The physical association between Dendroctonus ponderosae Hopk. and its associated blue stain fungi Ceratocystis montia Rumb. and Europhium clavigerum Robinson and Davidson and the yeasts Pichia pini (Holst) Phaff, Hansenula capsulata Wickerham, and H. holstii Wickerham is described in single broods reared in bolts of lodgepole pine, Pinus contorta Dougl. var. latifolia Engelm. Eggs just prior to hatch and first-instar larvae were always in contact with the microorganisms whereas newly laid eggs, second-, third-, and fourth-instar larvae were not. During pupation, blue stain fungi and yeasts colonized pupal chamber walls. Transfer of these microorganisms to the new generation of insects was ensured when tenerals contacted the microorganisms lining the pupal chamber. Ensured physical contact between these organisms supports the hypothesis of a symbiosis between them.

The egg and five nymphal instars of Podisus placidus Uhler and Stiretrus fimbriatus (Say) are described and illustrated. The nymphal instars can be separated on the basis of head width or pronotal width. No overlap was encountered in the nymphal instars studied.P. placidus overwinters as an adult. Egg development in the laboratory took approximately 6.0 days. The average time spent in each of the five nymphal stages was 5.4, 4.6, 4.9, 4.7, and 7.6 days, respectively. Development of S. fimbriatus eggs took approximately 9.5 days. The average time spent in each of the five nymphal instars was 5.1, 4.3, 4.1, 4.3, and 8.2 days, respectively. Adults of S. fimbriatus were parasitized by Cylindromyia fumipennis (Bigot) (Tachinidae).

Overwintering eggs of the fruittree leafroller, Archips argyrospilus (Walker), began to hatch 13 April 1970, and larval emergence was completed by 8 May. Individual egg masses hatched in an average of 4.3 days, but the total time for larval emergence in all egg masses spanned a 25-day period. No egg parasites were observed. Winter mortality of egg masses was only 2%.A pink bud spray of diazinon gave good control of the fruittree leafroller and did not affect biological control of spider mites. Chlorphenamidine showed promise, but trees sprayed with this material developed a high population of the McDaniel spider mite, Tetranychus mcdanieli McGregor, during the summer. Phosalone and tetrachlorvinphos reduced the incidence of fruittree leafroller damage below that of the nonsprayed check but did not provide satisfactory control.

A striking new species, Agriotypus himalensis, is described from Assam (India) at 7200 ft in the Himalayas. The family Agriotypidae is maintained as distinct because of the structure of the adult abdomen and larval head.

The objects of this study were to determine whether the population density of Hyphantria cunea Drury is dependent on land use, vegetation pattern, and plant species; and to compare the extensive methods designed for this work with more intensive, single-plot designs.In two separate gradations, covering a period of 12 years, density was positively correlated with agricultural land use, open rather than closed patterns of vegetation, and the occurrence of only a few of the principal host species. The analysis showed how these variables affected density both within and between different climatic areas, and suggested how cultural methods might be used in population management.Extensive designs permit the development and testing of holistic models designed to explain both spatial and temporal differences in population density, and provide the replication required for the latter purpose. It is important to model spatial differences in density because such variables as vegetation pattern and composition are sometimes subject to cultural modification. Very intensive designs, based on sampling only a few trees at one point, do not permit the development of complete models and, because of plant host and dispersal phenomena affecting insects and their parasites, produce data that may be unreliable even for sub-models, such as those dealing with host–parasite interactions.

Females of Muscidifurax zaraptor K. & L. oviposit on unparasitized housefly (Musca domestica L.) pupae in preference to those attacked by M. zaraptor, Nasonia vitripennis (Walk.), or Spalangia cameroni Perk. (Hymenoptera: Pteromalidae). The discrimination against parasitized houseflies is greatest in the case of those attacked by M. zaraptor and least for those parasitized by S. cameroni. Discrimination is based on differences between unparasitized and parasitized pupae that the female parasites detect after they pierce the pupae with the ovipositor. Death of parasitized hosts, or a change resulting directly therefrom, is not responsible for the differences. The fact that hosts pierced at or near the original drilling site are more likely to be rejected than those attacked elsewhere supports the hypothesis that a ’venom’ injected by the female parasites during oviposition diffuses throughout the host and is responsible for oviposition restraint.

Two new species of Naphius Stål are described, and a key to the known species is given.

A Berlese–Tullgren funnel is described which features a 600-w heating element, a tray having a single bottom of new design, and ventilating screens below the tray to prevent condensation of moisture on the inner wall of the funnel. The funnel efficiently extracts grassland arthropods from coarse plant matter. Also described is a salt-water flotation separator, which extracts any arthropods from the fine litter and soil that may pass through the funnel screens.

The trombidiid subfamily Neotrombidiinae Feider is re-established and redefined, based primarily on larval characters but also on adult characters. It is closely related to the trombidiid Trombellinae on the one hand and to the Leeuwenhoekidae on the other. It consists of two genera, namely Monunguis Wharton, which is monobasic and known only from the larva, and Neotrombidium Leonardi, with 13 described species of which 7 are known from the larva and 8 from the adult (the larva and adult of 2 species are correlated by rearings).The history of the family-level placement of this group, and the controversy over whether or not to recognize two genera, are reviewed. The characters that justify the separate recognition of Monunguis and Neotrombidium are enumerated.The larva of each of the following species of Neotrombidiinae is described, illustrated and keyed: Monunguis streblida Wharton from the Caribbean area, Neotrombidium barringunense Hirst from Australia, N. tricuspidum Borland from North America, N. tenuipes (Womersley) from Malaya, N. samsinaki (Daniel) new combination from central Europe, N. anuroporum new species from Central America, N. bengalense new species from India, and N. tenebrione new species from eastern North America. Six other species of this group, known only from the adult, are listed separately but are not treated taxonomically here.The larvae of Neotrombidiinae parasitize adult insects: those of Monunguis are hyperparasites on streblid flies whereas those of Neotrombidium are ectoparasites of cerambycid, clerid, elaterid, and tenebrionid beetles that pass part of their life history under the bark of trees.In the Microtrombidiinae, Camerotrombidium Thor is noted as the valid replacement name for the preoccupied Ottonia Kramer.

A new species, Einfeldia synchrona, is described and compared with a closely related species, Einfeldia pagana (Meigen).

Einfeldia synchrona Oliver is univoltine in a small, shallow, highly eutrophic pond near Ottawa (45°N.). Adult emergence is synchronized with slight protandry in May, and from this small pond exceeded 145,000 individuals in 1970. Emergence is inhibited experimentally at short photoperiods. More than one egg mass is produced, during a period of several days following emergence. First instar larvae, which lack ventral tubules, are at first pelagic but build cases before moulting. The remaining three larval instars possess 1 pair of ventral tubules. Larvae show a preference for central areas of the pond over 40 cm deep, and show some mobility in response to seasonal depth changes. There are arrests in the development of larvae both in winter and during summer, with cessation of feeding, penetration into the mud, and construction in winter of special sealed cocoons. Marked year to year differences in the stage reached by winter, and in the larval population level, were detected. Many of these biological features are probably widespread in Chironomini and hence of some importance in the interpretation of studies of the bottom fauna.

Evidence is given in support of the hypothesis that the spatial arrangement of attacks by the mountain pine beetle (Dendroctonus ponderosae Hopk.) on its host, lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.), is largely determined by the pattern of bark niches suitable for attack initiation. Density of attack sites and bark thickness are important in determining the attack-harbouring potential of the bark and in determining the upper limit of attacks, thus, the potential area available for attack on the bark surface of lodgepole pine trees. At fixed levels on the clear bole of naturally infested trees, attack pattern tends to be regular owing to the regular spatial pattern of suitable attack sites. The regularity of the attack pattern is disturbed by the presence of an attack-density gradient around the stem circumference. The vertical attack-density gradient over the host is well described in terms of a relation between attack density and bark thickness. This relation is asymptotic and rests on the assumption that the density of bark niches suitable for attack initiation approaches an upper limit with increasing bark thickness on lodgepole pine trees.

Notes are given on type material of 25 nominal species either referable to the genus Sphaerophoria or described in that genus and referable to the genus Ischiodon. Lectotypes are designated for 15 of these species. New synonymy is indicated for 13 nominal species on the basis of examination of type material and for three other nominal species on the basis of published figures of male terminalia of type material. One species frequently referred to the genus Sphaerophoria is transferred to the genus Allograpta.