Between January 1965 and August 1967 49 species of biting flies were caught in Langridge and Fredeen traps and from bait animals in western Uganda. Catches were recorded daily, and monthly catches (geometricmeans) of the species most frequent on bullocks were plotted as percentages of the year's catch. Haematobia minuta (Bez.) was the only species to show a unimodal peak; this is attributed to maintenance of soil conditions suitable for the larvae during the short rains (September-November). Bimodal peaks are shown by Haematopota brunnescens Ric, H. patellicorne (End.),Tabanus par Wlk., Stomoxys inornata Grünb., S. nigra nigra Macq. and Haematobosca squalida (Grünb.) (adversely affected by severe dry conditions), by T. taeniola P. de B. and T. thoracinus P. de B. (emergence from pupae coincides with the beginning of the rainy seasons (March-May and September-November)), by Stomoxys omega Newst. and Haematobiaspinigera Mall, (minimum numbers in the wet months September-October), and by species of Haematopota, Tabanus, Chrysops, Stomoxys and Haematobosca(breeding occurs in the rainy seasons). Ill defined cycles are shown by Chrysops distinctipennis Aust, C. longicornis Macq., S.ochrosoma Speiser and females of S. calcitrans (L.) ; Glossina fuscipesNewst., G. fuscipleuris Aust. and G. pallidipes Aust. showed minimum numbers in September-October.

Following examination of Cicadelloidea off potato, castor, millets and berseem from Simla, India, and of some of Distant's type specimens, the genera Jilinga, Pseudosubhimalus and Sarejuia are described as new, and new combinations and synonymies given ; two new species are also described under Aconurella Ribaut and Sarejuia. Dio Distant, Erythridea Ribaut and Erythria Fieber are considered to be distinct, and a key to these genera is given.

The emission and form of the spermatophores of Eriophyes sheldoni Ewing are described and illustrated. Glued to the substratum by a drop-like pad which varies in shape, they consist of a stalk with a basal stiff section and a distal flexible part ending in a strongly convex lens-like head, in which the sperm mass is kept. The fine structures of the adult integument, characteristic of this species, are described and illustrated.

Two field strains of Lucilia cuprina (Wied.) of different susceptibilities to diazinon were selected over 25 generations by immersion of first-instar larvae in aqueous emulsions of diazinon for five minutes ; the resistance of the larvae and adult females was compared with a standard laboratory susceptible strain. Resistance increased rapidly in both strains, reaching a maximum for adult females (R.F. = 5–6) in generation 3 and for larvae (R.F. = 46–60) in generation 6. After removal of selection pressure at generation 8 the resistance factor fell to 20–24 by generation 25. Because the resistance mechanisms are known to place their carriers at a disadvantage in the absence of selection pressure, the practical implications of the rapid increase in resistance must await results of experiments with known genotypes.

The long range orientation of West African mosquitoes to birds was studied using ramp-traps set up 3–23 m from the bait. The baits comprised chickens, ducks, pigeons and the carbon dioxide equivalent of the chickens. From the pattern of convergence of mosquitoes to the baits, it was shown that Anopheles melas Theo. and Culex thalassius Theo. were orienting to all the bird-baits from distances of at least seven metres. Responses to carbon dioxide were only apparent at a distance of three metres indicating the greater range of effect of the chickens over their carbon dioxide equivalent. Mosquitoes of the largely bird-biting C. decens group showed no long range response to any bait, even though they were entering pigeon-baited traps and to a limited extent feeding on the birds. Catches of A. melas in bird-baited traps were larger at the foot of a tall tree than in the foliage at 5·33 m; for Culex spp. the converse was true. Catches of Culex at 5·33 m outside the tree were smaller than within the foliage.

Operated in sheltered woodland, the samples obtained by Rothamsted tungsten-filament and Robinson mercury-vapour traps are best described by a spatial model different from that used in a site exposed to wind. Differences between the proportions of Noctuidae and Geometridae were accountable to differences in height of flight. The Rothamsted traps gave more consistent samples than the Robinson traps and averaged about onequarter the number of moths.

Life-cycle variation, involving alternative methods of overwintering (holocycly and anholocycly), is found in many important pest aphids, and may have considerable ecological, genetic and economic significance. The occurrence of life-cycle variation in Myzus persicae (Sulz.) in different parts of the world is reviewed. The holocycle of M. persicae, with sexual reproduction and overwintering of eggs on Prunus, occurs in the temperate regions of every continent, and although anholocycly is widespread in warm climates there are indications that the potential for sexual reproduction may be retained throughout the whole range of the species. The environmental factors involved in the determination of sexual morphs are considered. Photoperiodism provides the timing mechanism for sexual morph production, and the photoperiodic response is probably tuned to different regional conditions and buffered against other environmental variables within certain limits. The only other environmental factor clearly implicated in sexual morph production is temperature, and an attempt is made to correlate the global pattern of life-cycle variation in M. persicae with temperature differences between regions, by dividing the world into six zones delimited by selected isotherms. The overall pattern of life-cycle variation can be explained largely on the basis of climatic differences between zones, and the effects of these differences on gene and genotype frequencies within the species. Clones of androcyclic character seem to be widespread and, although genetically isolated anholocyclic biotypes undoubtedly exist, androcyclic clones could be the principal source of parthenogenetic overwinterers in all parts of the world where life-cycle differences exist within populations.

Two toxic baits, one containing aldrin and the other containing mirex, were compared for their effectiveness in killing field colonies of Atta cephalotes (L.) and Acromyrmex octospinosus (Reich) in Trinidad, West Indies. The fate of these two toxicants within tie nests was followed by using radiolabelled bait. Of the two baits, mirex appeared to be more acceptable to both species of ant. With Acromyrmex, the ratio of living to dead fungus gardens was not affected by the bait used, whereas with Atta there was a significant difference, aldrin killing many more gardens than mirex. For both species the proportion of medium-sized workers radiolabelled was significantly greater than for the other castes, and mirex marked greater numbers of all castes than did aldrin. Greatly different proportions of Atta workers were radiolabelled in the different fungus gardens of a nest with both baits. More radioactivity was detected in the fungus gardens treated with mirex, the difference being significant for Atta but not for Acromyrmex. Mirex bait particles incorporated into the fungus gardens were significantly smaller than aldrin bait particles, indicating different degrees of comminution by the ants.

The management of the sugar-cane crop in Trinidad involves widespread aerial spraying against the sugar-cane froghopper (Aeneolamia varia saccharina (Dist.)). For control decisions to be made on an economic basis, information concerning the damage and control relationships associated with this pest is required. Assuming a linear damage function, a cost-effective analysis based on the relative cost of eliminating adult-days is made concerning the choice of insecticide and the decision—when to spray. It appears that a first-brood spraying strategy is more cost-effective than a strategy of later-brood spraying alone, provided that the density and duration of the first-brood can be accurately monitored.

Achrysocharis diplosidis reared from galls of the Cecidomyiid Hyperdiplosis eupatorii Felt in Trinidad and Brazil is described, A. pulcherrima Kerrich is recorded from Pakistan, and a key separating these two gall-associated species of Achrysocharis Girault is given. Larval or pupal parasites of Promecotheca cumingii Baly (Hispidae) in Sri Lanka are described as Cotterellia lankensis, and of Promecotheca spp. in New Britain, Admiralty Is. and New Guinea Territory as C. insularis; C. podagrica Waterston is redescribed, and a key is given to the three species of Cotterellia Waterston ; the generic relatives of Cotterellia are discussed and a key separating this genus from Platocharis Kerrich and Schizocharis Kerrich is given. Rekabia Cameron is placed in synonymy with Euplectrus Westwood, and notes are given on material for a classification of the relatives of Stenomesius Westwood.

The egg, five larval instars and pupa of Milionia isodoxa Prout are described, and the adult is redescribed. Setal maps for the first and fifth larval instars are presented.

Milionia isodoxa Prout is a serious defoliator of planted hoop pine, Araucaria cunninghamii, in the Highlands of Papua New Guinea. The insect has been found in seven mainland districts, and larvae have been collected from naturally occurring hoop pine in the Madang and Southern Highlands Districts. M. isodoxa is multivoltine, the life-cycle taking approximately eight weeks. The durations of the five larval instars are 4, 4, 4, 5 and 10 days, respectively, and of the pupal period approximately two weeks. The males feed primarily on organic solutes, the females on nectar, so that the sex ratio of adult M. isodoxa in the hoop pine plantations at Bulolo varies with the time of day and locality. Pupae may be attacked by two species of Ichneumonidae and one of Braconidae, and the ants Anoplolepis longipes (Jerd.) and Oecophylla smaragdina (F.) are particularly effective larval predators in the Bulolo plantations; some adults are killed by spiders. The fungus Beauveria bassiana is responsible for high pupal mortality in the Highlands. Frass-drop frequency studies of M. isodoxa larvae in the laboratory showed that feeding activity is greatest in the early instars, and is greater at night for all instars. Larvae reared at 21°C required 14 days more for development than did those reared under the normal daily fluctuation, 19–31°C.

Adults of the cabbage root fly (Erioischia brassicae (Bch.)) reared in culture were inactive on the day of emergence but they fed on carbohydrate (sucrose) and protein (Yeastrel) on day 2. Without food, the egg follicles increased to approximately one-third of their maximum size and were then resorbed. When food was available, females ingested sucrose on days 2 and 3 to mature the first batch of eggs, without any stimulus from mating. Without either a mate or a suitable oviposition site, females retained most of their eggs. Females obtained sufficient food for egg maturation by day 4, when their egg follicles were 400 μm, approximately half the size of the mature eggs. Only females mating on day 4 laid eggs at the expected time 6±0·3 days after emergence. With a suitable oviposition site, these females laid 299±48 eggs, approximately twice as many as any other females, and ten times as many viable eggs. When males were not allowed to mate, peak ingestion was delayed from days 8–12 to days 14–18. Mated females provided with an oviposition site laid most eggs on days 5 and 6 and fed again on day 7. This second peak of feeding was delayed until day 9 when mated females were denied, or unmated females were given, an oviposition site. Similar volumes of sucrose were imbibed by females whether they laid or retained their eggs. Females denied both a mate and a suitable oviposition site laid less than 1% of the expected eggs.

A new species of Tropiduchidae, Biruga chariclo, is described from adults and nymphs intercepted by the U.S. Department of Agriculture on palm fronds imported from Mexico, and the genus is redefined.