All, postembryonic instars of Hoploseius tenuis n. sp. are described and illustrated. This species is numerous in the pores of coniferous bracket fungi where it presumably feeds on the fungus. Discussed are: the relationship of this species to congeners, and the modification of the generic concept; the ontogeny of the body and leg setation, which includes larval, pustlarval and regressive deficiencies, and retardation; and the ontogeny of body elongation and its effect on the positions of setae. The adult morphology and setation of H. tenuis is briefly compared with that of an elongate digamasellid, Longoseius cuniculus Chant.

Three species of Chlamydatus Curtis described as new are: artemisiae, auratus and knighti.

Seventeen other species recognized from North America are: arcuatus Kngt., associants (Uhl.), brevicornis Kngt., fulvipes Kngt., manzanitae Kngt., monilipes Van D., montanus Kngt., obliquus (Uhl.), opacus (Zett.), pallidicornis Kngt., pulicarius (Fall.), pullus (Reut.), ruficornis Kngt., schuhi Kngt., suavis (Reut.), uniformis (Uhl.), and wilkinsoni (D. & S.). Chlamydatus opacus (Zett.), is recorded for the first time from North America. Chlamydatus apiatus (Uhl.) and C. fumidus (Uhl.) are transferred to Plagiognathus Fieb., new combination. Genus Strophopoda Van D., formerly considered a synonym of Chlamydatus is reinstated to contain Strophopoda aprica Van D. Species are keyed and male genitalia are figured.

To use gizzard analysis quantitatively, in the assessment of bird predation on insect populations, information is needed on the time that identifiable remains of the prey can be found in the gizzard and on the rate at which these remains disappear. The digestion rate, measured by the disappearance of mandibles or cremasters, has been studied for larvae and pupae of the spruce budworm, Choristoneura fumiferana (Clem.), when eaten by the olive-backed thrush, Hylocichla ustulata swainsoni (Tschudi).

Six field colonies and four laboratory colonies of bumblebees were used in a marking experiment during the summer of 1964 in Wisconsin to study the seasonal size increase of the workers. Mean sizes of weekly age groups differed significantly. The workers gradually increased in size in healthy colonies. In colonies disrupted by parasitism or transfer from the field to the laboratory, consecutive age groups of workers were- significantly smaller. After a period of adjustment, the colonies transferred from the field to the laboratory resumed the normal pattern of worker size increase.

Geomyza nubilipuncta n. sp. and G. envirata n. sp. are described from Japan and China respectively. The wing and terminalia of G. advena Frey, from Japan, are figured. A key to the three species is presented.

Capacity to adjust to variable resources of food is a useful criterion for assessing the regulatory influence of predators on the population of prey. Anatis mali Auct. was better adapted than Coleomegilla maculata lengi Timberlake to tolerate a shortage of food. When the food supply was increased, survival and adult weight increased in both species – adult weight to a much greater extent in A. mali than in C. maculata, and developmental time decreased in A. mali, but was unchanged in C. maculata. C. maculata was better able to withstand regularly occurring periods of intermittent feeding than a shortage near the end of its development.

The conversion ratio of third-instar A. mali larvae and the growth rate of C. maculata larvae were higher when individuals were fed on Acyrthosiphon pisum (Harr.) than on Rhopalosiphum maidis (Fitch). Between the minimum food requirement and the maximum quantity eaten, the conversion ratio of A. mali decreased whereas that of C. maculata remained constant except at the highest quantities of food where the rate of intake increased and the ratio decreased. Relative food intake rate is an accurate criterion for comparing stages and species of predators that are fed on various foods.

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.

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.

The effect of any mortality factor on population trend is influenced greatly by other factors that operate contemporaneously within the same age interval, and by the extent to which it interacts with these other factors. A general equation which makes provision for different degrees of interaction is proposed as a simplified first step in the study of interaction, and some theoretical examples are presented to illustrate the importance of the interaction coefficient. Methods for obtaining estimates of the coefficient, both through statistical inference from field population data and through direct observation and experimentation, are discussed.

Four species of woodpeckers (family Picidae) are definitely known to be predaceous on the western pine beetle in the Central Sierra Nevada Mountains in California. These are: Dendrocopus villosus, Dendrocopus pubescens, Dendrocopus albolarvatus and Dryocopus pileatus. The red-shafter flicker (Colaptes cafer, Picidae), creepers (Certhiidae), nuthatches (Sittidae), and flycatchers (Tyrannidae) are thought to be predators on the western pine beetle.

Predation by woodpeckers reduced the western pine beetle population by (a) actual consumption of 31.8% in two generations studied, and (b) by increasing parasite densities in the order of 3.85 factor. The increase in parasite density was believed to have been caused by bark removal to a near uniform thickness enabling a higher parasitism by those parasites with short ovipositors, such as Cecidostiba and Roptrocerus spp.

One adverse effect of woodpecker predation was a reduction or a depression of insect predation. Highly mobile insect predators may have been driven away by woodpecker activity, actually consumed, or both.

Bark flakes, chipped or pried off by the woodpeckers during their feeding activity, contained but few insects and it is doubtful that these could survive on the ground and reach the adult stage.

Maneb (manganous ethylene bisdithiocarhamate) applied topically to Oncopeltus fasciatus nymphs causes death after 7 to 10 days. The gross symptoms of intoxication, histopathology and effect on oxygen consumption are described. Activities such as feeding and walking are slightly reduced after 24 hours and completely inhibited after 3 to 4 days. The tissues most severely affected by the treatment are the secretory cells of the mid-gut epithelium and the cells of the Malpighian tubules. These at first show extreme vacuolization, reduction of the size of cell nuclei and finally cytolysis. Oxygen consumption in vivo is reduced by the treatment.

Larvae and adults of Haplothrips faurei (Hal.) that prey on the tetranychid mites Panonychus ulmi (Koch) or Bryobia arborea Morgan and Anderson attacked mainly the eggs. When no eggs were present, they attacked the motile stages of the mites but their growth and oviposition were slowed. Adult thrips that fed on winter eggs of the tetranychids lived only a short time, unless they also had access to peach leaves. The mite Aculus cornutus (Banks) and fresh pollen of Chenopodium album L. were eaten by H. faurei; pollen was less satisfactory than tetranychid eggs for growth and oviposition. Adults lived for long periods on leaf juices alone.

One larva ate an average of 143 summer eggs of P. ulmi during its developmental period of 8 to 10 days at 24 °C. An adult ate an average of 44 eggs per day at 24 °C. when fed ad libitum.

Females did not fly when fully fed and ovipositing, but they did so during the preoviposition period and after a short period of starvation.

Most individuals of all stages of H. faurei were on the twigs, in crevices find other places of concealment on peach trees, bur a greater proportion of individuals were on the leaves of apple and plum. This difference in distribution was attributed to differential effects on behaviour by the glabrous foliage of peach and the pubescent foliage of apple and plum. The presence of H. faurei on twigs complicated population sampling in peach orchards.

The egg was the stage most sensitive to low humidity, but there was no evidence that humidity limited the population in orchards.

H. faurei was usually scarce in spring. Later, its numbers usually increased with those of the mites and it may have retarded growth of the mite populations, but its most obvious effect was the destruction of winter eggs in the fall.

The ridingsiana group of the genus Euxoa is defined, and the eight constituent species are distinguished by means of a key. Euxoa macrodentata, most closely related to Euxoa cooki McD., is described as new. Euxoa exculta (Sm.) and its nominal subspecies criddlei Sm. are synonymized with Euxoa perpolita (Morr.), and Euxoa perolivalis manitobana McD. is raised to specific rank.

The oviposition and fecundity of field- and lib-reared specimens of the black-headed budworm, Acleris variana (Fern.), were studied. Each female produced from 13 to 179 eggs. Those from field-collected pupae averaged B6.5 eggs in 1963 and 86.7 in 1964; those reared in the laboratory produced significantly fewer. Forcing late-instar larvae to feed on old foliage did not reduce fecundity significantly. Individuals with an early seasonal development produced more eggs than those with a late seasonal development. The regression of pupal size on fecundity was significant at the 1% level. Because the correlation coefficient for the relationship was low (0.48), pupal size provides only a rough estimate of expected fecundity.