation of the genera and species are provided. Distributional and biological data are given. New combinations are: Xyleborus obliquus (Leconte) (= Pityophthorus obliquus Leconte); X. lecontei (Hopkins) (= Ambrosiodmus lecontei Hopkins), and X. sayi (Hopkins) (= Anisandrus sayi Hopkins). New synonymies are: Xyleborus obliquus (Leconte) (= Ambrosiodmus linderae Hopkins); X. obesus Leconte (= Anisandrus populi Swaine); X. ferrugineus (Fabricius) (= X. retusicollis Zimmerman and X. soltaui Hopkins); X. xylographus (Say) (= X. inermis Eichhoff and X. planicollis Zimmerman); X. volvulus (Fabricius) (= X. schwarzi Hopkins and X. rileyi Hopkins), and X. howardi Hopkins (= X. fitchi Hopkins). A Japanese species, X. rubricollis Eichhoff, is reported from the United States for the first time. A neotype is designated for X. xylographus (Say).