Six trials with an unpurified suspension of Heliothis armigera nuclear polyhedrosis virus (NPV) against Heliothis armigera (Hb.) larvae on sorghum (five trials) and on cotton (one trial) during 1971–73 are described. Commercial preparations of H. zea NPV and of Bacillus thuringiensis were included in two of the trials. H. armigera NPV was as successful as a standard insecticide in preventing losses of sorghum in one trial. Lowering the rate of NPV reduced the control of H. armigera larvae. There was no difference in control achieved by spraying in the morning or in the evening. Spraying every second or every third row (relying on natural spread of the virus) reduced control. Low concentrations of molasses (0·6%) made control by 100 larval equivalents (L.E.) per hectare as good as that by 200 L.E. per hectare without molasses. Neither the commercial H. zea NPV nor the Bacillus preparation was as effective as the local virus. The local virus was reasonably effective against H. armigera on cotton at very high rates and with molasses. It was not as damaging as carbaryl to populations of egg parasites and predators, but the predators did not control damaging populations of aphid and Jassid on the virus-sprayed plots.

In Trichospilus (pupal parasites of Lepidoptera) the species are keyed out, T. ferrierei sp.n. is described from Uganda, T. vorax sp.n. from Ivory Coast (also Angola and the Kenya-Ugandan border) and T. boops sp.n. from Kenya. The known data on the South Asiatic T. pupivora Ferrière and T. diatraeae Kurian & Margabandhu are reviewed. Similarly the Cotterellia species (parasites of Hispine and Lepidopterous leaf-miners) are keyed out, and C. nitifrons sp.n. from West Malaysia and C. javana sp.n. from Java are described. The other species of the genus are annotated, including the African C. lamellata (Kerrich) comb.n. (from Chrysocharis) and C. podagrica Waterston, the Madagascan and East African C. pilosa (Risbec) comb.n. (from Eurycranium, Pteromalidae), the Ceylonese C. lankensis Kerrich and the mainly New Guinean C. insularis Kerrich.

The eggs of Aeneolamia varia saccharina (Dist.) were separated from samples of cane-field soils by means of a rotary sieve, hydrogen peroxide treatment and flotation; this method gave 76% extraction. Absolute population estimates of eggs were obtained from samples of soil (one-eighth of a cane stool) scraped from between the stems of 10 or 25 sugar-cane stools per field, the 25 pooled to give five sample groups. Relative population estimates, which took less time, were obtained from 20-g scoops of soil from between the stems of 25 stools, giving one composite sample. Taylor's power law was used to show that eggs were strongly aggregated in the dry season but less so in the wet season. The numbers of samples or sample groups needed for given levels of error were calculated from the indices of aggregation. Absolute and relative estimates of egg density were generally well correlated. The quicker relative method, suitably replicated and standardised, was considered suitable for extensive and intensive sampling.

A new approach to the study of multiple insemination in mosquitoes or other organisms involving the use of electrophoretic enzyme variants is described. Data obtained on Culex pipiens L. with this technique confirm the basic monogamy of the species and suggest that multiple insemination may occur almost exclusively within 48 h after the first mating. Two independent mechanisms are probably acting in preventing multiple insemination. The first, probably the formation of a mucoid mating plug during the first copulation, allows the fertilisation of a further 10% of eggs by the second male in double inseminations; the second, the accessory gland pheromone (matrone), after an initial latent period, totally prevents a second insemination for the duration of the mosquito's life.

Faecal pellet production by Tetranychus cinnabarinus (Boisd.) was recorded at different temperatures (19, 24, 30, 35°C) and relative humidities (0% to 100%); at all temperatures pellet production was greater under dry than under wet conditions. A feeding index based on faecal pellet production and the proportion of adults surviving each day showed that the optimal conditions for the mite were 24°C and 38% r.h. Pellet production increased under continuous light and, under any particular set of conditions, was closely correlated with the numbers of eggs laid. It is concluded that faecal pellet production can be used as a measure of feeding within a given set of conditions provided it is supplemented and checked by other data.

The north-western European species of the merula, lacteus, vipio, ultor, ater, butalidis, popularis, carbonarius and validus-groups of Apanteles are revised. Fifty species are dealt with, of which ten are described as new. Two species are synonymised, crantor Nixon with contortus Tobias, and sarcitorius Telenga with carpatus (Say). For taxonomic reasons, the geographical region under consideration has been widened to include three species from Crete (urgo Nixon, contortus Tobias, myeloenta Wilkinson) and two from Kazakhstan (lectus Tobias, electilis Tobias).

Sturmiopsis parasitica (Curr.), an important larval pupal parasite of graminaceous borers in Africa south of the Sahara, was collected from Sesamia spp. and Eldana saccharina Wlk. in Ghana. Puparia were shipped to the CIBC station at Bangalore, where a rearing technique, using field-collected borers as hosts, was devised. At 26°C the larval period was 12–14 days, prepupal period 12 h, and the pupal period 12–19 days. In its 3–4 week life span a male could successfully inseminate 4–5 females, which each produced 500–900 maggots after a gestation period of 18–19 days. In the laboratory Sturmiopsis parasitica successfully parasitised Chilo auricilius Dudgn., C. partellus (Swinh.), C. infuscatellus Sn., C. sacchariphagus indicus (Kapur) and Sesamia inferens (Wlk.); it did not parasitise Tryporyza nivella (F.) or Corcyra cephalonica (Stnt.) and was only once recovered from Galleria mellonella (L.). Its potential as a biocontrol agent against graminaceous borers in the tropics is considered high.

Night-time observations on adults of Heliothis armigera (Hb.), and data from light-trap and hand net catches in irrigated and dryland crops, showed that both sexes flew and fed and females oviposited between 20.00 and 23.00 h. From then until 02.00 h both sexes were inactive, but. from 02.00 to 04.00 h the males flew above the crop in a ‘purposeful’ manner, while the females were stationary and releasing pheromone. During this period of high male and low female activity, copulation in cages, assembly of males to females in cages and copulating pairs on crop plants were all observed. Inseminated female H. armigera were collected in crops which were at a stage suitable for oviposition, while traps away from crops or near mature crops collected mainly virgin females. It is suggested that susceptible crops attract H. armigera adults and that, once within the crop, inseminated females are ‘trapped’ by suitable physiological cues from the plants. Identification of such cues could assist in the breeding of crop varieties resistant to H. armigera attack.