The new cuticle is secreted around the old tentorium which breaks into four pieces. These pieces are withdrawn through the tentorial pits at the moult.

Laboratory tests of heptachlor-resistance in larvae and adults from treated and untreated farm populations of Hylemya floralis (Fall.) showed that only larvae were developing resistance. Therefore it is suggested that all life-stages of insect pests should be tested to determine which stage soonest reflects the highest level of resistance. This stage could be used to detect levels of resistance in the field and to permit alteration of control programs, to prevent development of complete resistance and the consequent loss of crop.

Third-instar larvae from the farm where all cruciferous crops had been treated with heptachlor annually, from 1952 to 1961, were resistant to 80 times greater concentrations of heptachlor than those from the untreated farm. From 1962 to 1964 the level of resistance remained constant in third-instar larvae from the untreated farm but it decreased fivefold in those from the treated farm. This decreased resistance is attributed to dilution of the population by non-resistant H. floralis from adjoining crops untreated during this period.

Adults of Melanoplus bilituratus (Walker) were reared in the laboratory as groups of pairs, as groups in association with mature and immature males, as single pairs, and as groups of unmated females. Females of grouped pairs produced a larger number of eggs per pod and laid a greater total number of eggs that were more viable and hatched at least one day earlier than those of other groupings. Hatchlings of grouped pairs were more robust, 29% reaching the adult stage, whereas only 12% of nymphs from eggs of single pairs reached adulthood. Eleven per cent of the eggs of unmated females were viable, although only one hatchling lived to become an adult. Females of grouped pairs, of single pairs, and of those that were unmated reached their peak egg production in four, five and seven weeks respectively, after becoming adult. Young females matured three days earlier when mated with old males than when mated with males of their own age.

Clover phyllody virus was transmitted from ladino clover to ladino clover by Paraphlepsius irroratus (Say). The preinfective period of the insect following acquisition of the virus was between 21 and 28 days. Nineteen of 25 plants fed on by leafhoppers that had completed their preinfective period became infected.

Theoretical objections to the hypothesis that polymorphisms are evolved as an adaptation by populations are discussed and upheld. Genetic data do not support the assumption that potency balance systems controlling polymorphisms are widespread in the Lepidoptera and are responsible for the prevalence of polymorphisms sex-limited to the female. It is pointed out that such polymorphisms are commoner in butterflies than in moths and that this requires an ecological, not a purely genetical, explanation. It is suggested that the presence of two potency balance systems in the genus Choristoneura could have resulted from an interchange of genetic material between the X-chromosome and an autosome during the evolution of the group.

Three new species of Anomiopsyllus Baker, A. martini, A. durangoensis, and A. sinuatus, are described from the State of Durango, and a new subspecies, A. hiemalis mexicanus, from the State of Chihuahua, Mexico. Host-relationships and distribution of the Nearctic genera of Anomiopsyllinae are summarized, and a key to males of the twelve known species and subspecies of Anomiopsyllus is provided.

In population studies of the pine leaf adelgid, sampling techniques are required. Procedures for sampling galls on spruce and for associated adelgid stages are described. Gall distributions both within trees and between trees are non-random, following the negative-binomial series. Aggregation within trees arises from a disproportionate number of galls occurring on the upper crown branches. Between trees, gall populations are more dense on the larger trees, and red spruce is more heavily infested where red spruce and black spruce are mixed. The proposed sampling unit is composed of one branch from each of the upper two vertical crown quarters, and one longitudinally halved branch from each of the lower crown quarters. The examination of sample units from 50 trees will provide a reliable estimate of stand populations except where low gall densities or heterogeneous spruce stands make a larger sample mandatory. Additional details of sampling and the biological significance of the findings are discussed.

Parablastothrix Mercet, which has been known only from the Palearctic, is represented in the Nearctic by Parablastothrix neorctica new species, which is described and figured. The type and allotype of P. nearcticus were reared from a species of Coptodisca Walshm. (Lepidoptera) mining leaves of Vaccinium arboreum Marsh. at Jackson, Mississippi. One paratype was reared from Obrussa sp. (Lepidoptera) at Morgantown, West Virginia, and the other collected in Livingston Co., Michigan.

Descriptions and figures are presented of both adult and immature stages of a new species, Fannia moseri, from nests of Atta texana in Louisiana; and the female and larvae of F. binotata Chillcott, and mature larvae of F. americana Malloch, from nests of Bombus spp.

Group VI of North American Ips contains I. perturbatus (Eichhoff), I. hunteri Swaine, I. utahensis Wood and I. woodi Thatcher. A key and descriptions of species are given. Members of this group have the third declivital spine capitate with the tip conical and acute. The front of the head is evenly convex except in females of I. utahensis which have the lower part of the frons faintly elevated. I. woodi breeds in pine while the other three species breed in spruce.

Problems associated with quantitative estimations of mixed populations of several species of predators on apple trees are discussed. The problems arise largely because of the inherently high variability in such populations and because of the mechanical difficulties of counting predators on some basic unit of tree. In this investigation two devices used in sampling are described and their efficiency rated. One, a vacuum sampler, that removed predators from samples of leaf clusters on the tree failed to meet the standards set. The other, called the shaker sampler, tumbled clusters about in a revolving wire screen cage to dislodge predators for counting. The amount of processing with this device to remove practically all predacious specimens was calibrated. When the shaker-sampler technique was applied to studies in two orchards it proved to be practical for quantitative estimation of predator populations per large limb. The error associated with estimations of the density of individual species was usually very high so that pooling of the results for several or all species was required to reduce the variance to an acceptable level.

A new species of Perniphora Ruschka reared in Maine, U.S.A., and New Brunswick, Canada, from logs of white and yellow birch infested with ambrosia beetles, especially Trypodendron betulae Swaine, is described and illustrated. It is compared with the only other described species, Perniphora robusta Ruschka, a Palearctic species which has been reared, according to Ruschka (1923), Novak (1960a, b), Balazy (1963) and Hedqvist (1963), from a number of ambrosia beetles, especially Trypodendron lineatum Oliv., in Germany, White Russia, Czechoslovakia, Poland, Denmark, Finland and Sweden.

Group VIII of North American Ips contains I. interruptus (Mannerheim), I. engelmanni Swaine, I. amiskwiensis G. Hopping, I. sulcifrons Wood, I. pilifrons Swaine, I. yohoensis Swaine, I. tridens (Mannerheim) and I. semirostris G. Hopping. Females of some species have dense brushes of long setae or pads of short pile covering the frontal protuberance. Species are described and a key is given. All of them breed in spruce, six in the boreal forest and two farther south in the Rocky Mountains.

The acceptability of host plant extracts on pith, charred filter paper, and an agar diet, and vacuum infiltrated into lettuce leaves was compared on three species of Lepidoptera and two of Coleoptera. The vacuum infiltrated lettuce was eaten by two of the Lepidoptera and it was the only method acceptable to the Coleoptera. The agar diet was eaten by the three Lepidoptera while pith and charred filter paper were acceptable to only two of them. It is concluded that vacuum infiltration of lettuce leaves is a useful method for the bioassay of host plant extracts to determine if they contain insect feeding token substances.

The life history of Chrysomela crotchi, a univoltine species commonly found on trembling aspen, was studied in northwestern Ontario from 1959 to 1962. The most striking feature of its life history was the longevity of adults, which were capable of overwintering two successive years. Overwintered adults became active and began feeding in late May, and oviposition occurred from early June to late July. The incubation period was approximately 10 days and the three larval instars required approximately one month for development to the adult stage.

Females laid more eggs during their second season and the highest number laid was 326. The number of eggs in an egg mass averaged 37.6, and the average interval between the deposition of egg masses was 4 days. Males and females mated more than once, but only one mating was necessary for a female to produce viable eggs throughout the season. Males were capable of fertilizing more than one female and remained potent for more than one season.

Parasitism was low, and only two species of larval parasites were reared. Several predator species were observed preying on the immature stages. Predation and overwintering mortality appeared to be the most important control factors.

The relative toxicity of Kelthane (1,1-bis (p-chlorophenyl) -2,2,2-trichloroethanol), and parathion to Phytoseiulus persimilis Athias-Henriot and its prey, Tetranychus urticae K. (= telarius (L.)), was determined using a Potter Spray Tower. Parathion was found to be far more toxic to P. persimilis than was Kelthane. The LD50 values for Kelthane were 0.051% and 0.29% for T. urticae and P. persimilis respectively, and for parathion were 0.050% and 0.0044% respectively. The LD95 values bore a similar relationship to each other. The two materials were equally toxic to T. urticae. Therefore, use of Kelthane rather than parathion in an environment where P. persimilis and T. urticae were interacting would favour the beneficial species. The statistical aspects of the test method are discussed.

Nuclear-polyhedrosis virus, introduced into virus-free populations of the forest tent caterpillar, Malacosoma disstria (Hübner), in 1963, was carried over into the 1964 host generation and was spread into the surrounding areas from the points of introduction. The extent of spread in 1964 appeared to be influenced by the size of the area treated in 1963. In 1964 the epizootics developed slowly during the early instars and reached the highest levels late in the last instar. Many infected larvae crawled to the tops of the trees and died while eggs were being laid, thus, some egg masses were contaminated. This is one means by which virus may be spread from one generation to the next, but egg-transmission by adults appears to be the main method of spread over wide areas. Adults of the dipterous parasite, Sarcophaga aldrichi Park, may be important dispersal agents of disease in localized areas because they feed on virus-diseased larvae and are present from the time larvae enter the third instar until after adults have oviposited.

Observation of ecdysis in one male and three females of the spider Philodroms rufus Walckenaer (family Thomisidae) has revealed a hitherto unreported source of food for newly molted spiders. After hanging suspended from their exuvia by the spinnerets for a few minutes, the spiders suddenly flexed their legs and ran quickly from base to tip of each exuvial leg, pressing their mouthparts along the limbs. On reaching the tip of each tarsus the spiders bit the old cuticle, allowing a column of colorless liquid that extended through the distitarsus and basitarsus and part way up the tibia to be withdrawn steadily and rapidly. One of the spiders drew the liquid from only four of the exuvial legs, while the others drew from all eight. Having fed, the spiders were immediately capable of normal activity.

Ten alfalfa clones, Medicago sativa L., were tested at 60°, 70° and 80° F. in Kansas and Quebec for resistance to pea aphid biotypes, Acyrthosiphon pisum (Harris), originating in the respective areas.

The resistance of the clones at the three temperatures varied differentially at the two locations. One clone was resistant at all temperatures to aphids of both locations. Results indicated that biotype C61-86 of the pea aphid at St. Jean, Quebec, is biologically different from the population of the same species in Kansas. Results also suggest the possibility of finding or combining clones so that varieties of alfalfa resistant to pea aphids over broad geographic areas and environmental conditions can be secured.

The genus Balsameda Thomson is elevated from synonymy and redescribed on the basis of the type species, Cotinis pulverulenta Burmeister. One additional species, Cotinis adspersa Sharp, is referred to the genus. Both species are described and the male and female genitalia are illustrated.