The oviposition behavior of Exenterus amictorius Panzer, an introduced parasite of pre-spinning eonymphs of the Swaine jack pine sawfly, Neodiprion swainei Middleton, was studied in a series of field experiments over a 5-year period in the Province of Quebec. The ability of this parasite to discriminate against hosts with previously deposited progeny varied significantly: discrimination was lacking at the beginning of the host’s spinning period, but was rapidly acquired and persisted to the end of the spinning period. The relationships were described by negative power functions of the form Iδ = aX−b, where Iδ = Morisita’s Index of Dispersion, and X = the number of days from the beginning of the host’s spinning period. The response of E. amictorius to changing host densities, however, was positive at all host densities and described by functions of the form Y = aXb, where Y = number of parasite progeny per host and X = number of hosts dropping into funnel traps at 2-day intervals during the spinning period. Over 67% of the variation in the number of progeny deposited by E. amictorius during a field experiment in 1969 was explained by changes in adult parasite density, and an additional 19% by changes in host numbers. This indicates strongly that the observed change in discrimination against previously deposited progeny bears no direct relationship to either host or parasite density. It was suggested that the change might be influenced either by a reduction in the parasite’s egg complement in time, or by an associative learning process.

The density response of an indigenous parasite, Exenterus diprionis Rohwer, was comparatively much weaker and it seemed to lack the adaptive changes in discrimination against previously deposited progeny possessed by E. amictorius. Although attacks of the one species occurred independently of the other, in the event of multiparasitism E. amictorius always survived because of its faster rate of development in the host. The role of discrimination and of density response in the dominance of E. amictorius among the Exenterus spp. attacking N. swainei, and its successful establishment on a variety of North American diprionids, is discussed.

Laboratory-bred rats and mice fed heavy doses of the poxvirus of the spruce budworm showed no ill effects and made normal weight gains as compared with controls over a period of 8 weeks, and no deaths occurred in the treated groups. Laboratory and wild mammals exposed to aerial spray in open-topped cages similarly showed no adverse effects. Population densities, fecundity, and other pertinent life history parameters of small mammals and birds were studied relative to treatment of a forest with the poxvirus for control of spruce budworm. There were no observable interactions between these small vertebrates and the virus. It is concluded that, from the standpoint of homoiothermic vertebrates, the virus is a safe insecticide.

A sequential sampling method for egg clusters of the Swaine jack pine sawfly, Neodiprion swainei Middleton, is described.

Overwintering eggs of Porthetria dispar increase their capacity to supercool during exposure to non-lethal conditioning temperatures. Measurements of supercooling points of eggs collected in Quebec and Massachusetts indicate that the gradual movement of the insect north and west from the initial point of introduction into North America has not been accompanied by natural selection for a more cold-hardy population. The protection afforded eggs by cold-hardening is, however, greatly enhanced by the placement of egg masses, typically at or near ground level, where they are subject to maximum insulation by snow cover.

Examination of climatic regimes within the current area of distribution of the gypsy moth in Eurasia indicates that temperature may not be a key factor limiting its northward spread. In central Canada, in the presence of abundant snow cover, the insect may spread as far north as suitable food plants exist. This would favour extension of the range of the gypsy moth throughout the Great Lakes – St. Lawrence Forest Region and much of the Boreal Forest Region of Ontario and Quebec south of James Bay.

The antibiotic effects of foliage extracts of some forest trees on commercial Bacillus thuringiensis (Berliner) var. galleriae were studied with a view to determining whether or not such substances might be inhibitory to development and multiplication of ingested bacteria.

The results indicate that ethyl acetate and petroleum or ethyl ether extracts of the trees tested were particularly inhibitory to the bacteria. Of 24 pure terpenes tested, pinene, pulegone, menthone, 4-terpineol, citral, citronellol, and linalool were highly inhibitory to the production of spores and crystals by the bacteria.

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.

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.

Fecundity and egg survival had inverse linear relationships with increasing evaporation potentials expressed as vapor pressure deficits. With an increase of vapor pressure deficit from 4 to 24 mm Mg at a favorable temperature of 25.5 °C, mean fecundity could be reduced from 130 to 51 eggs and egg survival from 90% to 20%. Optimal laboratory physical conditions for egg production consisted of a low evaporation rate of less than 9 mm Hg vapor pressure deficit but short of a saturated atmosphere at a room temperature of 25.5 °C. One hour daily exposure of eggs to high temperatures up to 39 °C did not cause a significant increase in egg mortality. In the field there was no difference in fecundity of females between plots in damp western Washington and dry central Oregon (pine region). Egg mortality was always higher at the central Oregon plot, presumably because of higher evaporation rates. Since high vapor pressure deficits are common occurrences during the growing season in most of the pine region, it is possible this factor could limit Rhyacionia buoliana populations in some of these areas.

Codling moth populations on natural apple fruit trees scattered throughout Nova Scotia are compared with those in commercial orchards. In natural fruit, failure of crop, crop size, degree of isolation, amount of crowding by native trees, and natural enemies determine the level of codling moth numbers. Young commercial orchards require artificial control measures within a few years of first bearing fruit to prevent severe crop losses. In older commercial orchards natural controls require an occasional assist by chemical treatment to contain the codling moth below economically tolerable levels. Such treatment is applied to interfere as little as possible with known natural controls.

Observations were made during 1967 to 1969 at Ithaca, N.Y., supplemented by collections at New Cumberland and Carlisle, Pa., on arthropods associated with fungi occurring on alfalfa, Medicago saliva L. Five species of Coleoptera, two species of Diptera, one species each of Collembola and Psocoptera, and nine species of Acari were reared or collected consistently from fungus-covered alfalfa leaves, stems, and seed pods. Attraction to fungi on the plants, principally Alternaria sp., accounted for the presence on alfalfa of arthropod species that normally might be considered as accidentals or visitors. The mycetophagous species thus contributed to the richness of the alfalfa fauna. Immature stages of several species were collected only in late fall or on 3- or 4-year-old plants. The possible role of the fungus-feeding species in seasonal changes in the alfalfa fauna and changes in the fauna in successive years is discussed.

The sex ratios at emergence of some Chironomidae from ponds in the Hazen Camp area (81°49′ N., 71°18′ W.) are given from trap records for a number of seasons.

In Tanypodinae and Chironomini there are apparently about equal numbers of the sexes; in Tanytarsini and most Orthocladiinae females consistently outnumber males, often forming 60% or more of the total emergence. These findings are discussed: the presence of facultative parthenogenesis in some species is thought to be likely.

Experiments were designed to determine the effects of low doses of some insecticides on the viability and physiological characteristics of commercial Bacillus thuringiensis (Berliner) as a prelude to studies on the susceptibility of lepidopterous forest defoliators to mixtures of bacteria and insecticides.

The results show that the insecticides tested had no effect on viability or physiological integrity of the bacteria.

Bacteria–insecticide combination effects varied from strongly antagonistic to strongly supplemental depending on insecticide or Thuricide® formulations and concentrations and on the relative susceptibility of the test species to either agent applied separately. Pyrethrum at 10−3 was highly potentiating to BT at 10−1 against third instar Halisidota argentata. Among Hyphantria cunea, a supplemental effect always resulted from combining Thuricide® at 10−2 with low concentrations of malathion, phosphamidon, or pyrethrum.

There was generally a drastic reduction in feeding activity among BT-treated insects and a further reduction among BT-chemical-insecticide-treated ones compared with controls.

Based on rate of larval development, the confused flour beetle, Tribolium confusum (Duval), consistently differentiated among selected cereal cultivars provided as food. Although variations occurred in ranking order from test to test, some cultivars always permitted faster larval development than others. There was good correlation between results from tests with the beetles and from those with chicks fed the same rations. Addition of minerals and micronutrients to the cereals changed the nutritional value for the beetles but the extent of change was not uniform among the cultivars.

Carbofuran was applied to three hayfields at a rate of 0.56 kg/ha in early June. This caused significant reductions of Thysanoptera, phytophagous Coleoptera larvae (including the alfalfa weevil, Hypera postica (Gyl.)), and Cicadellidae. It caused similar reductions in Araneida and parasitoids. The differences between treated and untreated plots were no longer significant by September. Carbofuran did not significantly affect the yield of air-dried hay or of crude protein.

Dichrooscytus elegans Uhler is redescribed and its status discussed. Four new species of Dichrooscytus are described: minutus, flagitiosus, and taosensis from New Mexico, and texanus from Texas. Male genitalia of the species are illustrated, host plants are given, and relationships to other species in the genus are discussed.

Microctonus stelleri Loan is described as a new species. This euphorine braconid occurs in France, Germany, Sweden, and Russia. It is umvoltine and its only known host is the alfalfa weevil, Hypera postica (Gyllenhal). In the spring the mature parasite larva issues from the overwintered adult host and forms a white cocoon in the ground litter. In about 2 weeks the adult parasite emerges, mates, and oviposits in larva of the alfalfa weevil. The parasite egg hatches and the first-instar larva remains within the host until the following spring. In northern France M. stelleri was the dominant parasite in overwintering adults of H. postica. Parasitism ranged from 0 to 13% though it was usually less than 6%. Laboratory studies showed that M. stelleri females live longer, have a higher rate of oviposition, and parasitize more hosts than females of M. colesi Drea, a parasite of the weevil in the United Slates. A technique is described for the recovery of M. stelleri from adult alfalfa weevils. From 1966 to 1970, 4387 parasites were imported from France and released at 24 localities in the United States.

Nine new species of Dichrooscytus Fieber are described from North America: aztecus and toltecus from Puebla, and mexicanus from Durango and Coahuila, Mexico; longirostris, ochreus, and rubromaculatus from California, brevirostris and dentatus from Arizona, and alpinus from Colorado. Male genitalia are illustrated, host plants are given, and relationships to other species in the genus are discussed.

Adult black flies were trapped at the townsite of Deep River from the early emergence of Prosimulium spp. (approx. 21 May) through to the late summer decline of Simulium spp. (in August). "Sticky" traps employing CO2 as an attractant were located at five sites throughout the town; in addition a trap was positioned at a "control" site outside the town limits near a heavily forested area. The overall numbers increased rapidly in early June, remaining at high levels until the first week in July, by which time over 110,000 flies had been captured. The numbers of flies recovered both within and outside the town fluctuated widely with weather conditions, seemingly influenced by precipitation. In the town, three centrally located traps captured only half as many adults as two traps near the southerly limits, where a small stream flowed through light forest. The control trap showed that black flies were at least 10 times more plentiful outside Deep River. Three insecticide applications did not have any measurable effect on fly numbers. The predominant local species is Simulium venustum Say.

Scolytids were collected from snowfields above timberline in Oregon and Washington. The most productive location was Collier Glacier on Middle Sister Mountain, Ore., where 334 specimens representing 20 species were collected on 4 August 1968. Collections from seven mountains comprised 476 specimens, 12 genera, and 26 species. Hylastes nigrinus (Mann.) made up 63% of the specimens collected. The collections demonstrated that bark beetles had been dispersed vertically and horizontally thousands of feet from the nearest possible source. Phloeosinus chamberlini Blkm. was found 15 miles from the closest known host tree. Behavioral and meteorological factors involved in the dispersal of scolytids to snowfields are known only circumstantially. Certain species are thought to fly skyward initially. Some individuals presumably are carried aloft by warm updrafts and their fallout occurs when the air becomes too cool for flight.