The type, number, and distribution of the antennal sense organs of female Culex territans Walker and Culex restuans (Theo.) were determined and compared to similar data on Culex pipiens L., Culex fatigans Wiedemann, and Culex tarsalis Coquillett. All types of sense organs have similar distribution patterns on the five species, but large differences in number occur. These differences are discussed with regard to the host preference of the mosquitoes.

An outbreak of a sawfly, Pamphilius phyllisae Middlekauff, was discovered on northern red oak at Linn Run State Park, Pennsylvania, in 1964. The outbreak was unusual and probably unique because this previously unknown species suddenly attained populations of over 1 million ultimate instar larvae per acre. The reasons for the outbreak are not known but it arose near the end of a period of abnormally low precipitation and at a time when nearly complete encapsulation of parasites by the sawfly larvae was observed. The insect is confined to northern red oak, Quercus rubra L., and has a life cycle of 1, 2, or more years of which about 6 weeks are spent on the host tree. The life history, the history of the infestation, and the immature stages are described.

Newly emerged adults of several species of parasites of the balsam gall midge were collected in the spring and fall. Biological notes on individual species are given.

Methods of sampling to measure factors affecting fluctuations of a population of the Oriental fruit moth, Grapholitha molesta (Busck), on the Niagara Peninsula of Ontario were investigated from 1963 to 1967 in peach orchards in which no insecticides were used during the study. In most years females tended to be distributed evenly throughout the orchard and even at low fruit moth densities the trees were relatively evenly infested. Several sampling methods gave estimates of the numbers of larvae overwintering in the orchard only within wide limits but indicated that the numbers were probably small in all years. Eggs could be sampled but it was not practicable at the low densities of the moth in this study. No satisfactory method of sampling summer cocoons or adults was found. Destructive sampling of the larvae, in which they were removed from the trees and reared to maturity on green apples, gave the most precise estimates of numbers in each generation. The method also gave a measure of mortality, parasitism, and times and duration of each generation.

Extensive collections of synanthropic fly parasitoids in animal excrement accumulations in the United States, Mexico, Costa Rica, Puerto Rico, Uruguay, Chile, Denmark, Israel, and South Africa yielded seven forms of a Muscidifurax complex which were totally or partially reproductively isolated. Morphological studies of female and male parasitoids coupled with biological and zoogeographical information permitted the identification of five sibling species. Muscidifurax raptor Girault and Sanders 1910 is redescribed and four additional species are described as new: M. zaraptor, from the southwestern United States; M. raptoroides from Central America and Mexico; M. uniraptor from Puerto Rico, and M. raptorellus from Uruguay and Chile. Biological notes are added to the descriptions, and it was postulated that the genus is undergoing a process of speciation with local populations slowly becoming reproductively isolated and eventually giving rise to morphologically distinguishable entities. Most evidence suggests the establishment of Muscidifurax in the New World, concomitant with or shortly following the establishment of muscoid flies in accumulated excrement. Scanning electronmicroscopy was used in the analysis of some morphological structures.

Field populations of the European red mite, Panonychus ulmi (Koch), in Nova Scotia were separated into eggs, larvae, protonymphs, deutonymphs, and adults and the length of time each stage was present for each generation was determined in 1967 and 1968. The duration of each generation was similar in both years, although the diapause eggs hatched later in 1967 than in the succeeding year. Detailed information on the seasonal history is necessary in assessing red mite mortality and in timing of chemical controls of this pest.

Methods were developed to standardize sampling of the Douglas-fir tussock moth. Population density was estimated in terms of the number of eggs or larvae per 1,000 sq. in. of branch area of Abies concolor (Gord. and Glend.) Lindl. The density of eggs and larvae varied significantly in different parts of the tree crown. In an outbreak, egg masses were concentrated on inside branches near the bottom of the crown, but in light populations they were most common on outside branches in the top of the crown. Larvae were found over the entire tree, but they were especially concentrated on foliage in the top. Mean density of larvae in the middle crown was representative of the whole tree. Egg density is estimated from whole branches sampled representatively from three crown levels; however, density of larvae is estimated accurately from 17-in. twig samples taken from just the middle crown. Because eggs are clumped in masses and larvae are dispersed over the foliage, larval density can be estimated with much less sampling than can egg density for the same precision.

Evylaeus nigripes (Lep.) is a large, polylectic social halictine bee, common in the Mediterranean region. Haplometrotic and pleometrotic nests are established late in spring and clusters of from 6 to 15 cells are constructed and surrounded by a cavity. A summer brood of small females and a few males emerges from these cells in July. The summer females behave as workers; they remain in their mother’s nest, assist in the construction of a deeper and larger cell cluster, forage for pollen and nectar, but do not guard the nest. They show some ovarian inhibition in a matrifilial society but become egglayers in queenless nests or when establishing their own burrows. They are much shorter-lived than their mothers, require no diapause, and are unattractive to the summer males. The social level of E. nigripes is comparatively high; summer males are less than 5% of the total brood. Queen and workers are relatively distinct morphs, although caste determination can be influenced by environmental factors. Sphecodes alternatus Smith is its specific parasitoid whereas several bombyliids, mutillids, and conopids attack E. nigripes as part of a much wider range of hosts.

Blissus canadensis sp. nov. is described from Saskatchewan, Alberta, and Montana. It has reached high numbers on barley in Alberta and is a potential pest. It closely resembles Blissus occiduus Barber, and reports of B. occiduus in Canada most likely refer to B. canadensis.

Eight species of insects parasitic on the Oriental fruit moth, Grapholitha molesta (Busck), were reared from host larvae collected in a peach orchard that was unsprayed since 1962. Macrocentrus ancylivorus Rohwer was the dominant species and parasitized between 40 and 50% of first and second generation larvae from 1964 to 1966. Despite this the parasite did not appear to be a controlling factor in these years and population fluctuations of the fruit moth resulted from other causes. In 1967 parasitism rose sharply to 61% in the first generation and 74% in the second. Low adult emergence in the second generation was related directly to the increased parasitism. Effectiveness of the parasite depended both on its numbers and degree of synchronization with the development of the moth population. To determine its total effect parasitism must be measured throughout each generation of the fruit moth, because in most years it tended to reach a maximum early in the generation and then gradually decline.

An infestation of Neodiprion virginianus complex and its abrupt termination in a stand of jack pine, Pinus banksiana Lamb., in northeastern New Brunswick is described. The life history, habits, and parasites of the sawfly are reported.

Agathis pumila (Ratzeburg) and Chrysocharis laricinellae (Ratzeburg) compete for their common host, the larch casebearer (Coleophora laricella (Hübner)). An analysis of the mechanism of this competition, based on a 2-year study at Joliette, Que., is presented. A. pumila, in sacrificing part of its own population, prevents a "one stage condition" and helps C. laricinellae build up to a point where the latter becomes host-regulative by massive attack. Competitive displacement of A. pumila by C. laricinellae is less frequent than expected because of the basically different ways in which the two parasite species spread, search for, select, and attack hosts. A. pumila may suffer about 50% loss from multiple parasitism, but apparently this does not affect its survival potential, its reproductive rate, and its ability to provide significant partial control of the larch casebearer.

Heliothis stombleri, recently described as a new species from California, is shown to be an aberration of the corn earworm, Helicoverpa zea (Boddie). The aborted condition of the genitalia in the form is probably under genetic control.

The number of Medetera aldrichii Wheeler adults emerging daily in 1966 and 1967 was low and irregular. Peak numbers apparently emerged 20–30 days prior to mass emergence of Dendroctonus ponderosae Hopkins although the numbers fluctuated through the mass emergence period of the beetle. Densities of emerging adults averaged less than 1 per square foot of bark and never exceeded 6.0 per square foot. Densities of the emerging flies and beetles did not appear related.Adults mated on the bark surface of trees infested with D. ponderosae; mating habits are described.Females oviposited in degenerate resin ducts in the bark surface. Two eggs per duct were the modal number. Seven or more per duct were found in less than 5% of the ducts examined.

Lipoptena pudui n. sp. was taken from the cervid Pudu pudu (Molina), in central Chile. This is the first ked-fly known from this species of pygmy South American deer. The new species is closely related to L. guimaraesi Beq. and is characterized chiefly by the long narrow palpi and the non-constricted pronotum. A revised key to the New World species of Lipoptena is presented.

Ips integer (Eichhoff) is removed from synonymy with plastographus (Leconte), which in turn is divided into two subspecies: p. plastographus (Leconte) and p. maritimus n. subsp. The former occurs in the subalpine zone of the Sierra Nevada, Cascade, and northern Rocky Mountain ranges; the latter is apparently restricted to the California coast.I. integer and p. plastographus are partially sympatric, but even in a mixed attack on the same host the two species were rarely found in the same gallery systems. In field experiments females showed strong preference for the sex pheromone of conspecific males. Laboratory-produced hybrid males were intermediately attractive to both species.In breeding experiments the plastographus subspecies were fully interfertile but fertility of backcross and F2 generations was reduced. Egg hatchability was low in interspecific combinations of integer and plastographus. However, results were different for the reciprocal pairings and the backcrosses showed increased fertility. These data defy explanation by nuclear genetics but may result from cytoplasmic incompatibility.Although integer and the two plastographus subspecies have the same karyotypic formula, 15 A A + Xyp, the three entities can be differentiated by the size of heteropycnotic segments in pachytene chromosomes and the shapes (centromere position) of some of the five largest chromosomes at second metaphase. Univalents, multivalents, bridged anaphases, and other abnormalities were common in hybrids of plastographus and integer. Heteromorphic bivalents, but no other abnormalities, were observed in hybrids of the plastographus subspecies.

After diapause was initiated in reproductively active adults, short-day (LD 12:12) maintained diapause and prevented oviposition for 66 ± 22 days. Subsequently all females remaining in the conditions that produced diapause (LD 12:12), began to lose the red-brown diapause coloration and began to oviposit. When animals were transferred to long-day at various intervals during diapause, oviposition resumed within similar time periods, thereby indicating that the intensity of diapause did not differ at the times tested.We suggest that in nature the short days of early autumn induce diapause, that the short days of late autumn maintain this diapause, that subsequently diapause ends under short-day conditions and that factors other than photoperiod, such as temperature accumulations, play a primary role in timing the initiation of reproduction in late spring.

Residue analysis of forest soils sprayed once at 1 lb/acre showed little breakdown of DDT through 9 years after application. In the absence of appreciable downward trend, residue persistence could not be estimated beyond stating that it appears to persist much longer than the 10 years suggested by others. Persistent residues are largely restricted to the upper soil litter. Residues pass from soils to earthworms to robins throughout the 9-year period studied. It is suggested that this relationship may persist for as long as 30 years after a single application to the forest. Biological magnification of residues in robins is demonstrated. Significance of these residue levels is discussed.

Larvae of the eastern hemlock looper, Lambdina fiscellaria fiscellaria (Guen.), are susceptible to a nuclear polyhedrosis virus as well as nuclear polyhedrosis viruses isolated from the western hemlock looper, L. f. lugubrosa (Hulst), and the western oak looper, L. f. somniaria (Hulst). The pathogenicity of these viruses was similar when tested on eastern hemlock looper larvae and it is suggested that the same virus infects the three subspecies. Resistance to the virus did not increase with age; second-, third-, and fourth-instar larvae were equally susceptible. The period from ingestion to death varied with concentration of virus and rearing temperature. Results of pathogenicity tests are given.