The chorionic architecture including the general and fine structure of the various shell layers and specialized areas in the newly-laid egg of Amathes c-nigrum (L.) is described. The chorion is, primarily, two-layered. The lamellate outer layer, comprising the main bulk of the shell, appears to be very porous over the ventral surface of the egg but much more solid over the lateral and upper surfaces. Here it is traversed by aeropylar canals which convey air to the inner layer. The trabecular inner layer completely surrounds the yolk except in the micropylar area. The micropyles protrude from the inner side of the chorion to form entomicropylar tubes which project towards the yolk. Each is enclosed by thickened vitelline membrane.

The subgenus Chrysocharis s. str. in America north of Mexico consists of 18 species. Of these, six are new: Chrysocharis beckeri, subcircularis, bellincus, clarkae, truncatipennis, and levipectus. The name giraulti is proposed for petiolata Girault nec Förster. Key to species, descriptions, host records, and illustrations are included. Relationships of species-groups of North America and Europe are discussed.

Ceutorhynchus litura (F.) laid an average of 123 eggs per female. Development from egg to adult took about 6 weeks at room temperature, followed by an obligatory diapause of 3–4 months. In laboratory rearings a maximum of only an 8-fold increase over the original breeding stock was achieved in one generation. The weevil was released against the weed Canada thistle (Cirsium arvense (L.) Scop.) near Belleville, Ont., in 1967. Near the centre of the release site on about 400 m2, thistle shoots have decreased to 4% of their former density of about 3–7 shoots per 0.25 m2. Circumstantial evidence indicates that the weevil aided in the spread of thistle rust Puccinia punctiformis (Str.) Rohl.

The European pine shoot moth developed successfully on native lodgepole and ponderosa pines at central Oregon locations. Lodgepole and slow-growing ponderosa pine less than 6 ft in height were most susceptible to damage. Largely because of low winter temperatures, interior British Columbia, northern Washington, northeastern Oregon, Idaho, Montana, Wyoming, Nebraska, and the Dakotas are not likely to experience Rhyacionia buoliana (Schiff.) damage. In contrast, southern Oregon and northern California pine stands are highly susceptible.

Hypopteromalus tabacum (Fitch), Catolaccus aeneoviridis (Girault), Spilochalcis side (Walker), and Spilochalcis hirtifemora (Ashmead) were hyperparasites of the tobacco hornworm, Manduca sexta (Linnaeus), most frequently reared from cocoons of the primary parasite, Apanteles congregatus (Say). The life history of each species was studied and the distinctive features of egg, last larval instar, and pupal stage were described.

In 1969 through 1972 parasitization of the tobacco hornworm by A. congregatus started at low levels in June or July, increasing to nearly 100% by the end of September. A corresponding increase in the seasonal incidence of hyperparasitism was observed, although the level of hyperparasitism never exceeded 85% in any year. Each year S. side and S. hirtifemora were the first hyperparasites recorded; however, H. tabacum was always the most abundant. The number of C. aeneoviridis varied greatly from year to year.

Peak spring emergence of H. tabacum and C. aeneoviridis occurred in April just before that of the primary parasite, A. congregatus, and as this was several months prior to their appearance in tobacco fields a number of possible alternate hosts for the hyperparasites were investigated.

The effects of Abate, Dursban, and Methoxychlor and their diluents on black-fly larvae and on “non-target” stream invertebrates were evaluated by means of cone, rock, Surber, and drift samples. Blackfly larvae were found in many post-treatment Surber samples, although concurrent cone and rock samples often indicated that blackfly larvae were either greatly reduced in numbers or eradicated from the streams. The insecticide diluents (H.A.N, and fuel oil) caused detachment of blackfly larvae from cones, but less than that obtained when insecticide was added.

The heavy post-treatment drift of “non-target” invertebrates in treated streams is indicative of a considerable disturbance to the aquatic invertebrate community. However, post-treatment samples indicated that the “non-target” organisms studied were not eradicated from the streams.

There were several indications that the catch of invertebrate drift was altered by pools, which possibly exerted a delaying action on drifters in the treated streams. Most of the drifting invertebrates found in post-treatment drift nets were dead.

The arthropod fauna associated with deteriorating crowns of alfalfa, Medicago sativa L., was studied at Ithaca, N.Y., during 1968–1969. Four decompositional stages of crowns were delimited, ranging from those of healthy, 1-year-old plants to those of dead plants. A total of 77 arthropod species, including 44 species of Diptera, were reared from the four stages of crowns. Information given for each species includes relative abundance, and associated stage of crown and number of crowns. Adults of several reared species had been collected from alfalfa foliage samples in previous years of study and were species for which the relationship to alfalfa had been obscure and which might in most insect–plant studies have been dismissed as being of chance occurrence or accidental on the plants. However, species breeding within the crowns contributed to the richness of the alfalfa fauna. Because species breeding within the microhabitat of decaying crowns were only rarely found to be associated with other morphological parts of the alfalfa plant, the crown community can be considered as a “centre of action” within the total alfalfa–arthropod community. The possible importance of considering species comprising the crown community in studies on communal stability is discussed.

None of the species of the crown community were shown to be definite primary invaders in crowns of healthy plants, although several reared species have been reported to damage living plant tissue. Many of the species probably were feeding on microorganisms and partitioning the available food resources by feeding preferentially on different classes of microorganisms. The majority of species should be classed as secondary invaders. While mechanical and winter injury probably were the main causes of initial damage to the crowns, feeding activities of the secondary-invading arthropods may have accelerated the process of crown deterioration and further opened tissues of the crown to penetration by pathogens.

The numbers of heat units during a fixed overwintering period and a shifting early larval feeding period for the forest tent caterpillar, Malacosoma disstria Hübner, were calculated from daily temperature data and related to known infestations of this insect in the Prairie Provinces and Ontario. Paired comparisons showed that years with increasing populations had cooler overwintering periods and warmer early feeding periods than did those with decreasing populations. Continuous records for each of 10 climatological stations showed that all known infestations in these areas were preceded by a single year (2 to 4 years earlier) with a relatively cool winter and an unusually warm spring, and that most population collapses were accompanied by cool springs and some by warm winters. The same general pattern prevailed for infestations in southern Ontario, when compared with the numbers of heat units at Toronto for the period 1860 to 1969. Some of the assumptions made during the analyses and the possible use of the results in predicting when and where outbreaks are likely to occur are discussed.

The supposedly cosmopolitan species Nomophila noctuella (Denis and Schiffermüller) is shown to be one of a complex of 12 distinct species, some sympatric, some allopatric, and none ranging over more than three continents. N. noctuella itself has the widest range, extending through most of the Palaearctic and Ethiopian regions, including Madagascar, and into tropical Asia as far as India and Pulo Laut. It also occurs adventively in Hawaii. Two additional endemic species, N. africana n. sp. and N. brevispinalis n. sp., occur in Africa; the Australian species, N. australica n. sp., is endemic but occurs, probably adventively, on Christmas Island. The North American species, N. nearctica n. sp., is distinct from N. noctuella, but, like it, is a migrant and ranges south to northern tropical America. There are six endemic species in South America: N. colombiana n. sp., Colombia; N. heterospila (Meyrick), Andes, transferred from Macronomeutis, which falls as a synonym of Nomophila; N. helvolalis (Maassen), Andes; N. distinctalis n. sp., Peru, Bolivia, and Chile; N. indistinctalis (Walker), central and southern South America; and N. triticalis Berg, Argentina and Paraguay, to which N. squalidalis (Hampson) falls as a synonym. N. incognita Viette, known from a single female from Amsterdam Island, Indian Ocean, is a good species.

Analysis of larval and adult characters, as well as biological data from various geographic populations, indicates that Chrysopa mohave Banks and Chrysopa carnea Stephens represent two strains of a single species and C. mohave is therefore designated a new synonym of C. carnea. The carnea strain occurs allopatrically throughout eastern and midwestern North America and the mohave strain is probably indigenous to California.

The pattern of variation found in larvae and adults from different populations suggests that the carnea strain was secondarily introduced into California where it interbred with the mohave strain. This hybridization resulted in genetically varied populations with predominantly carnea characteristics in California’s Central Valley. Populations of the mohave strain occur in the California foothill and coastal areas because adults of the mohave strain, unlike the carnea strain, can aestivate during the hot, dry summers when food is sparse. Summer irrigation increases the abundance of larval and adult food which the non-aestivating carnea strain needs. It appears that the native mohave strain will compete successfully only in those areas of California which are unmodified by agricultural practices.

Procedures for absolute population sampling of the gallicola migrans stage of the pine leaf chermid on its secondary host are described. This involves determining the mean numbers of gallicolae per fascicle on one twig from each of 29–240 pines per stand and estimating the numbers of fascicles in the stand from the distribution of stem diameters. Patterns and distributions of the gallicolae within trees and stands are discussed with comments on their biological significance.

Seed produced by Fraser fir, Abies fraseri (Pursh) Poir., infested by the balsam woolly aphid, Adelges piceae (Ratzeburg), was compared with that originating from uninfested trees during a cyclic year of heavy seedfall (1969) in western North Carolina. Cones were significantly shorter and seed uniformly lighter and smaller from trees infested by the aphid. X-ray examination indicated the number of full seed from uninfested trees averaged nearly 70% and 42% higher than in comparable seed samples from infested trees. Germination tests indicated viability of seed from infested trees exceeded 32% and that from uninfested trees exceeded 75%. An important factor affecting survival of seed from the two sources appeared to be the relative susceptibility of seed to attack by Megastigmus specularis Walley. Almost 28% more seed were destroyed by these seed chalcids for aphid-infested trees than for uninfested trees.

Telenomus reynoldsi n. sp. (Scelionidae: Telenominae) is described as an egg parasite of Geocoris punctipes Say and G. pallens Stål in California. The parasite has been recovered from cotton fields at Thermal and Indio, and from strawberry fields at El Toro, California. Additional material deposited in the U.S. National Museum of Natural History has been recovered from Geocoris collected at Buttonwillow and Weed, California.

A new subgenus and two new Nearctic species, Derostenus (Nearctostenus) freemani n. sp. and D. (Nearctostenus) albipes n. sp. belonging to the genus Derostenus Westwood (nee auctt. amer.), are described with host records and distribution.

Lophyroplectus luteator (Thunb.), a European ichneumonid, has been established as a parasite of Neodiprion sertifer (Geoff.) from a release made in 1962, and has dispersed approximately 12 miles (19.3 km) in the 7 years following introduction. A second, smaller release in the same year failed. In a third release, made in 1964, recoveries were made every year until sampling was stopped in 1971, but dispersal has only been approximately 2 miles (3.2 km).

The juvenile hormone was necessary for the sex accessory glands in newly metamorphosed, adult males, to produce a normal amount of spermatophore material. Protein production could be restored to normal in allatectomized newly metamorphosed roaches by implanting adult or nymphal roach corpora allata. In decapitated roaches, the weight of the accessory gland is reduced drastically. The weight of the gland could be increased by implanting adult roach corpora allata, or by injecting juvenile hormone.

Stator vachelliae new species is described from Texas, Mexico, El Salvador, and Venezuela and S. mexicanus new species is described from San Luis Potosi, Mexico. Stator usticolor (Sharp) and S. semicolon (Sharp) NEW COMBINATIONS have been determined as belonging to the sordidus complex. The following rearing records are recorded: S. vachelliae and S. subaeneus (Schaeffer) from Acacia farnesiana and S. mexicanus from Acacia cornigera.

Little attention has been given to the selection of the most effective agents for the biological control of weeds. The consequence has been a needlessly high failure rate and cost. Seven methods for their selection are discussed and a scoring system proposed as a means of incorporating their best features.

Laboratory tests were conducted to determine the susceptibility of the various larval stages of Euxoa messoria (Harris) in Ontario to four commercial preparations of Bacillus thuringiensis Berliner: Thuricide® 90TS, Thuricide®-HP, Biotrol® BTB 183, and Dipel. A field test was made to determine whether these preparations could be as effective as Dursban® (O,O-diethyl O-3,5,6-trichloro-2-pyridyl phosphorothioate) for control of this species when applied on the rye cover crop in spring.

In laboratory tests first to third instar larvae that fed on rye leaves treated with all four B. thuringiensis preparations, were found to be susceptible regardless of the rates applied. Mortality of fourth to seventh instar larvae fed treated tobacco leaves was low. Thuricide 90TS and Biotrol BTB 183 as applied in the field for control of E. messoria populations were relatively ineffective as compared with Dursban.

A method which uses the number of large embryos per adult to predict increases or decreases of green peach aphids, Myzus persicae (Sulzer), on potatoes over 3–4 or 7–8 days is presented. The population change between two successive counts 1 and 2, expressed as an increase factor (count 2 divided by count 1), is related to the average number of embryos per adult, at the time of count 1, by a linear regression (significant, P < 0.001). If there are more than about three embryos per adult, the population increases. Parasitism by Aphidius nigripes Ashm. reduces the number of embryos per adult in the field. In the laboratory, with no parasitism, the number of embryos per adult declines with age and is directly related to the daily birth rate which also declines with age.