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.

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.

Emergence in the laboratory at 80°F. of apple maggot adults from pupae overwintering outdoors was compared at different times of the dormant period and with emergence from pupae stored at 37-40° for all or varying parts of the dormant period. Shorter incubation times were required for emergence when pupae from outdoors were placed in incubation in autumn, one to three months after larval maturity, than during winter or early spring. Exposure for at least six weeks to low temperatures, either outdoors or in the laboratory, at first increased the incubation time required for emergence. Later the required incubation times of insects overwintering outdoors or in the refrigerator decreased as the duration of exposure to low temperature (or duration of dormancy) increased. But no such decrease was evident in samples of pupae held at 37-40°F. for periods longer than six months. Comparison of emergence from pupae from outdoors with those stored at 37-40°F. when incubated in spring and early summer showed that outdoor temperatures before June 1, in 1959-61 at least, had no effect on the subsequent emergence from pupae overwintering outdoors. When incubation at 70°, 75°, 80°, 85° and 90°F. was compared, the times required for emergence decreased with increased incubation temperature up to 85°F. However incubation at 90°F. resulted in a decrease in the percentage of incubated insects that emerged as adults.

The immature stages of five Canadian species of Pero Herrich-Schaeffer are described. These species arc P. bebrensarius Packard, P. bonestarim Walker, P. mizon Ritidge, P. morrisonaius Henry Edwards, and P. occidentalis pnckardi Cassino and Swett. Three colour patterns have been noted in the larvae of P. mizon and P. morrisovarius but only nne in each of P. behreniarius, P. bonestarius and P. occidtmtalis packardi. Brief accounts of the life histories and habits of the species are presented together with a key to the mature larvae.

The midge Contarinia washnigtonensis Johnson is capable of causing serious seed loss in Douglas-fir in British Columbia, Washington and Oregon. The female lays its eggs from late May until early July in the young cones. When the eggs hatch larvae feed in the cone scales, sometimes causing direct damage to seeds and often killing scales before cone maturity. When larvae have completed feeding they leave the cone scales in late summer and autumn to drop to the ground where they spin cocoons and remain overwinter in the litter.

The genus Hoploseius is redefined on the basis of H. cometa (Berlese), H. drosophili (Chant) new combination, and H. bakeri new species, which are described, keyed, and illustrated. Fragmentary ecological data with specimens of Hoploseius make it apparent that the mites are associated with polyporous bracket fungi and have a phoretic relationship with adult drosophilid flies.

Litoleptis alaskensis, a new genus and species from Alaska, and Bolbomyia melanderi, a new species from the Appalachians, are described. Cekendia wuorentausi is redescribed, and the genus synonymyzed with Bolbomyia. Further records of the Nearctic species of Bolbomyia are given. A generic group composed of Hilarimorpha, Litoleptis, Bolbomyia, Archicera and Austroleptis is proposed.

Inoculative freezing of insects is distinguished from nucleative freezing and is treated from the standpoint of the delays observed in freezing. On the assumption that the fine structure of the cuticle regulates the penetration or growth of external ice into the insect's body, the cuticle was experimentally altered by soaking, boiling, and immersion in strong detergent solution. Soaking was of doubtful effectiveness, whereas boiling and detergent hastened inoculation, Detergent also caused many insects to freeze when the contact water froze, with no delay. Rate of inoculation of untreated larvae was directly proportional to the area in contact with ice, and inversely proportional to temperature down to −10 °C. No further rate increase took place down to −15 °C, possibly because the vapor pressure difference between ice and supercooled body fluid does not change appreciably in this temperature range. Larvae froze more rapidly when they had already been frozen and thawed once or twice. No relation between inoculation rate and rate of water loss in a dry atmosphere could be established.

The freezing of water in extremely small spaces is discussed and related to the process of inoculative freezing. Probable pathways of ice growth through the cuticle are considered in relation to known structural characteristics and the results of the present experiments. Two hypotheses are proposed to account for the observed delays in freezing, but neither is wholly satisfactory. The first postulates that the outer extremities of the pathways, through the epicuticle, are hydrophobic and contain air which temporarily separates contact moisture from pore liquids. After freezing of the contact moisture a vapor pressure differential results in a net flow of vapor outwards, the vapor freezing on the ice and building inwards until the ice front touches liquid in a space large enough to allow freezing. This hypothesis assumes the existence of at least one pathway large enough to support ice penetration without hindrance caused by restricted size. The second hypothesis assumes that no such unrestricted pathways are present, all being inadequate in size. Differences in chemical potential between ice and liquid cause pore liquids to move outwards to the contacting ice surface and accrete on its

North American Ips of Group II (Hopping, 196îb) are I. emarginatus (Leconre) and I. knattsi Swaine. They are the only Ips having the third declivital spine emarginate ar the tip. They breed in various species of pine. The distribution of I. emarginatus is from southern British Columbia to California and eastward to Montana. I. knausi is found in Colorado, New Mexico and Arizona. A key to the species is given. I. plastographus (Leconte) is the sole representative of Group III. It is the only four-spined Ips with the sutures of the autennal club strongly angled at the middle. I. plastographus breeds in species of pine. It occurs from southern British Columbia southward in the western United States and through Mexico into Guatemala. Hosts and more detailed distributions are given for species in Groups IT and III.

Each of the three grasshopper species, Camnula pellucida, Melanoplus bilituratus and M. bivittatus, spent approximately 13, 17, 19, 22 and 29% of total time in nymphal development in the successive five instars. These proportions appeared similar at each of the six rearing temperatures 75, 80, 85, 90, 95 and 100°F. The times required for total nymphal development at these temperatures were 53, 36, 28½, 23½, 18 and 17 days, respectively. It was estimated that, for the grasshoppers to complete nymphal development and attain sexual maturity in time to have a reasonably good chance of successful reproduction, their integrated temperature experience for 12-hour days should be not less than 95°F. Whereas the apparent mid-point of nymphal development in terms of morphogenesis is midway through the third instar in the typical five-instar grasshoppers, the midpoint of time spent at constant temperatures is near the end of the third instar. C. pellucida appears unable to complete nymphal development at a temperature as low as 75°F.; the Melanoplus species, however, can complete development at this temperature, but with reduced survival.

Northern and southern specimens of the fall webworm in eastern North America exhibit color differences in both the adult and larval stages, and have often been referred to Hyphantria textor Harris and H. cunea Drury, respectively. However, they will readily inter-breed and produce viable offspring; differences in wing maculation are not discrete and genitalic differences have not been found; differences in the degree of larval pigmentation are not discrete and depend largely on environmental factors; and the nesting and feeding behaviors are similar. It is therefore concluded that the common webworm (larvae with the head and dorsal tubercles black) in both north and south should be referred to H. cunea, which has priority. A sibling species or race (lighter heads and tubercles and different nesting and feeding habits) occurs sympatrically with cunea in the south and also, rarely, in the north; if it has specific status it cannot be referred to either cunea or textor; so textor is relegated to synonymy.

Blood-sucking horse flies and deer flies of the family Tabanidae are important pests of livestock and man in Hastings County, Ontario. In a survey made during 1951-56, immatures of 29 species were collected and reared to obtain information on their insect parasites and other biotic control agents in different habitats. Most of the tabanid specimens were found at five sites where populations were high. The periods of pupation and emergence of Chrysops and of the larger tabanids are shown. The most numerous biotic agents found were two egg parasites, Trichogramma minutum Riley and Telenomus emersoni Girault. Parasites of the larva were a tachinid, Phorostoma novaeangliae (West) and Bathymermis sp., a nematode parasite of Chrysops spp. There were two pupal parasites: Diglochis occidentalis (Ashm.) (Pteromalidae) and Trichopria sp., probably tabanivora Fouts (Diapriidae). There is evidence that both these parasites attack the mature larva of the host.