Field, glasshouse, and laboratory tests showed that deposits of polyhedra of the nuclear polyhedrosis virus of the cabbage looper, Trichoplusia ni (Hübner), on foliage are practically non-infective after a 1-month exposure to weathering. Inactivation by sunlight appeared to be more important than removal by washing by rain in causing this loss of activity. The virus was readily inactivated by exposure to ultraviolet light. Virus exposed in aqueous suspensions of polyhedra or in wetted deposits was inactivated by shorter exposures than was virus in dry deposits of polyhedra.

A key and measurements are presented for the eggs of 23 species of Aedes. Twenty species from California and Nevada are illustrated, and eleven previously undescribed eggs are described.

Lyctocoris canadensis new species is described from southwestern Quebec. The other species of Lyctocoris known to occur in North America are L. campestris (Fabricius), L. doris Van Duzee, L. elongatus (Reuter), L. mexicanus Kelton, L. okanaganus Kelton & Anderson, L. rostratus Kelton & Anderson, L. stalii (Reuter), and L. tuberosus Kelton & Anderson. Species are keyed, known information on their ecology is given, and male genitalia and female abdominal segments are illustrated.

At least seven species of arthropods were found in or associated with leaf galls of the grape phylloxera, Phylloxera vitifoliae (Fitch), on cultivated and wild grapes in Ontario, Leucopis simplex Loew and Lestodiplosis grassator (Fyles) were the most common species. Larvae of both preyed upon eggs of the phylloxera; whether they attacked other stages was not determined, nor was their effect on gall populations. L. grassator occurred almost exclusively on wild grapes; L. simplex was found in galls on both cultivated and wild grapes, associated with all generations of the leaf form of phylloxera. L. simplex was parasitized by Melanips sp. and Lygocerus sp. Another predator, Scymnus cervicalis Muls., occurred rarely. Thrips, mites, and neuropterous larvae were also found occasionally, but predation by these species was not demonstrated.

The viral activity of soil treated with polyhedra of the cabbage looper, Trichoplusia ni (Hübner), was determined at intervals by bioassay. Soil in plots treated in 1961 at a rate of 6.4 × 1010 polyhedra per square meter of surface contained about 25% of the original infective virus more than 5 years after treatment. A similar rate of decline in viral activity occurred in plots treated with polyhedra in 1963. Viral activity of soil retained under artificial conditions decreased more rapidly.

Field and laboratory tests showed that foliage of cruciferous plants grown in soil treated with polyhedra was contaminated with the virus, probably largely by virus-laden soil being splashed onto foliage by rain.

The winter moth, Operophtera brumata (L.), a recent introduction to North America, is a serious pest of apple in Nova Scotia. Natural controls, mainly the parasite Cyzenis albicans (Fall.), reduce its rate of increase, and selective chemical controls are applied to maintain economic levels. Its maximum density is limited by its food supply in neglected orchards. The mean freezing point of O. brumata winter eggs is −31°F. Egg mortality increases appreciably with increase of duration of exposure to low temperatures in the −26°F to −34°F vulnerable range. It seems probable that winter moth will continue to spread slowly over much of Eastern North America.

Prepupae of Neodiprion sertifer (Geoff.) held in darkness at 21 °C undergo a short normal diapause if exposed as feeding larvae to long photoperiods, but have no diapause if reared in the larval stage under short photoperiods. If cocoons from short-day rearings are exposed to 10 °C instead of 21 °C, a small proportion of the prepupal larvae undergo the normal or short diapause, but the majority enter an intense or prolonged type of diapause which results in three clearly defined periods of adult emergence within the range of 160 to 800 days after cocoon spinning. Mortality increases directly with the prolonged cocoon periods associated with intense diapause at 10 °C and there is a progressive decrease in reproductive potential of the survivors. If cocoons are held at 29 °C normal diapause and morphogenesis are prolonged but there is no evidence that a state of intense diapause is induced. Mortality is extreme, however, and the reproductive potential of the survivors is greatly reduced.

The implication of these findings is discussed in relation to prolonged diapause in nature, a factor critical to the assessment of the seasonal history and population dynamics of the insect.

Male Grapholitha molesta (Busck) treated with 40 krad of gamma radiation in the late pupal stage reduced egg-hatch by 93.6%, and in the young adult stage by 96.4%, in eggs from untreated virgin females with which they were mated; in addition, hatched larvae failed to complete development. Induced sterility was consistently greater in treated adults as compared with treated pupae. Females in the late pupal stage were sterilized with about 10 krad.

Male longevity decreased in proportion to the radiation dosage above 30 krad when caged at a ratio of 3 ♂: 1 ♀. Longevity of untreated males decreased in proportion to the number of females available for mating.

Radiation levels of 30 krad or more decreased male mating, especially when applied to the pupal stage, in inverse proportion to dosage, as detected by caging males with three times as many females.

The number of matings per untreated male increased with the number of females available up to an average of 3.8 while the number of matings per female averaged approximately 1.6 with from one to three males per female.

A model is presented which describes the effect of sterile male release on a wild population. This model is not subject to restrictions, such as equal competitiveness between normal and sterile males and sperm nor to insect species whose females mate only once. The model is an approximation as it assumes constancy in several dynamic population variables. However, it has application in determining the approximate effects of sterile male release and in decisions on the number of sterile males required for release programs. It also has uses in ecological research.

Females of Scambus buolianae did not lay eggs when deprived of food in the form of host tissues throughout adult life. Greatest egg-production and longest life resulted when that food was continuously available. Average egg-production was reduced to under one-third, and longevity reduced to two-thirds or one-half, in females that were permitted to feed on host body fluids only intermittently or that were deprived of them after the first 15 days of adult life. No eggs were laid by females deprived for the first 20 days, and longevity was reduced to one-third. However, absence of host body fluid as food during the first 15 days only did not significantly reduce egg-production or length of life. Tests showed females of S. buolianae have distinct and similar relative preferences for different host species as sources of body tissues for food. Both sexes showed distinct and similar preferences for species of wild flowers as sources of carbohydrate. The results support earlier findings and show that the presence or absence of suitable foods for the adults may determine whether or not an introduced parasite can establish itself, and can influence the effectiveness of existing parasites as biological control agents.

Detailed descriptions and illustrations are given for the immature stages (egg, larva, prepupa, and pupa) of Stenodynerus claremontensis (Cameron), a solitary ground-nesting vespid wasp from the western United States. Special attention is given characteristics which may be used to separate the four larval instars.

Females of I. conquisitor could not be conditioned to attack horizontal tubes instead of vertical tubes of the same size and probably cannot distinguish between them. I. conquisitor could be conditioned to attack tubes of particular lengths or diameters and tubes mounted on pins rather than on plastic forms. These results are interpreted as showing that the parasites can recognize these differences in the host shelter and that these characteristics could influence host selection. It is suggested that if a polyphagous parasite to be introduced against a particular pest is first conditioned to that host in pieces of its host plant, the success of the parasite in finding that host and hence its chances of establishment would be increased.

The flying season (sensu lato) and emergence period of Anax junius Drury were determined by routine counts of adults and exuvial collections at a small woodland pond m northern Illinois. The flying season, in this case including activity of apparently young adults, was from April to mid-November. Emergence listed 55 days (26 August to 19 October 1965), the pattern being of the "summer" species type. Before emergence began all adults appeared to be mature and oviposition was often seen. After emergence began, apparently young adults predominated and no oviposition was seen.

The cabbage maggot, Hylemya brassicae, has a facultative diapause induced by the appropriate conditions of light and temperature: 16 hours of light per 24 hours at 20 °C produce nondiapause pupae while 12 hours of light per 24 hours at 20 °C produce diapause pupae. Diapause can be terminated if the pupae are exposed to temperatures from 0 to 5 °C for 4–5 months. Discrepancies in the literature with regard to the foregoing facts are explained.

A new species of Dirophanes parasitic on Choristoneura pinus Free. is described in comparison with its closest relative D. spinicoxus Viereck and a species it superficially resembles, Phaeogenes cacoeciae Viereck. A key to the three species is included.

Two braconids, Opius lectus Gah. and O. alloeus Mues., are being reported for the first time in Quebec as parasites of the apple maggot, Rhagoletis pomonella (Walsh).