Females of Spalangia cameroni Perk, use the ovipositor to differentiate between unparasitized and parasitized housefly (Musca domestica L.) pupae; and prefer to lay on unparasitized hosts instead of those attacked by S. cameroni, Nasonia vitripennis (Walk.), or Muscidifurax zaraptor K. & L. (Hymenoptera: Pteromalidae). The intensities of oviposition restraint on the three kinds of attacked hosts are similar. Changes in parasitized pupae to which the female parasites react probably involve "venoms" injected by each species during oviposition.

Life tables were prepared from daily fecundity and survival data on 69 apterous black bean aphids, Aphis fabae Scopoli, and 47 apterous pea aphids, Acyrthosiphon pisum (Harris). Both were on broad beans in 20° ± 0.5 °C, 70–80% R.H., and 16 hr light per day. The intrinsic rates of natural increase (rm) computed from the life tables were 0.359 ♀/♀ day for the bean aphid and 0.404 ♀/♀ day for the pea aphid. Mortality was not important in determining the rates of increase because very few aphids died during their reproductive periods. Only 5 of 116 reproducing aphids died, all from inability to extrude nymphs which had died before bursting their embryonic membranes. These nymphs became covered with a discharge from the mother which cemented them in place and prevented the birth of succeeding nymphs. The resulting engorged females died in 3–4 days.

An analysis of and comparison with life tables of two other aphid species in addition to those produced here showed that the differences in rm were due almost entirely to differences in fecundity. Two fecundity patterns, correlated with aphid phylogeny, were recognized.

Field studies enabled the identification of some limiting factors to which parasitoids were exposed in exploiting the sawfly host, Neodiprion swainei Middleton, and aspects of their quantitative and qualitative impact on the host population. Emergence patterns and flight activity of parasitoids in the spring indicated that larval parasitoids were vulnerable to hyperparasitism by cocoon parasitoids. Although cocoon parasitoids were limited by a shortage of time in which to exploit the host in the spring they still reduced the overwintered host population by 66% in 1969. All forms of predation caused less than 10% sawfly mortality so parasitoids formed the major mortality factor in the spring. Sawfly in prolonged diapause appeared to be immune from cocoon parasitoid attack and thereby efficiency of these parasitoids was limited. However, cocoon parasitoid activity was selective on sawfly that would normally have emerged early in the season and thus delayed the average development of the host population. The complex food web based on the sawfly host provided a sensitive buffering mechanism to produce a degree of stability in the host–parasitoid interaction. The composition of the parasitoid faunae before and after establishment in N. swainei populations of the introduced Pleolophus basizonus (Gravenhorst) indicates the rapidity with which the parasitoid became influential in the complex.

Loewia foeda (Mg.), a European parasite of the centipede Lithobius, is recorded from two localities in New York State where it has evidently become established as an addition to the Nearctic fauna. The adult is redescribed and figured and its life history briefly reviewed.

The apple aphid was reared on 1-year-old trees in a controlled environment cabinet with simulated mid-June through October 1968 daylengths and temperatures. Maximum rates of increase (ca. 2.7-fold per week) were observed during the first 5 weeks of the experiment and maximum populations were obtained in 7 weeks at the time the trees stopped growth when the diel photoperiod was 14.8 hr, and light/dark temperature was 20.5°/15.5 °C. The ratio of nymphs to adults increased from 5:1 to 10:1 from week 2 to week 8, followed by a rapid decline. At week 12 there were more adults than nymphs and the nymph:adult ratio remained 1:3 through the remainder of the experiment. Alate aphids appeared 2 weeks following infestation, increased very rapidly, ca. 6-fold per week, and maximum abundance was noted at the end of 6 weeks. Their numbers declined nearly as rapidly at ca. 0.35-fold per week and they were not seen after week 11. As the numbers of alate aphids decreased, apterous adults increased to week 12, remained constant to week 15, and slowly decreased in an environment of shorter daylengths and lower temperatures. The rate of apterous adult aphid increase was similar to the rate of accumulated degree days during the first 8 weeks and again in the 10- to 15-week period.Aphids were concentrated on the tree tops during the first 6 weeks of the experiment. A gradual migration followed and the aphids became dispersed over the trees with minor concentrations near the centers of the trees.

Differences in weevil attack between trees containing crystallizing and non-crystallizing resin were observed. Among twenty non-crystallizers only three trees were successfully attacked by the white-pine weevil. About 50% of the remaining population was successfully attacked. Resin crystallization can thus be used as a characteristic to screen for resistance to the white-pine weevil.Since several other characteristics such as leader diameter, depth of cortical resin ducts and bark thickness are also related to weevil resistance, a discriminant function could be developed to maximize discrimination between susceptible and resistant trees by a properly weighted combination of characteristics related to weevil resistance.

Reciprocal field tests of attraction between populations of Ips pini (Say) from California, Idaho, and New York disclosed geographic variation in pheromone systems. These differences reside both in pheromone production and reception. However, it is unknown whether variation in the pheromone bouquets is qualitative, quantitative, or both.

In New York, both sexes responded in higher numbers to their own pheromone than that produced by California or Idaho males. In California, beetles of both sexes discriminated against New York, but in Idaho only females made this distinction. In both California and Idaho, the local population showed a slight preference for the pheromone produced by Idaho males over that produced by California males.

The predator Enoclerus lecontei (Wolc.) demonstrated a four-fold preference for attractants produced by males from New York over those produced by beetles from California and Idaho. The parasitoid Tomicobia tibialis Ashmead showed the opposite trend.

There is no evidence that geographic variation in the pheromones produced by I. pini is sufficient to enforce breeding isolation between adjacent populations. However, these results dramatize the necessity of considering pheromonal variability in programs applying pheromones for the survey and control of widely distributed pests.

These studies show that Orgilus obscurator-purasitized Rhyacionia buoliana larvae initially gain weight in a manner similar to unparasitized larvae, but eventually attain a much smaller maximum size and then slowly decrease in weight with time. This decrease in weight is caused by the feeding of O. obscurator. The rate of increase in weight by O. obscurator increases with time during the second to fourth instars and decreases slightly during the fifth instar. During the fourth and fifth stages, the weight of O. obscurator changes from an initially minute proportion of the combined host–parasite weight to a significantly large proportion, eventually attaining ca. 80% of the combined weight. The feeding and activity of parasitized hosts remain high and continue for ca. 1 week longer than that of unparasitized hosts, resulting in a higher potential for damage to the host tree. Moulting of host larvae seems not to be affected by the presence of O. obscurator, although parasitized larvae remain in a "juvenile" state and do not develop testes. The implications of the size relationships of O. obscurator with its host on the activity of another parasite, Hyssopus thymus are discussed, and it is noted that parasitized hosts, on the average, needed fewer moults to complete their post-winter development than unparasitized hosts. This phenomenon is related to synchrony of the adult parasite with its host, and to host behaviour.

Hoplochaitophorus spiniferus is described from swamp white oak, Quercus bicolor Willd. A key to the three known species of the genus is given.

Aulacorthum clavicornis, A. pterinigrum, and A. scabrosum are described and illustrated and a key to Canadian species is given.

Average fecundity of free-living and caged female Psylla pyricola Foerster on pear trees was reduced by high summer temperatures and low host vigor. Implications of these observations in the planning of control programs is discussed.

This report deals with studies of the biology of 10 species of the genus Triatoma Laporte, all of which were collected in Argentina and reared in the Microbiology and Parasitology Institute of the School of Medicine, University of Buenos Aires.The specific purpose of the study was to determine, for each species, average values for number of eggs per female, proportion of eggs hatching, time required for hatching and for the development of each instar nymph, the longevity of female and male adults, and the length of egg-adult and egg–egg cycles.These studies extend the knowledge of the biology of vector species of Chagas’ disease and have been done in conjunction with studies of the geographical distribution of the insects.

Five species of Noctuidae are known to occur in the Canadian far north: Anarta richardsoni Curt., Lasiestra leucocycla Staud., Sympistis labradoris Staud., Syngrapha parilis Hbn., and an Apamea species that is probably exulis Duponchel. The larvae of these species are described and illustrated. A key to them has been prepared, although they can be distinguished without difficulty except for some specimens of Anarta richardsoni and Lasiestra leucocycla.

Seventeen new species of Scolytidae from Mexico are described. The new species represent the genera Sampsonius (1) of the Xyleborini and Corthylus (9), Corthylocurus (1), Tricolus (2), Monarthrum (3), and Amphicranus (1) of the Corthylini.

New locality records are given for eight previously described species.

The relative importance of position and color in nest-entrance recognition was tested in two bumble bee species, Bombus griseocollis (Degeer) and B. occidentalis Greene, using two identical sheds, each bearing a horizontal row of four nest-entrances marked with colored discs to which workers returned after foraging in the field. The bees were trained successively to either a yellow or a green disc on each of the four positions (alternating between the sheds), the other three positions being marked with black discs during each training period. The positions to which bees returned after moving the colored disc to each of the other three positions following each training period were recorded.The results indicate: (1) that the importance of position relative to color was greater at the end positions than in the inner positions; (2) that whereas B. griseocollis relied more on color relative to position than did B. occidentalis when the bees had been trained to the outer positions, the converse held true for inner positions; (3) that position was more important relative to color when the bees were homing than when they were choosing a position at which to alight or enter. Ecological and behavioral implications of the results are discussed.

Behavior of the pine engraver Ips pini (Say) was observed through plexiglass rearing chambers containing ponderosa pine (Pinus ponderosa Lawson) phloem. Periods of jostling in each entrance tunnel between the resident male and entering female preceded a female’s admission to the nuptial chamber. On the average, mating was completed in 25 seconds. In the gallery, beetles walked on protibial spines, keeping their tarsi folded against their tibiae. Eggs were deposited in niches on either side of the egg gallery and covered by phloem fragments. Larvae mined at right angles to the egg gallery and formed their molting chambers by doubling back and packing frass tightly against that already in the gallery. Larvae consumed their exuviae shortly after molting. Feeding by callow adults on prepupae and pupae may be an important natural control.

Three new species of aphids are described from collections made on Mt. Sutep in northwest Thailand: Cinara khasyae new species; Greenidea (Trichosiphum) chiengmaiensis new species; and Macrosiphum (Sitobion) yongyooti new species. The status of Greenidea (Trichosiphum) siamensis Takahashi is changed from variety to species.

Fecundity and colony size of Hyphantria cunea Drury were measured in six census areas for 13 years, and wing length was measured in one area. Colony size in the fifth instar was closely correlated with fecundity, and the percentage mortality from the egg stage to the fifth instar was an inverse function of fecundity. Wing length was not a sensitive index of fecundity where there was insufficient competition for food to cause severe reduction in moth size.Seasonal differences in fecundity and colony size within years, as well as differences between areas and between years, followed patterns expected from laboratory studies. Decreases during each season, proximately attributable to the age of foliage available to the larvae and ultimately attributable to genetic differences in the heat requirements for diapause termination, made it difficult to estimate mean fecundity for any area or year. Fecundity seemed slightly higher in coastal than in inland areas. Both population quality and weather appeared to influence annual differences, but because of the complex interaction between them and the high variability in fecundity and colony size, the relationships could not be modeled effectively with the available data.Differences in fecundity and colony size associated with both time and place were negligible in comparison to the changes in the population density of colonies, as measured in the same areas over the same period of years. It is concluded that priority should be given to survival rather than fecundity in the development of population models for H. cunea, at least in areas where competition for food is not severe.

Five biotypes of the pea aphid, Acyrthosiphon pisum (Harris), from four hosts were recognized by their differential survival and rates of population increase on broom, white clover, alfalfa and broad beans, by body size, colour, and rates of natural increase (rm) on broad beans. A simple method is described which can verify that the differences between rm values measured by life table analysis are not due to chance.

Four of the biotypes were sympatric. It is suggested that biotypes in the pea aphid result from annual adaptations to various species of leguminous host plants and therefore other characteristics of the biotypes may vary from year to year. For this reason, only fundatrices and their immediate offspring which have not been subjected to this selection should be used as test organisms in assaying plants for resistance to pea aphids. The use of a biotype of a single year for screening plant varieties may lead to the production of varieties which are highly acceptable to other biotypes.

Parasitism, infertility, and death of fully developed first-stage larvae in eggs (pharate larvae) were the egg mortality factors encountered during a 1967–69 study on the bionomics of the forest tent caterpillar, Malacosoma disstria Hübner, in northern Minnesota. There was no significant difference in the average yearly per cent parasitization and infertility per egg mass; these ranged from 7 to 10% and 1 to 3%, respectively. There was a year to year difference in pharate larval mortality. It ranged from 39% in 1968 to only 9 and 3% for 1967 and 969. Studies showed that egg masses had a tendency to be either nearly complete y hatched or unhatched only in 1968. The variation in pharate larval mortally in these studies suggests qualitative differences in the population. The pharate larval mortality has the potential of influencing population trends of the forest tent caterpillar.