The numbers of heat units during a fixed overwintering period and a shifting early larval feeding period for the forest tent caterpillar, Malacosoma disstria Hübner, were calculated from daily temperature data and related to known infestations of this insect in the Prairie Provinces and Ontario. Paired comparisons showed that years with increasing populations had cooler overwintering periods and warmer early feeding periods than did those with decreasing populations. Continuous records for each of 10 climatological stations showed that all known infestations in these areas were preceded by a single year (2 to 4 years earlier) with a relatively cool winter and an unusually warm spring, and that most population collapses were accompanied by cool springs and some by warm winters. The same general pattern prevailed for infestations in southern Ontario, when compared with the numbers of heat units at Toronto for the period 1860 to 1969. Some of the assumptions made during the analyses and the possible use of the results in predicting when and where outbreaks are likely to occur are discussed.

Stator vachelliae new species is described from Texas, Mexico, El Salvador, and Venezuela and S. mexicanus new species is described from San Luis Potosi, Mexico. Stator usticolor (Sharp) and S. semicolon (Sharp) NEW COMBINATIONS have been determined as belonging to the sordidus complex. The following rearing records are recorded: S. vachelliae and S. subaeneus (Schaeffer) from Acacia farnesiana and S. mexicanus from Acacia cornigera.

Surveys, from 1948 to 1964, showed that parasites were of minor importance in controlling the European corn borer, Ostrinia nubilalis (Hübner), in extreme southwestern Ontario. Of the three species that became established, Lydella grisescens Robineau-Desvoidy was the most widespread and the most important. Eriborus terebrans (Gravenhorst) showed considerable buildup in parts of Essex County after discovery there in 1957, and Sympiesis viridula (Thomson) was found widely dispersed, but low in density, throughout the survey area. There is an indication that parasites might be of greater importance in areas where the second-generation borer is increasing.

The morphology of the stylets of the six-spotted leafhopper, Macrosteles fascifrons (Stål), is described from light and transmission electron microscopy. The maxillary stylets are about 1/5 longer than the mandibular stylets. Both pairs of stylets contain central ducts running from their bases to their tips. The duct in the mandibular stylet is unbranched but that in the maxillary stylet bifurcates midway toward the tip. The mandibular duct contains 3 dendrites; the maxillary duct contains 5 dendrites. The fine structure of the dendrites is described.

Two new species, Micropeplus volcanus from Mexico and M. smetanai from British Columbia, are described and illustrated. New distributional and habitat data are given for nine other species of the subfamily. The male genitalia of Kalissus nitidus Leconte and Peplomicrus acumen (Sharp) are illustrated for the first time. A revised key to the New World species of the genus Micropeplus is presented.

Melanotus communis (Gyllenhal) larvae were introduced into temperature gradient columns containing moist or dry organic soil. In other experiments certain sections of the columns contained moist soil while soil in the remaining sections was dry.

Moist soil caused M. communis larvae to aggregate at higher temperature levels (24 °C) whereas dry soil evoked a positive response to the coolest level (10 °C). Cool (10 °C), moist sections attracted most of the wireworms while sections containing moisture at the highest temperature level caused a bimodal pattern of aggregation with M. communis larvae moving to both cool–dry or hot–moist conditions.

Differences in geotactic responses by M. communis larvae did not occur when the column was positioned vertically or horizontally.

Winthemia occidentis Rhn. was introduced into Newfoundland to strengthen the parasite complex of the eastern hemlock looper. This tachinid has two emergence periods, one in the fall, the other in the following spring. A method was developed for rearing overwintering tachinid larvae to the adult stage. The best rearing results were obtained when the larvae were stored outdoors in jars of peat moss for the fall and winter period and removed to controlled temperature and humidity conditions in the spring, to complete development.

The strong attractiveness of logs infested with female ambrosia beetles, Trypodendron lineatum (Oliv.), to the flying population was sharply reduced after the addition of males. The field response of T. lineatum was greatly reduced when air from logs infested with attractive females was mixed with air passing over logs infested with both sexes. The findings suggest that females keep producing the attracting principle in the presence of males. Males appear to reduce secondary attraction by producing a volatile substance(s) which may be anti-aggregating or repellent in its effect.

Topical application of a synthetic juvenile hormone, 1-(4′-ethylphenoxy)-3,7-dimethyl-6,7-epoxy oct-2-ene, to the eggs of the white pine weevil, Pissodes strobi Peck, inhibits embryonic development. Both embryonic and post-embryonic mortality were observed. The construction of simulated ovipositional twigs used in collecting weevil eggs of known age is described. Possible physiological methods of controlling the weevil are discussed.

Cyrtinus araguaensis n. sp. from northern Venezuela and Cyrtinus querci n. sp. from eastern Mexico are described and figured.

There is a correlation between the amount of blood ingested by Aedes aegypti (L.) and the trypsin activity (but not the chymotrypsin activity) in the midgut 16 and 24 hr after feeding. Puromycin and Dactinomycin ingested with a blood meal depress the level of midgut trypsin. Trypsin purified from the midguts of A. aegypti fed upon defibrinated blood containing 14C-amino acids contains radioactivity. Midguts from blood-fed mosquitoes did not produce significant amounts of trypsin when dissected from mosquitoes and maintained in a tissue culture medium for up to 50 hr.

Erannis vancouverensis Hulst occurs from northern British Columbia to central California, and has been occasionally reported at infestation levels. The larvae feed on young leaves of several species of deciduous trees; winter is passed in the egg or sometimes in the pupal stage; adults emerge during late autumn or occasionally during winter or early spring; females are wingless. The life stages, including larval instars, are described here in detail. Virus disease and parasitism by tachinid flies help control the species.

Sperm transfer in the desert locust, Schistocerca gregaria (Forsk.), is accomplished by means of small (1.5 mm) spermatophores, formation of the first of which begins almost immediately after coupling. A normal copulation, which lasts 4 hours or longer, results in the production of about 6 spermatophores and a maximum of at least 14. Some details of the process of spermatophore formation are presented and differences among certain groups of acridoids are discussed.

A study was conducted to determine the effectiveness of a novel insect growth regulator (IGR) with juvenile hormone activity. Tests show the third instar to be the stage most sensitive to the regulator based on reduction of fecundity throughout inhibition of normal adult development. Effective control in most stages was for the first time brought about within the realm of economic feasibility. The IGR could be of value in future control of aphid populations.

Six species of small crickets of the subfamily Nemobiinae are found in Canada. These are Allonemobius fasciatus (DeGeer), A. allardi (Alexander & Thomas), A. g. griseus (E. M. Walker), A. maculatus (Blatchley), Neonemobius palustris (Blatchley), and Eunemobius c. carolinus (Scudder). Synonymy is given and all distinctive taxonomic characters such as hind tibiae, concealed male genitalia, female ovipositors, male stridulatory veins, and audiospectrograms of stridulation are described and illustrated. A key to species is given and distribution maps are included.

Sex ratios at emergence of Aedes impiger and A. nigripes in the Hazen Camp area (81°49′ N., 71°18′ W.), northern Ellesmere Island, N.W.T., are given from trap records, mainly for 1963.

There is a marked predominance of females in trap catches from temporary ponds, and an overall slight predominance of females (but with marked pond-to-pond variation) in permanent ponds. The nature of these inter-pond differences favours the inference that, before emergence, males normally survive less well than females, especially under the conditions existing in temporary ponds as they dry up.

The spruce cone moth, identified as Dioryctria reniculella (Grote) by Heinrich and other authors, is described as D. reniculelloides n. sp. This and D. pseudotsugella Munroe form a compact group closely related to the European D. schuetzeella Fuchs. These three species are characterized. D. reniculella is sunk as a junior synonym of D. abietivorella (Grote), new synonymy.

Neocymbopteryx n. gen. type-species N. heitzmani n. sp., is described from Eureka Springs, Arkansas. The genus is a derivative of Cymbopteryx apparently adapted to diurnal activity.