Twelve species are recognized in the abietina group of Pristiphora. A key to species and illustrations of the lancets and penis valves are presented. Only P. erichsonii (Hartig) is holarctic in distribution. P. gerula (Konow) is re-established as a species since it is not a variety of P. saxesenii (Hartig). A new species P. thalenhorsti is described. The name P. takagii is proposed for laricivorus Takagi nee Brischke.

Late-stage gypsy moth larvae, Porthetria dispar (L.), orient by polarized light in woodland openings. Activity of larvae was greatest before 1030 h and after 1400 h Eastern Standard Time, when plane-polarized sky-light was stronger and ground surface temperatures more moderate than during midday. Larvae in the opening were attracted to vertical objects up to 3 m distant at cardinal points closest to their path of orientation but much less to the cardinal points furthest away. Most larvae move in a north to northeast or south to southwest direction at abroad angle to the direction of the sun’s rays.

A new species, Apanteles mahoniae, has been reared from Coryphista meadi Packard, a geometrid feeding on Oregon grape (Mahonia spp.) in the West (British Columbia, Idaho). It is described and differentiated from its close relatives in the glomeratus group.

The synthetic plant growth regulator indolebutyric acid delayed pupation, produced lighter pupae, and interfered with the larva-to-pupa molt of the western tent caterpillar, Malacosoma californicum pluviale (Dyar), when it was mixed with water (0.1 g/1.) in which cut foliage for rearing the larvae was kept. Treatment of very young larvae led to adults that produced more and better eggs than the controls. Treating older larvae produced antigonadotrophic effects.

Using explosives, 93 grand fir were examined for root decay and bark beetle activity. Ninety-six per cent of the trees attacked by bark beetles also had root rot. From the data it appears that root disease is an important factor in predisposing fir to attack by bark beetles. Significant relationships were found between the presence of root decay and both the incidence of beetle attack and the number of attacks. No such relationship could be found concerning the success of beetle attacks. The question of bark beetles as vectors of root disease was not considered.

An investigation was made of the impact of a series of environmental catastrophes upon herbivore population regulation through density-dependent genetic feedback interactions with simulated plants. Mean density and amplitude of fluctuation of the herbivore in the control system (only susceptible alleles in the plant population) were higher than in the genetic feedback system (3 resistant alleles and 3 susceptible alleles in the plant population). Mean density and amplitude of fluctuation of the herbivores in the catastrophic system (only susceptible alleles in the plant population and the herbivore population subject to a series of environmental catastrophes) were lower than in the control and genetic feedback systems, but both mean density and amplitude of fluctuation were higher than in the genetic feedback and catastrophic system (3 resistant and 3 susceptible alleles in the plant population and the herbivore population subject to a series of environmental catastrophes). The results of this experiment suggest that genetic feedback can exert a controlling influence in population dynamics even in systems where environmental catastrophes are a common occurrence.

Evidence from studies in large field cages indicated that odor from virgin male apple maggot flies, Rhagoletis pomonella (Walsh), was attractive to virgin females. Whether the principal role of this odor in mating behavior is in fact that of a female attractant or rather that of an aphrodisiac is uncertain and awaits further study.

The fecundity of apple maggot females was significantly greater (P <.05) on apple than on black ceresin wax domes. Eggs/female laid in apple varied from 24.8 to 318.1 and that in domes from 0.4 to 27.5. Mated females did not lay significantly more eggs than virgins and those confined in groups did not lay significantly more than those confined individually. These findings do not concur with those reported in the literature.