Sterilization of male and female Ips confusus (Coleoptera: Scolytidae) exposed to gamma radiation (Co60) as newly emerged adults was almost complete at levels exceeding 7500 r and 10,000 r, respectively. Mating behavior of males as expressed by sperm transfer was unaffected by dosages up to 60,000 r. The capacity of beetles of either sex to establish galleries was not affected significantly below this dosage, but female gallery pattern was altered above 15,000 r. Longevity was reduced at levels greater than 5000 r. LD50 for males occurred at 11.5 days at 7500 r and 29 days in the controls. Mortality of progeny resulting from males irradiated at substerilization levels was higher than in the controls. The dosage to achieve significant population reduction with minimum effect on longevity and other biological activity is estimated to lie between 6000 and 7500 r.

These studies indicate that this sterilization technique may have promise in the control of bark beetles. The necessity for rearing large numbers on artificial media could be circumvented by mass trapping utilizing their natural sex attractant and by mass rearing in cut host material in the laboratory.

Three genera of Odonata, Epitheca, Tetragoneuria and Epicordulia, have previously been regarded as distinct. Analysis of adult characters, especially the venation and habit of oviposition, shows them to be congeneric, the name Epitheca being appropriate for the resulting combination. Larval morphology is consistent with this grouping.

A list is given of a total of 82 species of animals, mainly insects and mites, taken from the bracket fungus Polyporus betulinus (Bull.) Fr., growing on dead birch in Gatineau Park, Quebec.

Ovarian development and egg production in the larch sawfly, Pristiphora erichsonii (Hartig), were studied in the development of a method for measuring reproductive capacity for population studies. Most of the oöcytes are mature at the time of adult emergence but some mature in the following few days. Quantitative differences in foliage consumption during the larval stages have an appreciable effect on egg production but normal environmental temperature differences and exposure to flooding during the spring development period influence ovarian development only to a limited extent.

Reproductive capacity can be determined by oöcyte counts of dissected adults of uniform age. The sample size necessary for estimates of various degrees of precision was calculated.

Several size measurements have a significant correlation with the numbers of oöcytes produced. The regression of numbers of oöcytes on adult weight is of limited usefulness in the estimation of reproductive capacity. This is largely due to the individual variability in the extent to which fat body tissue is utilized in ovarian development particularly in the case of the larger adults.

First instars of 93 North American species of mosquitoes are studied and 56 are illustrated, 41 for the first time. Generic differences are well marked in this instar and nearly all species are separable.

Two keys to the 11 North American genera are presented; the first is constructed to show similarities between first and later instars. Each genus is described and keyed to species, and notes are given on each species. A supplementary key to the species of the southeastern states is designed for the use of a binocular microscope with magnification up to 60 ×.

Specific and generic differences are as well marked in the first as in the fourth instar. Identifications are as easy or as difficult in the first as in the fourth instar, though usually based on different characters.

An expanded key to the North American species of Aedes, incorporating those previously treated by Bohart and by Price, is attempted. The key reveals several species complexes which have not been discerned from other stages of the life cycle, namely, Aedes canadensis, nigromaculis, punctor, stimulans infirmatus and trivittatus.

A key to the first instars of the 37 species of the world-wide Anophelinae is presented, on the basis of published descriptions and figures of the exotic species.

The Eleticinae are an archaic and in many respects primitive group of Meloidae found in South America (widespread), Africa (south of the Sahara Desert), and the Oriental Region (India to Thailand). They are, in general, poorly represented in collections, and very little is known definitely of their bionomics. On the basis of an analysis of adult anatomical characters the subfamily is defined in detail and is classified to the generic level in the present paper. Two tribes, seven subtribes, and 10 genera are recognized, keyed, and diagnosed. The tribe Spasticini is arranged as follows: Protomeloina Abdullah, transferred from the Meloinae and reduced to subtribal rank, with Protomeloe Abdullah; Spasticina Kaszab with Spastica Lacordaire; Xenospastina, new subtribe, with Xenospasta, new genus; and Anthicoxenina, new subtribe, with Anthicoxenus Fairmaire and Germain, formerly placed in the Anthicidae, and Iselma Haag-Rutenberg. The arrangement of the tribe Eleticini is: Eospastina, new subtribe, with Eospasta, new genus, and Serrospasta, new genus; Eleticina Wellman with Eletica Lacordaire (and including, as subgenera, Sibuteletica Pic, Meteletica Kaszab, and Proeletica Kaszab); and Ertlianina, new name for Ertliini Kaszab, with Ertliana Selander (= Steniselma Borchmann, new synonymy) and Ceriselma Borchmann, the latter elevated from subgeneric rank in Iselma. Species described as new are Protomeloe simplex (Argentina), Spastica minas (Brazil), Xenospasta flava (Colombia), and Serrospasta vittata (Colombia).

Intensive studies on the biology of the spruce needle-miner, Pulicalvaria piceaella (Kft.), were carried out in the Province of Quebec between 1956 and 1959. The cycle is univoltine, larvae have five instars, and the insect overwinters in the larval stage. P. piceaella collected from the Gaspé Peninsula were significantly larger than those from southwestern Quebec, which in turn were larger than individuals from an incidental collection made near Syracuse, New York.

Young larvae were most often found in foliage damaged by associated defoliating insects. In these circumstances, they mined needles adjacent to the damaged sites or fed partly on the damaged material and partly by mining needles, and in some cases fed exclusively on the dead foliage. The majority of larvae entered dormancy about the third week of September in all localities and in all years, an apparent diapause reaction to a critical photoperiod of approximately 12 hours. Resumption of feeding activity the following spring was apparently governed by temperature. In the spring, larvae transferred to new feeding sites, either to the current year's buds or to the previous year's foliage. In the Gaspé Peninsula the larvae migrated to buds, whereas in southwestern Quebec reinitiation of larval activity preceded the opening of the buds by almost a month, and larvae transferred to new sites on the previous year's growth where they mined needles. Pupae were often found in silken cells within the various feeding sites but most larvae probably dropped to the soil to pupate.

Mating and oviposition habits of the moths are described. Mean fecundity was 22 as derived from dissections of gravid females, and mean number of eggs deposited per female averaged 11. Eggs were deposited singly and usually found in the same sites as young larvae.

Factors which influence the rate at which Philodromus rufus Walckenaer attacks prey are discussed. Drosophila melanogaster Meign. was used as prey throughout the rearing and testing of P. rufus. Spiders used in these tests were immature at the time of capture and reared to the adult stage in the laboratory. Feeding histories were maintained for all spiders, although the experiments designed to measure the attack response of individual spiders to changing prey density were done with adult males.

In the immature stage there was no difference between the feeding rate of male and female spiders. The adult males, however, were relatively inefficient predators; females killed approximately six times as many flies in their adult lives as males. The irregular feeding pattern of the females, as compared to the fairly uniform feeding pattern of the males, resulted in the males being more amenable to experimental tests. Periods of starvation, molting, and opposition strongly influenced the feeding rate of P. rufus. At high prey densities there was an inverse relationship between hunger and utilization of individual prey. This resulted from uncaptured prey interfering with the feeding spider.

Both feeding time and searching time showed a relationship to prey density. Individual fly activity increased with fly density and this resulted in a functional response curve with an increasing slope. One of the basic requirements for regulation was thereby demonstrated. When prey density was corrected for the increase in fly activity by computing a new density estimate based on fly activity, a typical functional response for invertebrates became evident for hungry spiders but not for well-fed spiders. By using Holling's “disc equation” the difference between starved and satiated spiders was explained as an interaction between prey and predator characteristics. Owing to density-dependent parameters such as prey activity, predator feeding time, and “rate of discovery”, no known mathematical model fitted the data.

The role that nutrition plays in biological control may be seen in natural environments; but to understand and to make use of this role the principles concerned must be understood essentially in terms of specific chemical substances. A number of principles of insect nutrition particularly relevant to biological control concern the food of the host, the host itself, and its parasitoid. These principles may be generalized into three laws and they are called here the rule of sameness, the principle of nutrient proportionality, and the principle of cooperating supplements. Each is discussed in connection with its application in the laboratory or in natural environments, and a few examples of work relating to each are given. Most examples quoted are from work at Belleville, Ontario, on the parasitoid Pseudosarcophaga affinis Auct. nec. Fallén.

Species replacement is most commonly observed among the parasitic Hymenoptera because of their dominance in biological control. Such replacement is necessarily a reproduction phenomenon involving interspecific competition in population-saturated areas. The competitive interactions of parasitic populations are differentiated into two types, “intrinsic” and “extrinsic”, with characteristic conditions and mechanisms.

Intrinsic competition consists of interference between individuals of the interacting populations, being manifested by such factors as cannibalism, mutilation, starvation, suffocation, production of toxic or repellent excretions and secretions, and the differential susceptibility of individual hosts to parasitic attack.

Extrinsic competition concerns the interaction of populations as groups and is manifested largely by host-habitat finding, host-finding, and host acceptance.

Replacement through intrinsic competition takes place regardless of host abundance; replacement by extrinsic competition is an effect of decreased host abundance.

New species of Ablautus Loew described are arnaudi from Baja California and California, basini from California and Nevada, colei from Washington and Oregon, and coachellus, linsleyi and schlingeri from California; females of californicus and vanduzeei are described; and a key to the species is given. New species of Omniablautus Pritchard described are nigripes and tolandi from California; Ablautus rubens Coquillet and A. nigronotum Wilcox are transferred to Omniablautus; and a key to the species is given.

Pansy spot, a discoloration of the skin of McIntosh and Spartan apples, was shown to be a reaction of the apples to the egg punctures of thrips. Periodic sampling of apple blossoms and native hosts associated with apple orchards showed that Frankliniella occidentalis (Pergande) was the dominant species. The adult thrips moved from host to host as each came into flower, and apples were but one of several hosts attacked during the early spring.

The thrips were most numerous in apple blossoms during the bloom period, and oviposited in the flower parts. The adult thrips left the apples after the bloom period, and the nymphs that hatched from the eggs developed in the calyx end of the young fruit. When the nymphs matured they oviposited in the young apple before leaving for other hosts. The area of apple skin surrounding the thrips egg developed the typical pansy spot symptoms. Other apple varieties were also attacked, but did not develop pansy spots.

It was evident that the best time to apply control measures was at the petal fall period, when nymphal thrips were present but before damage was caused to the young apples.

Eggs of Ctenicera destructor (Brown), Ctenicera aeripennis (Kirby) and bisexual and parthenogenetic strains of Hypolithus bicolor Eschscholtz must absorb water to complete embryonic development.

In eggs of C. destructor incubated at 24.4 ± 0.5 °C. in sifted soil containing 15% water (wet weight basis), water absorption started during the second day of development and ended within 24 hours. The mean wet weight increased from 26.6 ± 0.2 (standard deviation) μg. to 39.2 ± 0.6 μg. by the third day. During this period the water content increased from 42% to 64%. After the third day, the mean wet weight remained constant but a significant increase (P < 0.01) in the mean water content and a significant decrease (P < 0.01) in the mean dry weight occurred.

The progress of water absorption in eggs of C. aeripennis and the two strains of H. bicolor was similar to that in C. destructor. Differences from C. destructor were apparent, however, in the sizes of the eggs, in the initial and final amounts of dry matter and in the water contents.

Water absorption by eggs of C. destructor started after one day of incubation at 25 ± 0.5 °C., after 1 to 2 days at 20°, and after 4 days at 15°. The rate of absorption appeared to be slightly more rapid at higher temperatures within the range of 15–25 °C.

From the revised list of the Lepidoptera of Greenland and from recent work in Ellesmere Island it is shown that almost all the species found in high arctic Canada occur also in Greenland, predominantly in the north, and that this high arctic element constitutes a large fraction of the fauna of Greenland as a whole. It is suggested that this part of the fauna originated entirely from the nearctic by the little-interrupted land route across the arctic islands. The poverty of southerly Lepidoptera in Greenland stands in sharp contrast. It is illustrated by a comparison with the vascular plants and by other comparisons with the Lepidoptera found in the corresponding life zones in North America, and this section of the paper includes the first published list of the Lepidoptera of Baffin Island. It is suggested that this southerly fauna is of adventitious origin, by casual dispersal from overseas (Labrador, Iceland) or perhaps in a few cases by introduction by man. Thus Greenland, in respect of its fauna of southerly type, is an oceanic island of post-glacial age. Similar evidence suggests that Iceland also has been populated mainly in the same way. The conclusions derived from the Lepidoptera apply to several other groups of insects and also to the mammals, including man.

The factors influencing oviposition and feeding of Enoclerus lecontei, and the effect of temperature on egg development and survival, were studied in the laboratory.

When food was not a limiting factor, the total number of eggs laid, and the total number of bark beetles consumed by clerid pairs during their lives was strongly influenced by longevity of the female and to a lesser extent by female “vigor”. Female “vigor” and longevity were not necessarily coincident. The rate of oviposition and the rate of food consumption are mainly influenced by the “vigor” of the female clerid.

The effect of suboptimal food on oviposition was determined. Regression equations are given for estimating the number of eggs laid utilizing three measures of food supply, number of bark beetles supplied, their weight, and number eaten. The independent variables may be used separately or combined as a multiple regression.

Time for egg development varied from 5 days at 35 °C. to 28 days at 15 °C. Optimal conditions for development and survival were between 20° and 25 °C. Eggs can withstand cold storage (7° to 9 °C.) for 10 days before survival is impaired. Thereafter, mortality increases logarithmically until the 100 percentile is reached at about 43 days.

The quinoxalines, Eradex and Morestan, were found to be very effective miticides in laboratory and orchard experiments with the latter the most toxic. Applied at the pink stage of apple bud development Eradex and Morestan gave excellent control of European red mite, Panonychus ulmi (Koch), and delayed the build-up of the apple rust mite, Vasates schlechtendali (Nal.), and the McDaniel spider mite, Tetranychus mcdanieli McG. Both miticides were also very effective when applied in summer. The rates of use for Morestan were established at 8 to 16 ounces of active ingredient per acre in concentrate sprayers and at 2 ounces per 100 gallons in handgun sprayers and at twice these rates for Eradex. Where Eradex or Morestan were the only miticides used in an orchard for four years, the control of the European red mite and the McDaniel spider mite was excellent, an indication that selection of a resistant strain had not occurred. Morestan was highly toxic to the predaceous phytoseiid mite, Neoseiulus caudiglans (Schuster). Morestan has not injured fruit or foliage when applied at the pink bud stage but has marked fruit when applied in summer especially when applied by high-volume handgun sprayer.

The faunal changes in the crown stratum of a newly established red pine plantation were observed during the first five years of growth. The crown faunae of three older stands planted in 1950, 1939, and 1929 were sampled throughout the growing seasons of four consecutive years by a technique employing pyrethrum insecticide.

The stands represent four stages in the development of a red pine community over a period of 35 years, and the presence, distribution, density, annual and seasonal fluctuations, species succession, and food relations of arthropod taxa are discussed.

Species colonizing trees in the establishment stage are largely replaced in the transition stage by a species-complex that persists throughout the succeeding monoculture and young-forest stages. Arthropod density in relation to crown size increases rapidly until the trees are about 15 years of age, and then declines. The pattern of seasonal abundance is dominated by a few species. The ratio between parasite–predator and prey species remains remarkably stable throughout the three older stages of the community.

The haemocytes of adults of the stonefly, Acroneuria arenosa Pictet, are described and figured as they appear in vivo in the wings and as fixed and stained elements in blood films prepared in four different ways. The adequacy of the blood films is judged by comparing the haemocytes there with those in vivo, and the cell complex is interpreted from both aspects. Four categories of haemocytes, the prohaemocytes, plasmatocytes, granular haemocytes, and hyaline haemocytes, are denoted and characterized within these visual limits. The validity of one category, the hyaline haemocytes, is questioned on the basis of cell counts and cell morphology but is tentatively retained. Variations in the haemocyte complex during the adult life is considered. The progressive decrease in relative numbers of circulating plasmatocytes with age is shown to be due to their adherence to the walls of wing veins and presumably to other tissues within the body.

Diel patterns of emergence, flight, host-seeking and oviposition have been studied in two mosquitoes, Aedes (Ochlerotatus) impiger and A. (O.) nigripes, at Hazen Camp (71° 18′ W., 81° 49′ N.). Diel periodicities were detected in both species for all these activities except flight. Oviposition of A. nigripes shows a well-defined pattern, but otherwise periodicities are evident only as slight and somewhat irregular diel fluctuations. All diel patterns show a maximum near solar noon, and appear to result from a direct (exogenous) response to ambient temperature. The patterns of host-seeking flight, closely similar in both species, are compared with those recorded for Aedes (Ochlerotatus) at lower latitudes. Small morning and afternoon peaks at Hazen Camp are seen as vestiges of sunrise and sunset maxima that characterize this periodicity further south.