In an attempt to define the favoured hosts of Culex portesi Senevet & Abonnenc and C. taeniopus D. & K., one bat, ten rodents, four marsupials, two birds and one crustacean, one amphibian and one reptile were exposed in groups of six in suction traps located in a forest in Trinidad. Each group of six baits included two white mice as a standard. The numbers of mosquitoes caught at each bait on three or six replicate exposures were analysed by an analysis of variance to separate population and site variations. Baits were then compared for ‘attractiveness’ by ranking according to an adjusted mean catch for each mosquito species. The proportion of each mosquito species that engorged on individual baits was also determined. In some cases, attraction and engorgement varied widely, and this was attributed to defensive action on the part of the bait animal. It was concluded that C. taeniopus was particularly attracted by the opossum Didelphis, which was superior to all indigenous mammals, while C. portesi was attracted to a wide range of rodents and marsupials. Neither was attracted by the cold-blooded animals. Both mosquitoes engorged well on the relatively insensitive marsupials with long bare tails, Dideiphis, Marmosa and Caluromys, and also on the well-furred but diurnal squirrel. Of the mainly nocturnal remainder, Culex portesi showed higher engorgement rates than C. taeniopus, suggesting a more aggressive or persistent feeding behaviour.

A key is provided to the eight genera of Anomaloninae occurring in Melanesia. The Anomaloninae are endophagous parasites of Lepidoptera and Coleoptera larvae. The Melanesian species of Anomalon Panzer, Trichomma Wesmael,Heteropelma Wesmael, Therion Curtis, Pseudanomalon Szépligeti, and Aphanistes Foerster are keyed and discussed. A total of 21 species is recognised of which 11, Trichomma cheesmanae sp. n., T. pacificum sp. n., Heteropelma hirsutum sp. n., Therion unguiculum sp. n., A phanistes nexus sp. n., A. luscus sp. n., A. limulus sp. n., A. dnopherus sp. n., A. paupus sp. n., A. sedlaceki sp. n. and A. anaxeussp. n., are described. An Australian species, Anomalon, morleyiGauld, is recorded from Melanesia for the first time. Trichomma elegantulum Turner is placed as a junior synonym of T. clavipes Krieger.

Samples of larvae of Aedes aegypti (L.) were collected in three principal habitats, domestic, peridomestic and feral, in the Rabai area in eastern Kenya. The samples from the domestic habitat represent the population of the domestic form, A. a. aegypti, and the feral samples from tree holes from Bejumwa Forest represent the feral subspecies, A. a. formosus (Wlk.). The peridomestic samples from steps cut into trunks of coconut palms most probably represent hybrids between the domestic and the feral forms. These samples were brought to the laboratory where they reproduced in high numbers, and crosses were made between the three populations. Adults of the parental populations and those resulting from the crosses were marked with different colours of fluorescent pigments, released in the peridomestic habitat in the Rabai area and subsequently recaptured in biting catches on man in the domestic and peridomestic habitats. The results indicate that domesticity, particularly house-entering behaviour, in A. aegypti is genetically controlled and is a product of the action of several genes. The gene action in terms of house-entering behaviour is additive as can be clearly seen from the recapture data for the various crosses. The percentage entering houses was highest among mosquitoes of the form from inside houses (the domestic A. a. aegypti population (D)) and the percentages decreased progressively through the peridomestic (P) and hybrid forms to the feral population of A. a. formosus (F) in the following manner: D (45·)DP (15 ·5), PD (13·9), P (9·8), DF (5·7), FD (73·), PF (1·5), FP. (0·6) and F (0·6).The recaptures outdoors were in the reverse order, the highest percentage being for F (187·) and the lowest for D (8·5), DP (8·0) and PD (7·7). The data suggest that the larvae from the peridomestic habitat may represent hybrids between the domestic and feral forms

A model for the inheritance of behavioural characters in mosquitoes is presented. On the basis of isolating mechanisms and partial hybridisation, it is concluded that A. a. aegypti and A. a. formosus have developed as geographically isolated allopatric populations. This supports the existing polytypic concept of speciation in A. aegypti. Spatial distribution, non-random mating and the existing series of isolating mechanisms indicate that the domestic type form has been introduced into East Africa, most probably on ships.