Log preference of the ambrosia beetle, Trypodendron lineatum (Oliv.) (Coleoptera: Scolytidae), was studied by flight traps, attack density counts, and forced attacks, on 200 Douglas fir felled over a ten-month period. During heavy spring flights in late May, the beetles attacked logs from the August through January fellings, but not those cut February through May. At the end of the first brood-rearing period, parts of logs protected by plastic sheeting from earlier flights were attacked in this same pattern. Beetles confined on logs at different times attacked in essentially the same way as free beetles. It is concluded that felling date greatly influences subsequent attack. However, there was considerable variability in attack within groups of trees cut the same dates. Furthermore, attack on very short (1- and 3-foot) sections from the February fellings, when the corresponding logs were unattractive, showed that a factor other than time of felling also influenced log attractiveness. Some information was secured on flight and attack of other scolytid beetles in relation to felling date of logs.

Large numbers of Oriental fruit moth adults were successfully tagged (500 or more counts per minute) by holding them for 24–48 hr. in cages provided with cotton wicks moistened with a water-solution of P32 at 20 microcuries per millilitre. The addition of sugar to the tagging solution did not increase its effectiveness. Approximately 80% of the total radioactivity of the tagged moths was internal due to ingested liquid and the remainder was on the surface of their bodies; 73% of the total was in and on the abdomen. The loss in radioactivity of tagged moths in 1–6 days was 2.2–4.7 times greater than the theoretical loss due to isotope decay alone. The highest rate of loss occurred during the first day, probably through excretion before the P32 was absorbed from the digestive tract. Egg laying contributed to loss of radioactivity. Though water and liquid bait removed some P32 from tagged moths this did not result in appreciable contamination of other moths trapped in the liquids.

Attempts to tag large numbers of moths (400–1000 per cage) for release and recovery experiments were only partially successful as the radioactivities attained by individual moths varied widely at different times and from cage to cage, even under the same environmental conditions. This appeared to be partly due to differences in the feeding behaviour of different batches of moths and it may have been influenced by the conditions under which they were reared.

Observations on the occurrence of Camnula pellucida (Scudder) on native grasslands in Saskatchewan indicated that such areas did not support large populations of this species except on the margins where these were adjacent to cereal crops. This supports the view that large-scale infestations arise when both a food habitat (cereals) and an oviposition habitat (short grass) are readily available to the insects.

The density and spatial relationship between the wasp parasite, Nasonia vitripennis, and the housefly host, Musca domestica, were investigated. As parasite dispersion decreased in a defined space, parasitism increased from 30 to 76% and host survival decreased from an average of 65.0 to 18.9%. The number of host pupae producing parasite progeny and the survival of host pupae decreased as the proportion of small host pupae increased. With host numbers increasing and parasite numbers constant, the mean number of eggs deposited per host increased significantly from 31.25 to 87.25 and the number of stings increased from 2.25 to 8.00. As parasite density increased and host number remained constant, the number of hosts which were nor attacked declined from a mean of 2.2 with 1 parasite to none with 32 parasites. Host survival declined from about 50% at the 1:8 ratio of female parasites to hosts to no survival at the 2:1 ratio.

The Rhyacophila coloradensis complex is discussed and a new species, amabilis, is added to the group. Two new species of Rhyacophila are described from California, spinata and ardala. Four new species of Limnephilus are described from California, bucketti, catula, atercus and neoacula; the first three represent interesting variations from described species. Several Limnephilus females are associated with the described males.

The status of the genus Plega is discussed and a preliminary survey of the North American species is presented. Plega yucatanae, a new species reared from the cells of Megachile exaltata Smith, is described and compared with its near relatives. The immature stages are described and biological information is given.

Laboratory tests revealed that female Douglas-fir beetles, Dendroctonus pseudotsugae Hopkins, boring in logs of both host and non-host species produce a volatile substance that both attracts and arrests adult beetles. Male arrestment provided a reliable method for laboratory bioassay of volatile substances. Field tests were devised to show the attack, the attraction produced, and the broad development in six tree species: Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco; western larch, Larix occidentalis Nutt.; ponderosa pine, Pinus ponderosa Laws.; western hemlock, Tsuga heteropbylla (Raf.) Sarg.; western white pine, Pinus monticola Dougl.; and grand fir, Abies grandis (Dougl.) Lindl.

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.

Mycophila speyeri Barnes is presently the most important mushroom-infesting cecid fly in Pennsylvania. Larval paedogenesis is the main means of reproduction (used by this species). Adult cecid fiies and sexual reproduction arc rarely observed in mushroom growing houses. The higher temperatures of spawn-run (70 ° to 75 °F.) are very favorable to paedogenetic reproduction of M. speyeri. Under these conditions, a generation is completed in about one week and about ten daughter-larvae per mother-larva are produced. The quantity of malt in the culture medium, the age of the spawn, and strain differences in spawn also play roles in the length of a generation and the number of young produced by a mother-larva. The lower temperatures (55 ° to 60 °F.), normal during mushroom cropping, approximately triple the time required to complete a generation. Prevention of cecid infestations during the spawn-run and sanitation to prevent spread, once larvae are present, are important considerations in the control of M. speyeri. Adult cecid flies occur only when populations become crowded on old growing media.

Since the earliest days of this century the interactions of parasitic Hymenoptera that attack the same host species have been reported from time to time in connection with studies on the natural enemy fauna of pest insects. These studies indicate that the synchronous attack by two or more parasitic species on an individual of a host population, multiple parasitism, is of little, if any, importance in the economy of that population, whereas the attack by two or more parasitic species on a sequence of a host’s developmental stages and instars, sequential parasitism, may be highly important, especially from the standpoint of host regulation. Since the host-regulating capacity of a parasite species may vary both seasonally and geographically, sequential parasitism is highly conducive to continuity in the conservation of the host’s food supply, the practical measure of regulative parasitism. The cooperative as well as the competitive aspects of sequential parasitism are discussed. The parasite fauna of the black scale, Saissetia oleae (Bernard), is used to exemplify these aspects of parasitism.

Agelenopsis potteri (Blackwall) spiders that were reared from egg to adult on live prey (Aedes aegypti L.) supplied at different daily rates varied in the rate that they were able to capture prey, grow, and attain maturity. Mortality varied inversely with feeding rates, but some spiders matured at each feeding rate. All spiders matured in seven stages regardless of the rate of feeding. Both sexes were mature following the sixth moult. The rate of prey capture declined sharply in the adults. Males matured about four days sooner than females. A straight-line relationship exists between the rate at which prey were captured and the dry weights of the adult spiders. A straight-line relationship was also found between the numbers of prey captured per day and the daily development of the spider.

The spruce budworm, Choristoneura fumiferana (Clemens), was reared on a synthetic diet. Comparison of two successive laboratory generations reared on synthetic diet and on frozen balsam fir buds showed that diet-fed insects had a higher survival, developed faster, were heavier, mated more successfully, and were more fecund.

This study confirms an earlier finding that the oystershell scale, Lepidosaphes ulmi (L.) is normally controlled in Nova Scotia apple orchards by the aphelinid Aphytis mytilaspidis Le B. and the predacious mite Hemisarcoptes malus (Shimer). The effectiveness of the former may be limited in colder areas by low winter temperatures, and both species are detrimentally affected by some spray chemicals. The evidence presented indicates that either A. mytilaspidis, or H. malus, or the two of them together, may operate as key-factors in regulating the density of oystershell scale populations.

The larva of Orygmophora mediofoveata Hampson is described. It has an unusual combination of features, including modifications of the spinneret, spiracles, thoracic and abdominal setae, and the tenth abdominal tergum. The most striking of these, the heavily armored anal plate, permits ready field identification.

A flightless strain of Drosophila melanogaster Meig. was used with a dry-film bioassay technique for the analysis of dieldrin residues in wheat grain. The flightless fruitflies were much more convenient to handle than a wild strain and the use of a slippery plastic barrier on collecting and sorting dishes avoided the need for immobilising flies by cold or CO2. Experimental evidence is given for the adoption of standardised breeding and handling systems for controlling certain intrinsic factors in the fly population. Also, by controlling such extrinsic factors in the bioassay system as the number of flies per test vial, replication, and holding temperature, a satisfactorily reproducible LD50 of 0.015 μg. dieldrin per vial was obtained. When this technique was applied to the analysis of dieldrin residues in wheat grain, 0.01-0.10 ppm. dieldrin could be conveniently assayed after chromatographic cleanup of a solvent extract of the grain. The accuracy of the bioassay estimates has been confirmed by gas-chromatographic analysis.

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.

Lipids account for approximately eight per cent of the wet weight of Neodiprion pratti larvae. Fatty acids comprise eighty per cent of the total lipids. Approximately seventy-five per cent of the fatty acids are unsaturated and over seventy per cent have eighteen carbons. Four unknowns were characterized as being polyunsaturates of sixteen and eighteen carbons.

A number triangle system is presented which permits determination by simple addition of the Wilcoxon exact-solution numerators to indefinitely large values. Tabulated values of these numerators are included. This approach permits the range of applicability of the exact solution to be extended indefinitely, and has the advantage of requiring only a minimal mathematical background for its understanding. Combinations of these number triangles can be employed to yield exact solutions for samples involving tied ranks.

A new genus of Otopheidomeninae is described, keyed, and based on a new species, Nabiseius duplicisetus. Larvae, nymphs, and females of this mite were found on the abdominal dorsum of a nabid bug, where presumably they are ectoparasitic, as with related species.

Feeding tests in which various components were omitted individually from a chemically defined diet for adults of the parasitoid Exeristes comstockii (Cress.) (Hymenoptera: Ichneumonidae) showed that amino acids, salts, and vitamins were needed for maximal egg production and maximum numbers of eggs contained in ovaries. Omission of fatty acids, ribonucleic acid and cholesterol had no effect. Only omission of vitamins lowered egg hatch. Tests showed that the ovaries could recover from vitamin starvation.