Experiments were designed to find the functional response (response per predator) of the pentatomid Podisus maculiventris to the population density of larvae of the fall webworm, Hyphantria cunea. The response was measured in confined universes, (glass jars), representing webworm nests, and it was found permissible to vary universe size, within certain limits, in order to obtain a wide range of prey densities without handling large numbers of larvae. The “disc equation” proposed by Holling (1959) was found to describe the response curves, except at very high prey densities, and to provide a satisfactory biological explanation for their decreasing slopes. P. maculiventris ingests about 84% of its own weight for each fifth-instar larva of H. cunea attacked successfully, and the time spent in feeding and becoming hungry enough to make another attack reduces very substantially the time devoted to searching activities. Both prey defense (Fig. 1) and the age of the adult predator (Fig. 2) have very important effects on the functional response curves and on the values of the parameters, a and b, of the disc equation. These effects are explained. The “rate of discovery”, a, is contrasted to Nicholson's (1933) “area of discovery” and it is shown why the former is more likely to be independent of prey density than the latter.

In view of the population of webworm larvae in the average nest, it is concluded that the functional response of the various predators inside the nest is probably not important, and that attention should be devoted instead to the functional and numerical responses of predators and parasites to the density of nests per unit area. Because of the vigorous defense exhibited by fifth-instar webworm larvae, predation by timid predators like P. maculiventris is selective and larvae whose development is delayed by parasitism are likely to suffer more predation than healthy larvae.

It is well known that the membranous areas of lepidopterous larvae may lose much of their colour pigment when the larvae are preserved, but it appears to be less widely recognized that the larvae themselves mav also be burned by the preservative. A pale larva, one that is greenish or yellowish when alive and almost cream-coloured when preserved, becomes brownish under these circumstances. The colour change may be so pronounced as to result in mis-identification of the species, and a colour description based on a series of such larvae may be most inaccurate.

The phytophagous mite Oligonvchus bicolor (Banks) has been observed feeding on red oak, Quercus borealis Michx. f., at Kentville, N.S. It has not previously been reported in Canada east of Ontario. McGregor (1950) reported this mite as being found on chestnut, hickory, maple, oak and spruce in Connecticut, New Jersey, New York, North Carolina and Washington. Pritchard and Baker (1955) studied specimens taken from oak at Ithaca, N.Y., red oak at Hamden, Conn. and Washington, D.C., willow oak and white oak at Durham, N.C., and pin oak at Lawrence, Kansas. Garman (1923, 1940) found it common on oak and also present on chestnut, maple, hickory and birch. Johnson (1956) reported O. bicolor fairly common in Connecticut and believed its distribution to be the east coast of the United States. He stated that it was the most important mite species on chestnut in Connecticut and that when present occurred in large numbers. Caesar and Ross (1921) found O. bicolor heavily infesting ornamental oak trees in different parts of the Niagara district of Ontario.

Macrocentrus ancylivorus Rohwer overwintered in larvàe of the strawberry leaf roller, Ancylis comptana fragariae (Walsh & Riley), at the rate of from 544 to 7,623 per acre of strawberry field. Not more than 300 per acre of peach orchard, could be expected to overwinter in larvae of the Oriental fruit moth, Grapholitha molesta (Busck). About half of the larvae of M. ancylivorus in leaf rollers did not survive the winter.

The fore wing bases of Monotrysia can be homologized with the plan for a generalized insect wing base (Snodgrass, 1935). The wing bases of advanced Lepidoptera are very different from those of primitive forms. An evolutionary series can be traced through the order showing how the changes may have taken place.

The positions of the bending cuticle areas vary very little within the order. Within each superfamily the axillary region is surprisingly constant. It is impossible to distinguish between the wing bases of many related ditrysian families.

The jugum is particularly interesting; it is present in all the members of the old group “Microlepidoptera” and not only in the Monotrysia or “Jugatae”.

Laboratory studies show that diapause, or eonymphal development, has a temperature optimum approximating 8 °C, at which some 29 days are required for its completion. The optimum for morphogenesis is 22 °C. About 33 and 37 days for females and males, respectively, are required for its completion.

Field data for three sites with mean temperatures near 22, 19, and 16 °C. show that emergence took place earliest at the intermediate site and latest at the exposed site, which experienced the highest mean temperature. Emergence of males and females overlapped, but at the shaded site, having the lowest mean temperature, females emerged sooner than males, whereas the reverse was observed at the exposed site.

The length of the eonymphal stage in the field is dependent upon site temperature and can be predicted from laboratory data. The duration of the pronymphal stage is dependent not only upon site temperature, but also upon the length of time which has been required for eonymphal development. Thus the longer the eonymphal period. the shorter the pronymphal period. This compensatory mechanism is probably due to a temperature effect on any morphogenesis that takes place concurrently with diapause.

A highly sensitive bioassay of the olfactory response of I. confusus is described. The response of beetles to air streams carrying attractants is a chemoklinotaxis but positive orientation occurs only in moving air. There is no evidence of ameno-taxis in odorless air streams or orientation to attractants in still air. Male behavior is characterized by an “area” orientation near the attractive material, an indirect approach to the source as shown by their entering adjacent air channels, and stopping frequently in the traverse during which they make klinotactic movements. The females exhibit a “point” or “straight-line” response, crawling directly to the source, rarely deviating into adjacent channels and only occasionally interrupting their approach.

Bark-wood samples of ponderosa pine become attractive 4-6 hours after male beetles are introduced into preformed entrance tunnels, the peak attraction occurring between 18 and 144 hours. Frass is not attractive until 9-12 hours after introduction of males. The ratio of females to males responding positively during the peak attraction period was approximately 8:5. The level of attractiveness to females falls as the season progresses, the highest response being recorded in late May and June. Sexual maturity as judged by the appearance of motile sperm was not correlated with host feeding or the initiation of attraction. Frass of males boring in Douglas fir was unattractive to females.

Attraction is initiated by male feeding in the phloem-cambial tissue of a host and is delayed until the first food has passed through the gut. The attractant appears to be associated with male excrement and may be produced, at least in part, in the hindgut.

Four indigenous parasites of R. buoliana are discussed: Exeristes comstockii (Cress.), Scambus hispae (Harr.), Scambus tecumseh Vier. and Itoplectis conquisitor (Say). The first three are external larval parasites and the fourth an internal pupal parasite. Observations are given on the hosts, life histories, and habits under laboratory conditions. The immature stages are described.

Ips concinnus (Mannerheim) and Ips mexicanus (Hopkins) comprise Group I of the genus Ips DeGeer (Coleoptera: Scolytidae). Members of this group have 3 spines on each lateral margin of the declivity and strongly arcuate sutures on the anterior face of the antennal club. I. radiatae Hopkins is placed as a synonym of I. mexicanus (Hopkins). I. concinnus breeds in Picea sitchensis in the coastal region from Alaska to southern Oregon. I. mexicanus breeds in various species of pines from Alaska to Guatemala and eastward in the United States and Canada to the Rocky Mountains. A key to the species and descriptions are provided.

A survey of the sucking insect fauna of the birches has been conducted in the Maritime Provinces, and a check-list of 75 species of Homoptera and Hemiptera, with tabulated data on host relationships, is presented. The bulk of the population on any of the three birches (Betula alleghaniensis Britt., B. papyrifera Marsh., and B. populifolia Marsh.) has three major components: the Oncopsis leafhoppers, Psylla striata Patch, and the phyllaphidine aphids. The many other species present occur at much lower density but often have a broader dependence upon other hosts. The main homopterous families and their relationships to birch and the forest communities are discussed.

Several criteria for determining the sex of the southern pine beetle, Dendroctonus frontalis Zimm., were investigated. The combination of the prominence of the frontal tubercles and depth of frontal groove was 100% accurate and was chosen as the best criterion. Data on sex ratios at different points in the beetle's life history are given.

From May 8 to September 29, 1961 4 species of Corixidae, 5 o f Notonectidae, 1 of Belostomatidae and 1 of Nepidae were collected and the seasonal distribution of each species was noted.

Estimates of the numbers of the western pine beetle, Dendroctonus brevicomis LeConte, in Pinus ponderosa Laws, bark samples were made by radiographs of 25 bark samples and by dissection counts of the bark. High correlations (r = >.9) between the two methods were found for (a) live larvae, (b) live plus dead larvae, (c) live of all stages combined, and (d) live plus dead of all stages combined. The bark dissection method took eight times as long and was 4⅓ times as expensive as the radiographic interpretation method of estimating bark beetle numbers.

External morphological differences between male and female adults of Sitophilus granarius (L.), useful for quick and accurate sexing, have been described and compared with differences described by other authors.