A variety of field sampling procedures were used to estimate population levels of the gypsy moth, Porthetria dispar (L.) (Lepidoptera: Lymantriidae), and the following natural enemies: Apanteles melanoscelus (Ratzeburg) (Hymenoptera: Braconidae), Blepharipa scutellata (Robineau-Desvoidy) (Diptera: Tachinidae), and Calosoma sycophanta (L.) (Coleoptera: Carabidae). Regression analyses indicated, among other things, that gypsy moth egg mass counts were not good indicators of tree defoliation, but that defoliation and number of gypsy moth larvae on branch terminals were correlated. Estimates of adult abundance of A. melanoscelus and B. scutellata were negatively correlated with estimates of numbers of immature parasitoids. Numbers of gypsy moth larvae parasitized by A. melanoscelus were positively correlated with numbers of A. melanoscelus cocoons sampled. Numbers of adult C. sycophanta were not correlated with larval numbers of this insect. It was concluded from these results that the procedures used to estimate numbers of natural enemy adults were not entirely adequate, but may be useful for supplementing other sampling methods.

Pinus rigida trees exposed throughout the study to chronic gamma irradiation were inventoried to determine the intensity of attack by the bark beetles Ips grandicollis and I. calligraphus. Beetle developmental success was determined from bark samples by estimating the percentage of the cambial surface utilized. Trees killed by high radiation doses were attacked by the beetles even though radiation exposure proved lethal (> 500 r/day). In dead trees receiving lower doses adults survived but progeny were killed during different stages of development, depending on the dose rate. Developmental success was less on the exposed side of each tree than on the shielded side. Species with short life cycles have a survival advantage over those that have a long life cycle when exposed to chronic irradiation.

The parasitic juveniles of mermithid nematodes attack a variety of hosts from 15 insect orders (Welch 1963, 1965). Little is known of the extent to which they are parasites of Miridae. Menzel (1922) and Cobb et al. (1927) recorded parasitism of the bug Helopeltis theivora Waterh. by Mermis sp. and by Agamermis paradecauta Steiner, respectively. A related mirid, H. antonii Sign., was reported parasitized by Mermis sp. (Menzel 1922), and by A. paradecauta and Hexamermis microamphidis Steiner (Steiner 1925). Recently King (1969) found that the mirids Sahlbergella singularis (Hagl.) and Distantiella theobroma (Dist.) were hosts of the genus Mermis Dujardin.

Populations of Tribolium castaneum (Herbst) exposed to sublethal doses of irradiation (0.5–4.0 krad) each generation for as many as 25 generations had decreases in reproductive capacity and increases in sterility that were positively correlated with the size of the dose per generation, but not with the number of ancestral generations treated. Exposure of the selected populations to an acute dose of irradiation (2.0 krad) revealed no increase in tolerance to irradiation even after 25 generations of selection. Radioresistant populations would probably not arise from fertile survivors of irradiation disinfestation of bulk grain.

Two types of field bioassays of the relative attractiveness of various pheromone sources to Ips pini were conducted at Wanakena, N.Y., and at Warrensburg, N.Y. In the first test, the numbers and sex ratios of beetles responding to boring males from New York, Idaho, and their F1 and backcross hybrids graded down in the order of "blood relationship." The intermediate attractiveness of hybrids indicates that hybrids produce pheromones of both parents. In the second test, New York males reared in white pine attracted greater numbers of beetles than those reared in red pine and beetles boring in white pine were more attractive than those boring in red pine.

Adult emergence of Simulium decorum and Simulium tuberosum was reduced or completely inhibited in air-agitated stream water by 0.1 p.p.m. slow release formulations of insect growth regulators. Abnormal pupae were produced when S. decorum larvae were exposed to 5 p.p.m. R20458-4E.

Extracellular hook electrode recordings were made of activity in the ventral nerve cord of the larvae of Orthosoma brunneum (Forster) during application of 30% CO2 to the head region. The work involved bilateral amputation of the tip segments of antennae, maxillary palps, and labial palps so that each specimen bore only one intact pair of the three sensory organs. Larvae with only intact antennae exhibited no response to CO2 in the ventral nerve cord; larvae with only maxillary palps did respond; larvae with only labial palps did respond, but less noticeably. Maxillary and labial palps are sites of CO2 reception in O. brunneum.

The visual–acoustic signal system of Dissosteira carolina (L.) is described from field and laboratory observations. The form and occurrence of seven visual signals, seven visual–acoustic signals, and three behaviour patterns with possible signal function are described. The functions of these signals are discussed and a new functional category (interaction terminating) is proposed.

Macrosiphum euphorbiae (Thomas) was fed on artificial diets containing coumarin, phloridzin, kinetin, kinetin riboside, royal jelly, ALAR-85, and chlorogenic acid. Incorporation of chlorogenic acid in the artificial diet improved the growth of the potato aphid which was studied up to 17 generations. Coumarin and kinetin riboside at higher concentrations inhibited growth whereas phloridzin prolonged the developmental period of aphids in the second and third generations. The inhibitory effect of ALAR-85 and kinetin became apparent in the third and second generation nymphs, respectively, which did not reach the adult stage. Addition of royal jelly neither enhanced growth nor fecundity of M. euphorbiae.

The sex-pheromone-producing gland of the eastern spruce budworm, in addition to producing the sex attractant (E)-11-tetradecenal, has been shown by gas chromatographic and mass spectral data to contain (E)-11-tetradecen-1-ol, a known inhibitor to the sex attractant.

Single 15-min injections of 0.18 to 0.24 p.p.m. of methoxychlor as an emulsifiable concentrate into the Saskatchewan River removed 75 to 99% of the larvae of Simulium arcticum Mall. from 23 to 34 km sections of the river. Stronger concentrations (0.30 to 0.31 p.p.m.) eliminated about 98% of the larvae from rapids 64 km distant and an estimated 46% at a distance of 139 km. Other kinds of aquatic larvae in exposed sites were also affected: Plecoptera to about the same degree as the Simuliidae, followed by Ephemeroptera, Trichoptera, and Chironomidae (least affected). Larvae in sand were not affected. Populations of Chironomidae, Trichoptera, and Ephemeroptera in many sites were completely restored within 7 to 14 days after a single treatment. Fish were apparently unharmed. Residues were negligible and short lived.

Potential outbreaks of S. arcticum were averted by all of the experimental injections of methoxychlor except that of 26 May 1970. In this test an outbreak that killed four animals occurred because a 15-min, 0.207 p.p.m. dosage eliminated only about 23% of the black fly larvae in an adjacent portion of the river.

Under field conditions, as well as in the laboratory, the critical photoperiod for the formation of sexes in the pea aphid, Acyrthosiphon pisum (Harris), is from 13 h and 15 min to 13 h and 17 min. The fecundity of this aphid on the pea variety Lincoln under field conditions is similar to that obtained in the laboratory (maximum 66 ± 10 and a minimum of 35 ± 12 individuals).

Up to 47% males and 80% oviparous females were produced under field conditions. This percentage is less than that obtained in the laboratory where 57–63% males and 90% oviparous females were produced.

Xylem sap tension, an indication of moisture stress, was compared in foliated twigs of white fir infected by the mistletoe, Phoradendron bolleanum subspecies pauciflorum, and in paired, uninfected fir at the lower, mid-, and upper crown level. The upper boles were examined for fir engraver attacks. Reproductively successful attacks containing little or no host oleoresin were found in the infected fir, while only a single unsuccessful attack filled with oleoresin was found in the uninfected trees. Mean moisture stress in the upper crowns of most of the infected fir exceeded that in uninfected trees in all paired comparisons except one with a light infection. No differences in mean moisture stress between infected and uninfected trees were found at the lower and mid-crown levels.

Mites collected from 69 Larus delawarensis Ord nests on Granite Island, Lake Superior, northwestern Ontario, during the summers of 1972 and 1973 showed phenological relationships with the breeding cycle of the gulls. The populations of five selected mite genera varied in relation to nest initiation, egg laying, and egg hatching periods of the gulls. Moisture within the nests significantly affected mite population densities, whereas nest density did not.

Three types of traps were tested in 1969 and 1970 for collecting pupae of the eastern hemlock looper, Lambdina fiscellaria fiscellaria (Guen.). Highest numbers of pupae were obtained with burlap traps made from 2-ft-wide bands wrapped around trunks of infested trees. The proportion of the pupae in the burlap traps was estimated. Some of the potential uses for pupae collected by the method are mentioned.

Field tests demonstrated the attractiveness of several compounds to the olive fly, Dacus oleae Gmel.; a correlation with far infrared absorption bands was derived; and dl-homocysteine thiolactone hydrochloride was tested because of its conformity with this pattern. Field tests confirmed the predicted attractiveness of this and a few other compounds, and also an anti-attractant property in menthol and in butyl butyrate.