Culicoides anophelis Edw. is of wide occurrence in India, Ceylon, Burma, Malaya, Thailand, Indo-China, Sumatra, Tonkin, and as far as New Britain (Laird, 1946). From India the species has almost invariably been obtained in the act of engorging on female mosquitos, mostly Anophelines (A. annularis Wulp, A. hyrcanus nigerrimus Giles, A. barbirostris Wulp, A. subpictus Grassi, A. vagus Dön., A. aconitus Dön. and A. maculatus Theo.). But the species may also attack members of the Culicini, as observed by Fearnside (1900) in the case of certain unidentified examples of the genus Culex. We have also observed the species attacking Culex pipiens fatigans Wied. and Mansonia (Mansonioides) annulifera (Theo.), which suggests that the occurrance of the species is not so uncommon on members of the Culicini as was thought previously. The reason for the missing of the association of the species with the latter group of mosquitos by most workers seems to lie in the fact that the Culicini were not examined previously in large numbers (Edwards, 1922).

Twenty one species of ticks (Ixodoidea), one of which is represented by two subspecies, are recorded from the Bechuanaland Protectorate. Localities, dates and the hosts are given; general distribution and medical and veterinary importance are discussed under each species.

The shrub desert formations of the Kalahari are shown to be unsuitable habitats for most species of ticks; only a few are able to survive under severe desert conditions.

In medical respects, Ornithodoros moubata (Murr.), as the transmitter of relapsing fever, is the most important tick in the Protectorate. It has been found in the eastern part up to Francistown and in Ngamiland and near Tsane; its further distribution has not yet been established. Larvae and nymphs of various members of the Ixodidae infesting domestic and wild rodents are potential transmitters of tick-bite fever.

Cattle in the eastern area and in Ngamiland were found to be infested by ten species, of which Amblyomma hebraeum Koch, Hyalomma rufipes Koch, H. truncatum Koch, Rhipicephalus appendiculatus Neumann, R. evertsi evertsi Neumann, R. simus simus Koch and Boophilus decoloratus (Koch) are the most important ones, both in respect of the numbers infesting cattle, and of their significance as transmitters of redwater, anaplasmosis, heartwater and sweating sickness.

Sheep, goats, pigs and horses were found to be infested by nine of the species listed above as occurring on cattle.

Dogs were mainly parasitised by Rhipicephalus simus which outnumbered by far the two recognised dog-ticks, Rhipicephalus sanguineus sanguineus (Latr.) and Haemaphysalis leachii leachii (Aud.).

Wild Bovids and zebra are infested by species which also live on domestic ruminants, but the percentage of the different species present varies according to the host and to the locality.

Wild carnivores are infested by the same species as are dogs, but in this group, too, there are differences in the relative abundance of the various tick species.

Small birds are hosts of immature stages of Amblyomma and Hyalomma species. Their importance as carriers for the dispersal of cattle-infesting ticks is noticed.

The cotton stem moth, Platyedra vilella (Zeller), was not known to occur in the United States prior to 1951. In August of that year, larvae of the species were found infesting hollyhock plants at Mineola, New York, by J. H. Maheny, a plant quarantine inspector of the port of New York. Adults were reared from additional material collected the following year, an indication that the species had become established. How or when P. vilella was introduced has not been determined, but doubtless it was only recently.

Diparopsis watersi (Roths.) is a serious pest of the cotton crop in the Gash Delta of the eastern Sudan. The climate and method of cotton cultivation are described briefly and a general account of the incidence of D. watersi during the season is given. Earlier work in the Sudan on this bollworm was mainly centred in the Northern Province and there is little information on the history of its occurrence in the Gash Delta. The aspects of its biology considered here include its egg-laying and larval habits, and duration of the pupal stage.

The majority of eggs were laid on the younger and more accessible plant growth. The period of wandering in search of food after eclosion from the egg was of short duration with normal egg placement, the emerging larvae had little difficulty in finding suitable food, and mortality from failure to do so was low on healthy plants. Depth of pupation did not vary greatly with soil type; the majority of pupae were found within one inch of the soil surface, and none at a depth greater than three inches. Only when the soil was a heavy clay that had baked hard following the rains, did the emerging moths have difficulty in passing through it and ascending to the surface.

The proportion of larvae forming diapause pupae increased amongst field-collected larvae as the season advanced, and in successive generations bred in an insectary from the non-diapause fractions of the preceding generations, but at no time was there a complete cessation in the production of non-diapause pupae and infestations persisted as long as there was actively growing cotton. This persistent activity in the Gash Delta is contrasted with the restriction of D. watersi to a six months' season in Nigeria. The emergence of moths from diapause pupae was not completed during the season following that of pupation, but extended for at least two further seasons; approximately 35 per cent, of the total diapause pupal population was still alive and present in the soil after the first season's emergence. In any one season the emergence was bimodal, the two peaks of emergence, which were of similar magnitude, occurring in September-October and mid-November to mid-January. When diapause pupae were kept in the laboratory and thus exposed to less extreme temperatures than in the field, the emergence was distinctly unimodal, with maximum emergence during September. The bimodal emergence observed in the field is considered to be a result of external environmental factors that inhibit pupal development at certain times of year, and emergence data from diapause pupae exposed to different climatic conditions suggest that high soil temperatures are such a factor. The pattern of moth emergence from diapause pupae in the Gash Delta is compared with that found in Nigeria and Nyasaland.

Natural mortality of D. watersi is discussed, and certain larval parasites, notably an un-named species of Apanteles of the ultor Reinh. group, and Bracon brevicornis Wesm., are considered to be of importance.

The study of the biology of D. watersi has emphasised the difficulties in controlling this bollworm, and stressed the importance of attempting to destroy it in the diapause state, preferably during the “ dead ” season. It is considered that mechanical cultivation, of the soil may provide a means to that end.

Records of Leucoptera coffeella (Guér.) from Kenya and Tanganyika have been found to be based on misidentifications and to refer to a distinct species, Leucoptera meyricki Ghesq. Other records of coffeella from the Old World seem open to doubt and require to be reinvestigated since they may also be based on misidentifications. L. coffeella seems likely to be a Neotropical species predominant in the West Indies. A lectotype is designated for meyricki, but the type material of coffeella cannot be traced and the identity of the latter species remains to be properly established. The present generic assignment of meyricki and coffeella in the genus Leucoptera Hübn. needs to be reconsidered in the light of the new genus Perileucoptera Silvestri (1943).

Two areas in Ankole, Uganda, were studied with a view to obtaining estimates of the standard availability of Glossina morsitans Westw. These estimates gave maximum and minimum fiducial limits of 2·0 and 0·19 per cent. These are considerably lower than the estimates, obtained by Jackson in Tanganyika, of approximately 10 per cent. This difference is of practical importance in that a single fly caught in Ankole indicates a much larger population, and this is the probable explanation of the trypanosomiasis problem round the edges of the flybelt, where routine catches showed flies to be scarce.

Several artificial media were tested in an attempt to eliminate the use of human faeces as oviposition and early larval habitats for breeding Musca sorbens Wied. in the laboratory. Eggs, laid on cotton-wool pads moistened with diluted milk or, preferably, on small quantities (10–15 g.) of human excrement, were transferred to the breeding medium. The best of those tested was a mixture of coarse wheat bran (120 g.) and diluted milk (240 g.), which yielded normal healthy larvae and adults. The average weight of a puparium produced in this medium was somewhat less than that of one produced in human excrement.

Replicated sample plots of wattle (Acacia) were sprayed from the air with 2 oz. endrin and 1½, 2¼, 3 and 6 lb. toxaphene per acre, each in light diesel oil, to test the effect of these insecticides on the bagworm, Kotochalia junodi (Heyl.), and other wattle fauna. All invertebrates which fell from the sample trees were collected on sheets at intervals after spraying and identified. The mortality of bagworms was assessed after 10 to 14 days.

The mean corrected mortality was significantly lower in the treatment with 1½ lb. toxaphene than in the others, which, however, did not differ significantly amongst themselves. In all cases the kill was greater in the upper than in the lower parts of the tree crowns. There was no difference in the final percentage “fall-off” of bagworms in all plots, though in those treated with endrin the initial rate was higher. A very high kill, ranging from 96·6 to 98·5 per cent., was obtained in all but the 1½ lb. toxaphene plots, but even the 6 lb. application was not sufficient to reduce the bagworm population to its endemic level.

The arthropods, other than bagworms, collected on ground sheets are listed by Orders and Families and also classified into groups as beneficial, indifferent, and harmful. Nearly two-thirds of the total were found to be beneficial.

The object of the work described in this paper was to compare adults of Oryzaephilus surinamensis (L.) and O. mercator (Fauv.) by morphological and biometric methods with a view to determining the status of the latter as either a variety of O. surinamensis or as a separate species.

There are some marked and constant differences between the two insects in the structure of the male genitalia. These are listed.

The analysis of the biometric results shows a clear-cut difference between the two insects in the ratio of eye length to temple length. All the other ratios considered overlap, although the means may be widely different. Some of these ratios are illustrated by histograms.

A cross-breeding experiment gave no offspring from the mixed pairs.

It is concluded that O. mercator is a good species which can be recognised morphologically.

The inheritance of aldrin resistance in the Indian house-fly, Musca domestica nebulo F., was studied by making reciprocal crosses between individual as well as groups of flies of an aldrin-resistant and a non-resistant strain of the subspecies at 28±1°C. The offspring of all the families thus formed were tested by the topical application of constant-volume drops of various concentrations of aldrin solution in oil to the dorsum of thorax of groups of flies. Mortality counts were made 24 hours after treatment. The results obtained indicated a multifactorial heredity for aldrin resistance in M. d. nebulo. The phenomenon was found not to be sex linked.

The two weevils associated with the living stems of the banana plant in Uganda are Cosmopolites sordidus (Germ.) and Temnoschoita nigroplagiata (Qued.); the damage caused by the former has been known for many years but the latter, which usually breeds in rotting stems, has only recently been shown to attack living ones. T. nigroplagiata occurs in every banana-growing area in the territory and is particularly abundant in some parts of western Uganda where C. sordidus, which is otherwise widespread, is rare or absent. Other species of Temnoschoita associated with the banana plant that occur in Uganda but that are rare, are T. basipennis Duv., bred from larvae in rotting pseudostems, and T. erudita, Duv., known only from the adult.

The full-grown larva of T. nigroplagiata is described in detail and characters are given for separating the larva and pupa of this species from those of C. sordidus.

Winged and wingless individuals of Myzus persicae (Sulz.), when offered a choice between unsprayed cauliflower seedlings and seedlings sprayed with a 0·1 per cent. aqueous solution of Lissapol N (a non-ionic wetting agent), preferred Lissapol-treated plants. This effect was statistically significant.

Further experiments showed that Aphids similarly preferred treated turnip seedlings to untreated seedlings. The preference for sprayed cauliflower seedlings was also shown when an anionic, a cationic and a mixed wetting agent were used.

Experiments were carried out in the laboratory with individually marked females of Glossina palpalis (R.-D.); various aspects of their mating behaviour, when placed with virgin 7-day-old males, were studied.

Using virgins, females 1–3 days old mated for an average period of about two hours, females 4–9 days old for about 75 minutes, and 10-day-old females for somewhat less than one hour.

Using virgins, mating was found to be relatively infrequent in 1-day-old females, maximal in females 2 and 3 days old and thereafter decreased as the age of the females increased.

Females up to 10 days of age were found to be willing to mate on a number of occasions; re-mating was more frequent among the younger flies. The number of older females of G. palpalis which are prepared to re-mate is very small.

Previously mated females of G. palpalis were shown to be less willing to mate than virgin females of the same age. It seems that this is due to a decrease in desire for mating by the females rather than a loss of attractiveness to males.

The implication of these laboratory findings, in relation to fly behaviour in the field, is discussed. It is suggested that a considerable proportion of young females of G. palpalis is prepared to re-mate in nature, on a number of occasions, but that the desire for mating is extinguished much sooner in life in mated females than it is in virgin females.

The mosquitos of two villages on the Kenya coast were studied over a period of two and a half years, which included years of very light, average and very heavy rainfall. A survey was made of the species occurring in the bush and in the houses, and in addition 24-hour biting catches were done and window-trap catches were examined to obtain information on the movement of species in and out of houses.

Sixty five species were taken in net catches in the bush but only 19 were taken regularly; five (Taeniorhynchus uniformis (Theo.) and T. africanus (Theo.), Aëdes woodi Edw., Culex invidiosus Theo. and C. guiarti Blanch.) were abundant. In the houses, two species, C. pipiens fatigans Wied. and Aë. aegypti occurred regularly, the former being abundant and the latter not uncommon. Anopheles gambiae Giles and A. funestus Giles were seasonal; A. funestus appeared only after exceptionally heavy rain. The in-going window trap attracted only an occasional mosquito seeking shelter during the day and only six species were taken. Thirty species were found in the out-going trap but only seven occurred regularly. A. gambiae, A. funestus, T. uniformis, T. africanus and C. p. fatigans were most active during the hours of darkness, with the main activity in the four hours before dawn. Aë. aegypti had two waves of activity, in the four-hour periods before dawn and before sunset, respectively; the sunset peak was higher and the main activity probably occurred between 18 and 19 hr., as previously recorded for this species in Mombasa.

Thirty five species were taken biting in the 24-hour catches in situations designated bush, house and compound, respectively. The biting cycles of A. gambiae, Aë. aegypti and C. p. fatigans have been compared in the three situations. The biting rhythm of each species was much the same in the different environments but the time and magnitude of the main peaks varied. In the case of Aë. aegypti, which probably includes two different forms, there is a marked difference in the magnitude of the evening peak in the bush and house. The biting cycles in the bush are given for A. squamosus Theo., T. uniformis, T. africanus, Aë. fryeri, Aë. metallicus (Edw.), Aë. albicosta (Edw.) and C. antennatus (Becker) and their occurrence in the other two situations is noted. The cycles of T. uniformis and Aë. fryeri agree with previous findings, but that of T. africanus differs from other cycles recorded for this species by having the main biting after midnight. The remaining species were rare, but one catch of 274 specimens of A. funestus was recorded.

Resting mosquitos were more numerous in the second half of the year from August to December, a period of light rainfall and high temperatures. Biting mosquitos were more commonly taken, especially in the bush, in the second quarter of the year, during the main rainy season. The biting activity of some species increased in the houses in the second half of the year, when there are high winds, and biting in the bush was minimal.

During 1955 and 1956 two attempts were made to eradicate Glossina, palpalis (R.-D.) and G. tachinoides Westw. from 8¼ miles of heavily forested perennial river in Benue Province of the Northern Kegion of Nigeria by using DDT.

Descriptions of the rivers and the means employed in applying the DDT using knapsack sprayers are given, together with the effect of the insecticide on the fly population.

It was found that it was possible to eliminate G. palpalis from this type of habitat, where the forest is largely restricted to the immediate vicinity of the rivers, but that isolation must be carefully undertaken to prevent reinvasion, which would appear to be more extensive than had been expected. G. palpalis was completely absent for 18 weeks.

G. tachinoides, which was present in much smaller numbers, also disappeared on the treated river, but because of a similar disappearance on the control river it is not possible to attribute this to the insecticidal treatment.

The cost of spraying was about half the cost of clearing by normal current methods.

Using laboratory tests described, the effectiveness of a number of insecticides on both larval and adult, fully engorged examples of the Blue Tick, Boophilus decoloratus (Koch), was determined. The results of tests using adult ticks were expressed as histograms of the percentage control exerted by varying concentrations of insecticides. The test using larvae was more sensitive and enabled results to be expressed as dose-response curves from which the LC50 could be accurately calculated. By comparing ticks from different localities in South Africa, resistance to a number of insecticides was demonstrated. Adult ticks from the farms Allandale and Ferndale in the East London district were three to four times more tolerant of sodium arsenite than were the sensitive ticks from Frankenwald farm near Johannesburg. Both larval and adult ticks from Ferndale and Allandale, when compared with Frankenwald ticks, were highly resistant to γ BHC, which conferred some cross-resistance to toxaphene, chlordane, dieldrin and aldrin. Ticks from Allandale, in addition to being resistant to sodium arsenite, BHC, toxaphene, chlordane, dieldrin and aldrin were highly resistant to DDT. DDT resistance conferred a cross-resistance to Dilan.

The organo-phosphorus insecticides tested, malathion and diazinon, were equally effective against all ticks.

An account is given of the damage caused by adults and larvae of Brontispa longissima (Gestro) to the young unopened fronds of coconut palms in the British Solomon Islands. Normally, only young palms less than 10 years old are severely attacked, but this has interfered seriously with replanting programmes. Full-grown palms suffer severe damage only occasionally; reasons for this difference in susceptibility are suggested.

Earlier reports, that seedlings of Malayan type are more readily and severely attacked than those of Samoan or local origin, were confirmed. A fertiliser treatment had no effect on the growth of the palms or the amount of damage by Brontispa.

Laboratory tests showed that the deposit from a spray of 0·2 per cent. p,p′DDT was completely effective for three–four weeks, that chlordane (0·16%) became significantly less effective in the third and fourth weeks, and that dusts of DDT, alone and with BHC, showed signs of diminished efficiency in the fourth week.

In small-plot trials with sprays of DDT or chlordane, applied at various concentrations and frequencies, the effects of treatment were assessed by counts, at suitable intervals, of living and dead examples of Brontispa, by estimating damage to the youngest open frond, and by measuring the growth of seedlings. DDT at 0·1, 0·2 and 0·3 per cent. of p,p′isomer, and chlordane at 0·08, 0·16 and 0·24 per cent. gave very satisfactory control of a heavy attack of the beetle and suppression of damage. Applications at 10-day intervals were more effective than 3-weekly ones. Similar trials with dieldrin at 0·1 per cent. and DDT at 0·3 per cent. against a light attack were completely effective.

In further trials, direct comparisons were made between DDT at 0·25 and 0·025 per cent., chlordane at 0·16 per cent. and dieldrin at 0·15 per cent. applied at both fortnightly and monthly intervals. The lower concentration of DDT was much less effective than the other treatments. DDT at the higher concentration and dieldrin were equally effective when applied at fortnightly intervals, but at monthly intervals the latter was superior in control of immigrant beetles. This is attributed to its greater persistence. It is concluded that, in the formulations used in this trial, dieldrin is superior to DDT and chlordane.

Further trials with dieldrin at 0·15 per cent. showed that palms subjected to only moderate reinfestation were adequately protected by spraying every six weeks, whilst isolated areas of young palms may be left much longer, probably several months, once the initial population has been controlled. The maximum frequency, under the most adverse conditions, might vary between 2 and 4 weeks, initially. Varietal susceptibility in the coconut does not affect the efficiency of control.

Slight phytotoxicity, indicated by retardation of growth and rate of production of new fronds, was caused by frequent applications of high volumes of spray, but the volume necessary to produce such effect is considerably in excess of that required for satisfactory control. Unnecessarily high volumes and concentrations should, however, be avoided.

The spray was applied to each palm, individually, downwards on to the central spike, where the beetle lives. Equipment capable of delivering a fine, low-volume spray controlled by an efficient trigger tap will use only about 16 cc. spray per palm up to 3 years old. With a low-volume atomiser, this consumption can be reduced to about 6 cc.

An imitation aerial spray gave promising but inconclusive results.

With the proprietary formulations of insecticides used, the addition of a wetting agent was unnecessary.

Field applications were tried out in the Russell Islands on extensive areas of young palms that showed heavy beetle attack. Sprays containing dieldrin or DDT, each in two proprietary formulations, gave excellent and satisfactory results, respectively.

It is concluded that the experiments clearly indicate that very satisfactory control can be achieved at low cost, and that a programme of replanting could be safely embarked upon without fear of the severe losses, due to Brontispa, that have been suffered in the past.

Six types of habitat in papyrus (Cyperus papyrus) swamps in Uganda were studied with regard to the production of mosquito larvae. A classification, of the types is given, which was largely based on the lapse of time since temporary clearing by cutting or burning had been carried out.

Altogether a total of 5,781 larvae belonging to 17 species was studied. Culex (Culex) guiarti Blanch., C. (C.) univittatus Theo. and C. (Neoculex) rubinotus Theo. were the dominant species, comprising together 78 per cent. of the total number of larvae. Anopheles gambiae Giles was not recorded. Samples of larvae were taken at intervals between mid-January and early April 1957. The sampling method used was unsuitable for those species of which the larvae obtain air from roots or stems of submerged vegetation, and these were excluded from the present study.

There was considerable variation in species and numbers of larvae and in their frequency in the different types of habitat.

It is concluded that (a) peripheral zones, especially in natural untouched swamps, are much more productive than the interior, (b) where swamps have been altered by cutting and by burning of papyrus and other vegetation, burnt habitats, whether recently or after the lapse of up to four or five months, have a very low productivity, (c) of the six chemical factors investigated (pH, K, Na, absorbed oxygen, free and saline ammonia and albuminoid ammonia) only the quantity of soluble organic matter, indicated by absorbed oxygen, and albuminoid ammonia, showed any relation to productivity, the least productive habitats containing the smallest quantity of organic matter.

Other possible factors in swamp water, which were not investigated, are mentioned. These are (a) the nature of soluble oxidisable organic matter, (b) conductivity, (c) ferruginous surface films and (d) iron in solution.

An improved technique is described for the preparation of permanent mounts of small Arthropoda and Nematoda, using a phenol-balsam mounting medium; a method is also described for clearing live, or freshly killed, specimens in strong chloral hydrate solution. The essential feature of the mounting method is the transfer of the specimen to a slide, in a drop of phenol, to which dry, powdered balsam is added and allowed to dissolve in situ. The mount is then dried and later covered in the usual fashion.