The north-western European species of the vitripennis, pallipes, octonarius, triangulator, fraternus, formosus, parasitellae, metacarpalis and circumscriptus-groups of Apanteles are revised. Sixty-five species are dealt with, of which twenty-four are described as new. One species, A. exiguus (Haliday), is lifted from synonymy. Brief notes are added on North American species of the circumscriptus-group in the British Museum (Nat. Hist.) to assist their eventual correlation with the European species. Reference is also made to two species of Hypomicrogaster.

Records were kept of the catches of tsetse fly by three types of traps, the Langridge box screen, the Swynnerton awning screen, and a modification of the latter incorporating a screen skirt, in the South Busoga fly-belt, Uganda, where Glossina pallidipes Aust., G. fuscipes Newst. and G. brevipalpis Newst. are abundant. Only two specimens of G. brevipalpis, but large numbers of the other two species, were caught, by far the largest catches being obtained by the awning screen-skirt trap.

The biology of Paropta paradoxus (H.-S.), a new pest of the grapevine, was studied in field and laboratory during 1962–1972. Descriptions are given of the imago and developmental stages. The life-cycle is completed in 1–3 years. Adults are active during April–September, and eclose mostly during the day with a male/female ratio of 0.65 (3.3 in UV light-trap catches). Light induces a deep torpor in most adults. After mating, which lasts 30–60 min, females lay up to 275 eggs in their life span of 1–14 days (males 2–13 days). In the vineyard eggs are glued under loose bark, in batches of 15.6 (1–63), and hatch in 20–32 days. The neonate larvae disperse and settle under loose bark where they begin feeding; penetration of the wood is mainly through dried stubs of pruned canes, and galleries are excavated along the axes of stems and branches. Larvae may also develop under dry bark. The pest overwinters as active immature larvae and diapausing mature, prepupal larvae. The pupa is usually formed in the larval galleries, and lasts 16–45 days. In heavily infested vines the pupae may be cannibalized by larvae; both larvae and pupae may be preyed on by woodpeckers.

Responsiveness to stimuli eliciting probing was measured in individual, suspended males of Glossina morsitans Westw. The standard stimulus was a warmed foam rubber ball offered from below; a positive response was recorded if the fly exsheathed its haustellum and probed the foam. During four days without food, probing responsiveness increased linearly from zero in mature flies, but with an initial step-up in tenerals. Each day's increase was steeper than the overall rate, and apparently modulated in the V-shaped pattern typical of other responses in tsetse flies. Starvation is thus seen to induce changes in feeding thresholds which parallel those induced in flight behaviour.

A survey of alcohol dehydrogenase (Adh) in Culex tritaeniorhynchus Giles has uncovered five electrophoretic variants among laboratory strains. Detailed genetic analysis revealed that these variants are inherited as codominant alleles at a single locus. The Adh locus has been assigned to linkage group III between s and cl. A survey of a natural population from Lahore, Pakistan, revealed the presence of four of the five variants and suggests the possibility of using this enzyme polymorphism to monitor a release programme. Substrate specificity tests suggest that this enzyme can utilize almost any aliphatic primary alcohol as a substrate.

A technique is described for the preparation of large quantities (up to 1100 kg) of plain and waterproofed leaf-cutting ant bait from dried citrus meal, soyabean oil and aldrin. Small amounts (500 g) were weathered in sun and shade during wet and dry periods in Trinidad and the acceptability of the bait to ants {Acromyrmex octospinosus (Reich) and Atta cephalotes (L.)) and the persistence of toxicants in it were assessed in laboratory tests. Methyltrichlorosilane was the most effective of three waterproofing agents tested. In the wet season, waterproofed bait remained acceptable to ants for at least 30 days whereas plain bait deteriorated in less than four days; in the dry season waterproofed bait was only marginally more attractive. In the wet season, Acromyrmex strongly preferred weathered waterproofed bait to fresh leaves, whereas Atta slightly preferred leaves to bait. In the dry season, Acromyrmex showed little preference between bait and leaves, whereas Atta strongly preferred bait. Over the period that the bait remained attractive to the ants it retained between one-third and two-thirds of the original aldrin in the form of aldrin and dieldrin.

Aircraft were used to apply a bait containing aldrin, soyabean oil and citrus meal against leaf-cutting ants (Acromyrmex octospinosus (Reich) and Atta cephalotes (L.)) in Trinidad. The distribution patterns of bait applied by different aircraft were measured. Plain bait applied at 2.2 kg/ha to an uncultivated island in the dry season destroyed 91% of nests of Acromyrmex, and waterproofed bait applied in the wet season to cultivated land on the mainland destroyed 85%. Small nests of Atta were also destroyed by this treatment but large nests in forest required much heavier dosages applied to the nest itself. Lizards and crabs living in the baited areas were contaminated with aldrin but there was no evidence to show that they were harmed.

The losses caused by leaf-cutting ants (Acromyrmex octospinosus (Reich) and Atta cephalotes (L.)) to citrus and cocoa crops in Trinidad were assessed as about $40 000 TT per annum in each of these crops. Losses to other crops were unassessable on a national scale but often important to individual farmers. Aerial baiting, using a locally produced bait of aldrin, soyabean oil and citrus meal, would be at least as, and probably more, effective than current on-farm control methods. The cost was $6.18/ha, approximately four times cheaper than current methods and twice as cheap as searching for nests and applying the same bait to them by hand. Hand baiting with the local bait would be almost twice as cheap as using the imported alternative available. At the dosages and frequency of application recommended (2.2 kg of bait containing 0.4% technical aldrin/ha/annum) the total amount of organochlorine insecticide currently used against leaf-cutting ants in Trinidad would decrease between two- and ten-fold, depending on the area treated. Serious long term residual effects are most unlikely to develop, and if bait were applied carefully no harmful effects to man or stock would occur. Farms larger than four hectares would benefit proportionately more than smaller farms, unless charges were manipulated. Fewer men would be needed to control ants than at present. Losses to traders caused by a decrease in the sales of alternative insecticides would be trivial. A national dry-season baiting scheme would utilize more fully aircraft already available in Trinidad, and would help export crops and the production of home-grown foods.

Larvae of Aphidoletes Kieffer and Monobremia Kieffer feed exclusively as predators on aphids. The taxonomic status of these genera and their included species is reviewed and new generic and specific synonymies are given. A. aphidimyza (Rondani), A. urticariae (Kieffer), A. abietis (Kieffer), A. thompsoni Möhn and M. subterranea (Kieffer) are accepted as good species and a neotype is designated for A. urticariae. Diagnostic characters of these species are indicated and characters of the male genitalia, female wings and larval skins are illustrated. Published information on their biology, particularly of the commonest species A. aphidimyza, is summarized and includes details of host ranges and geographical distribution. Lestodiplosis grassator (Fyles), L. pini Barnes, Trilobia aphidisuga Del Guercio, Uncinulella eriosomiperda Del Guercio, Trilobiella siphae Del Guercio and Adelgimyza strobilobii Del Guercio probably prey on aphids but have not been recognized since they were originally described. Comparative assessments of field populations of Aphidoletes by examination of aphid colonies in the field, by incubation of samples in polythene bags and by laboratory examination of samples fixed in 70% ethyl alcohol showed that only the last gives accurate counts of eggs and larvae. Counts of aphids, Aphidoletes, Syrphids, Coccinellids and Anthocorids in 35 samples taken from aphid colonies occurring at Wisley in 1970–72 are tabulated, together with seven samples from other localities. Aphidoletes (mainly A. aphidimyza) was numerically the dominant predator in all three years at Wisley and was about ten times more numerous on wild plants than on cultivated plants.

Weekly catches of five species of mosquitoes over nearly two years at Belém, Brazil, were plotted against accumulated rainfall during the four weeks before catching. Rain-pool-breeding species (Aedes serratus (Theo.), A. scapularis (Rond.), Psorophora ferox (Humb.)) show a marked peak in catch size (population density) at 100–180 mm accumulated rainfall; one swamp-breeding species (Culex portesi Senevet & Abonnenc) shows no relation to rainfall while another (C. taeniopus D. & K.) reaches a plateau at 180 mm. A more detailed analysis of catches in relation to rainfall distribution showed that maximal populations of A. serratus appear 16 days after 39.7–87.9 mm of rainfall has accumulated over 14 consecutive days, which should include 3–7 dry days; P. ferox requires 55.2–99.4 mm rainfall in the same period; and A. scapularis requires 26.5–114.9 mm rainfall, with a marked alternation of wet and dry days.

The ability to mature eggs without feeding on blood (autogeny), occurring in most populations of Culex tarsalis Coq., approaches an incidence of 50% in the Bakersfield, California strain. Females that were not allowed to lay eggs matured autogenously would occasionally feed on blood but much less readily than anautogenous females. When such females did feed on blood, additional eggs started maturing in other follicles. This produced a heterogeneous assemblage of eggs, some matured autogenously in primary follicles interleaved with others in secondary follicles (on other ovarioles) that matured following the blood-meal. During or soon after autogenous maturation of eggs in some primary follicles, the contemporary primary follicles were resorbed, forming ovariolar dilatations, a condition commonly interpreted as signifying a parous condition.

The biology of Anopheles claviger (Mg.) was studied for a varying number of years in three localities in southern England. The fluctuations in the proportions of the larval instars and pupae were studied by weekly sampling throughout the year. The population overwintered from October to April as pre-adults, and in mid-winter larval development was arrested, but was resumed in March. The construction of a simple life-table showed the existence of a large mortality of immature stages during the overwintering period. Females were sampled at two localities by human bait catches, and at one also by insect suction traps. There was an interval of 1–2 weeks between adult emergences in April and blood-feeding, during which time females apparently fed on sugar solutions. Maximum biting densities of nullipars in May and September showed that A. claviger was bivoltine. The physiological age structure of the population showed that most parous adults at bait had oviposited only once or twice, but a few females had laid four batches. Live Hygrobatid-type mites proved reliable in indicating nulliparity. Mature larvae developed in the eggs 5–7 days after oviposition and while most eggs hatched within the next three days, a few remained unhatched until the 30th day. Females of the second generation (September) laid fewer eggs than those of the first generation (May). About six days were required for blood digestion, and females supplied with sugar were able to live 46 days. The marked delays between successive gonotrophic cycles in natural populations would make parous rates unreliable for the estimation of daily mortalities.