Fifth-instar larvae of the larch sawfly, Pristiphora erichsonii (Hartig), of different weights, were deprived of food and placed in containers with moist moss. A low percentage of the early fifth-instar larvae were able to spin cocoons, but the percentage rapidly increased to a plateau as the larval weight increased. All but the heaviest larvae suffered appreciable mortality before first-year adult emergence was complete. A curvilinear relationship between larval weight and survival to the adult stage or to larvae in prolonged diapause is evident. The percentage of mature ova in adult females was reduced at the lower larval weights, with corresponding increases in the percentages of near-mature and large immature ova. There were linear relationships between larval weights, adult weights, and numbers of oöcytes. A method for assessing premature larval drop and other causes of mortality under field conditions is described and data for a number of years and plots are presented. Variations in the percentages of unparasitized normal late fifth-instar larvae were large. Data indicate that parasitism by Olesicampe (Holocremnus) sp. nr. nematorum (Tschek) and Bessa harveyi (Townsend) is the most important factor, probably a key factor, contributing to this variation.

Transport and dispersal of odours by air currents is considered an important factor in scolytid response to attractant sources. This viewpoint provides explanations for some puzzling field observations and data, and helps identify significant questions about scolytid flight behaviour. There is a need for "odour meteorology", which would be concerned with the rates and types of odour distribution near the ground, and would provide a basis for the most effective use of chemical attractants in natural environments.

The morphology of haemocytes of Blaberus giganteus (L.) was studied in vivo in adult insects, and in stained films of blood from all stages. The study included the measurement of cells and the application of several histochemical tests. It was concluded that four categories of haemocytes exist, prohaemocytes, plasmatocytes, granular haemocytes, and spherule cells, and that the last two categories are closely related, both having the capacity to concentrate neutral mucopolysaccharides in their cytoplasm. Criteria for separating the categories are given.

After feeding, gypsy moth larvae construct a silk mat (resting mat) on which they remain. Prior to molting, this mat is reinforced, or a new, dense mat is constructed (molting mat). Late in the last larval instar, a sparse cocoon is constructed. When larvae are starved, a shift in behavior is noted, with increased locomotion, irritability, and the trailing of a strand of silk as larvae wander. First-instar larvae, quiescent and anchored on resting mats, are not readily induced to spin down on silk threads; hence are not readily dispersed by wind. Hungry first-instar larvae, more apt to be spinning down, are presumed to be more readily dispersed by wind. Larvae which undergo an additional instar have a longer prefeeding phase and might be more readily dispersed than "normal' larvae. The effects of hunger may also cause the shift in diel periodicity of mid- and late-instar larvae, resulting in some dispersal of these larvae away from areas where food will be depleted.

Laboratory tests of heat tolerance of last-instar larvae of the larch sawfly, Pristiphora erichsonii (Htg.), were made to provide information for the evaluation of the role of high temperature as a mortality factor in field populations.

Test larvae were reared from eggs at 21 ± 1.5 °C and 50 ± 10% relative humidity. LT50's were determined at 37°, 39°, 40°, and 41 °C for larvae conditioned at 30 °C and 75% relative humidity.

Larvae were less heat resistant during the first 24 hours after molting than they were 24 to 48 hours after molting. The conditioning temperature and the duration of conditioning had very significant effects on heat tolerance. Differences in acclimation due to heat treatment could not be accounted for by differences in free water content.

Temperature acclimation will occur in field populations and must be considered in evaluating the role of high temperature as a natural mortality factor.

Larvae may encounter lethal temperatures when wandering on branches or tree trunks or crawling on dry ground in open sunshine.

Parapilocrocis n. gen., with type-species A. citribasalis n. sip., is described from Bolivia and Peru, with type locality Alto Palmer, Bolivia, 1100 m.

A trap that excludes grain kernels but permits the entry of grain beetles and mites is described. It may be used as a sampling device to detect insect infestations in stored grain. Sampling may be done with little disturbance to the surrounding grain and since the insects cannot escape, the trap can be left in position for prolonged periods.

Various aspects of the behavior of I. confusus (LeConte) relating to the production of and response to male attractant were studied. Storage at 8.0 °C and 100% R.H. had no adverse effect on survival, response to male attractant, or predisposition to fly. Low humidity and high temperatures (21 °C) adversely affected behavior and survival. Beetles conditioned either in natural or constant environments responded at high levels throughout a 24-hour period. Female response to male frass reached a low of 24.2% in January and February and rose to a peak of 76.6% in May and June. Response to benzene extract of male frass fell moderately during autumn and winter, indicating a lowered response ability for overwintering populations. Male response was lower and more erratic but followed the same seasonal trends.

After brief exposure periods, even previous nonresponders oriented to male attractant at significantly higher levels than the total original population. Long-term confinement in an atmosphere containing male frass odor caused a reduction in response of both sexes to male frass extract, presumably because of adaptation of olfactory receptors.

Flight attempts by both sexes occurred between 25° and 40 °C but were severely inhibited at these extremes. Light intensities below 431 luxes suppressed flight. Optimal take-off temperatures were 30 °C for males and 32.5 °C for females. Both contact with male frass and with attractive air reduced the take-off attempts of both sexes to near zero. Attractive odor in the air still suppressed flight significantly after beetles had been conditioned up to 4 hours in contact with male frass.

Teneral males produced attractant after a long maturation period. Single, mature males produced attractant up to 18 days, but after mating, productivity declined in direct correlation with the number of females per male. Single males produced frass throughout the day but maximum production was coincident with peak female emergence and flight. Male frass was significantly less attractive 15 minutes after exposure to open air and after 1 hour, very little attraction remained.

No trends in the ability of newly emerged adults to respond to male attractant were noted over a 30-day period. Emerging brood and re-emerging parent adults are responsive to flight stimuli, but darkened callows and parent adults removed from galleries could not be induced to fly. Reproducing females show a greatly reduced response to male attractant.

The distribution of Douglas-fir tussock moth (Hemerocampa pseudotsugata McD.) egg-masses on white fir (Abies concolor (Gord. and Glend.) Lindl.) was studied in three areas of northern California. In each area 100 trees between 4.5 and 8.4 in. in diameter were stratified into five defoliation classes and four crown classes, giving a total of 20 classes per study area with five trees per class. Trees were divided into four crown levels and samples were taken at each of the cardinal directions at each level. Two branches comprised n sample unit in the top half of the tree (eight branches per level) and one branch the sample unit in the bottom half of the tree (four branches per level). Egg masses were recorded per 10 sq. ft of foliage or branch area. Eighty per cent or more of the egg masses were found in the bottom half of the crown. This percentage in the bottom half of the crown increased on trees with heavy defoliation or with increased exposure of the crown. Of the four possible sources of variation considered in this study, crown level, defoliation class, and crown class were significant while cardinal direction was not. A sampling method is proposed on the basis of the information gathered in this investigation.

Corthylus columbianus Hopkins became permanently established in. the study area in southern Indiana during 1940–62. Three epicenters were present in 1945. Two of these shifted, expanded, and merged the following year. The two remaining epicenters merged during the first outbreak. As the population declined after the first outbreak and began retreating toward the center of the stand, two epicenters were again definable. One of these alternately expanded and contracted for several years demonstrating, qualitatively, that epicenters are definable and dynamic in time and space. That is, any particular locus undergoes some degree of areal shift each year and varies in size through time.

Quantitatively, attack and egg cradle densities within the epicenters follow the same pattern. Densities were generally lowest in the newly invaded areas. Except during epiphytotics, highest density areas were usually aggregated near the center of the stand, but shifted from year to year. For example, only one tree contained a high density in 1954; by 1956 the high density area had shifted spatially and encompassed 10% of the study trees.

An “indigenous population” of C. columbianus is an areal concept. The insect withdrew to certain areas, not certain trees, during times of low population numbers. The “brood” tree concept–a single tree containing all or a majority of the population during times of low population numbers–is rejected in the case of the Columbian timber beetle for the study area in southern Indiana.

This paper is the first in a series on the Lepidoptera of the Sierra Madre Occidental area of Durango, Mexico. The immature stages of eight species of Geometridae are described in detail: Grossbeckia semimaculata Barnes and McDunnough, Semiothisa cyda (Druce), Galenara lallata (Hulst), Glena interpunctata interpunctata (Barnes and McDunnough), Iridopsis sp., Anacamptodes angulata Rindge, Phaeoura kirkwoodi Rindge, and Sicya snoviaria Hulst. Less detailed descriptions or short notes are given for the pierids Colias caesonia (Stoll) and Eucheira socialis Westwood; the arctiids Halisidota propinqua Henry Edwards and Arachnis perotensis Schaus; the noctuids Lichnoptera gulo Herrich-Schaeffer and Lacinipolia eucyria Dyar; a notodontid, Disphragis edwardsi Druce; a lasiocampid, Malacosoma incurvum aztecum (Neumogen); a pyralid, Dioryctria rossi Munroe; and an olethreutid, Petrova albicapitana (Busck).

The first record of the occurrence in North America of the white-tipped clover case-moth, Coleophora frischella L., was made in June 1966 when a single adult was taken by Heinemann on Picton Island, N.Y., in the St. Lawrence River (Freeman, personal communication). Independently, Trieselmann collected the larvae from white sweet-clover, Melilotus alba Desr., on 28 July through to 8 August 1966 at many points around Pembroke, Ont. Detailed examinations made at two of the collection points indicated that between 15 and 20% of sweetclover seeds were damaged. Because of its potential economic significance, the authors wish to make the presence of this species known to agricultural entomologists in Canada and the United States.