The red spider, Oligonychus coffeae (Niet.), persists in all stages of its development on a few old leaves and ‘ janams ’ (small leaves at the base of the shoot) of tea bushes during the cold weather, and this persisting population is primarily responsible for the attack in the spring.

In pruning, a great many of the old leaves (including janams) are removed from bushes, and, concomitantly, the red spider. Pruned tea is, therefore, less attacked than unpruned tea or ‘ skiffed ’ tea (where just a little is cut off the tops of the shoots) in which comparatively more leaves are left on bushes.

Sweet corn (Zea mays) is frequently attacked by Oscinella frit (L.) in southern England because the optimal sowing date (1st–20th May) determines the appearance of the seedlings at the peak of the spring flight (13th–30th May).

A Latin-square experiment including three Thimet treatments and controls showed that almost complete protection could be given by seed-furrow and surface placements along the rows of an 8 per cent, granular formulation at the rate of 2 lb. actual Thimet per acre.

The crop on the untreated control plots was more than halved by the naturally occurring infestation of 45 per cent, of the primary shoots.

Estimation of Thimet residues in cobs taken from the seed-furrow treatment showed that only a very minute trace of toxic material was present.

Tasting tests on cobs from treated plots revealed no detectable taint.

Glossina medicorum Aust. was collected in considerable numbers in thicket near to Accra, Ghana. The habitat was unusual in that the thicket rarely exceeded 15 ft. in height and big trees were entirely absent. Grassy open spaces within the thicket provided the feeding grounds and a list of possible hosts is given.

There was some suggestion of an association between the abundance of flies and the rainfall in 1958 but noti in 1959, while the size of the flies was inversely correlated with the saturation deficit.

Large-scale operational trials of dieldrin lattices applied by aircraft for controlling hoppers of the red locust, Nomadacris septemfasciata (Serv.), were carried out in the North Eukwa outbreak area in south-western Tanganyika during 1958 and 1959. Single swaths of dieldrin aqueous emulsion spray were applied by aircraft to vegetation at wide intervals and in two directions at 90°, forming a rectilinear lattice distribution of poisoned strips of vegetation over large, hopper-infested areas. Hoppers, especially those in bands, were killed on eating the poisoned vegetation in the strips which they encountered during their migrations. An accurate method of lattice layout by aircraft pilots without assistance from ground marking parties was developed, and the whole operation was used on a large scale for controlling the hopper infestation in North Eukwa in 1959.

In the summer of 1958, experiments were conducted in the vicinity of Brunston Muir, Midlothian, 11 miles SE. of Edinburgh, to measure the flight range of Culicoides impunctatus Goetgh. from its breeding site in the direction of the prevailing south-westerly wind. Thirty-six sticky traps were exposed for six weeks from 27th May to 7th July and captured 23,211 specimens of Culicoides, of which 20,105 were of C. impunctatus (7,207 males and 12,898 females).

Eleven of the traps were arranged in a line over 1,200 yd. The catch of females did not alter for 400 yd., then decreased to a new level which remained constant from 600 to 1,200 yd. This decrease was associated more with the absence of livestock after 550 yd. than with any density/distance regression. The male distribution was similar to that of the females.

Ten more traps stretched over 750 yd. and again no regression was discernible. The female distribution was affected more by the availability of hosts than distance from the breeding site. The male distribution here was different. They appeared to pass less readily through a gap in a narrow belt of woodland than did the females.

The distribution and biology of two related species of mosquito, Mansonia (Mansonioides) africana (Theo.) and M. (M.) uniformis (Theo.), have been compared. M. uniformis is found from China to Africa, whereas M. africana is restricted to the continent of Africa. The two species do not interbreed although mating, but no insemination, is possible in the laboratory. Strains of M. uniformis from Africa, Ceylon and Malaya are interfertile, but crosses between the African and the other strains, especially, showed a reduction in fertility of the eggs produced and thus some evidence of speciation.

The two species show the same adult behaviour at mating, feeding (both in the field and in the laboratory) and during oviposition. Both species are stenogamous and mate readily in small cages. The first blood-meal is taken approximately 24 hours after emergence and immediately after each oviposition, 3–5 days after the previous blood-meal. M. uniformis is more active directly after the blood-meal.

In the course of a recent preliminary revision of the MIRIDAE of the subfamily BRYOCORINAE in the British Museum (Natural History), the results of which will be reported in a paper now in preparation, the genus Pseudodoniella China & Carvalho was examined. The investigation revealed that the two species, P. laensis and P. szentivanyi, both described by Miller in 1957, are definitely conspecific. Because of the importance of the species as a pest of cacao in New Guinea and Papua, a short note is published here in advance in order to clarify this problem and make available a name for biological work.

Basic laboratory investigations have been carried out on a method for giving house-flies, Musca domestica L., relatively large doses of insecticide, with a view to possible applications in controlling, or preventing the appearance of, resistant strains of flies. The principle is that a relatively large drop of mineral oil will hang on the lower end of a thin vertical or near-vertical wire (e.g., a drop of up to 3 μl. on a wire 0·3 mm. in diameter), and a fleeting contact of a fly with the drop will generally transfer to the surface of the fly a substantial volume of oil. For investigational purposes pins were inserted obliquely into rods (e.g., about 700 pins into a rod 60 cm. long), and drops of up to about 1 μl. were formed on the ends of the pins by dipping the pin-bearing rods into solutions of insecticide in oil. In a typical experiment a rod with suspended drops was hung vertically from the ceiling of a chamber into which flies were released; flies then collected doses of insecticide when attempting to alight on the rod.

In an area of sleeping sickness due to Trypanosoma rhodesiense in Uganda, Morris's ‘ animal ’ traps were used to study the activity and the relations with habitat and hosts of the vector, Glossina pallidipes Aust., a tsetse difficult to sample by conventional fly-round methods.

This type of trap was found to give samples both numerically greater and more truly representative of the tsetse population present than did either fly-boys or Chorley's bicycle screen.

Black traps showed an over-all superiority to brown traps, greatest during the rains and disappearing in the dry season, and this was related to the tsetse being attracted by the trap as representing a natural host.

The black rice bug, Scotinophara lurida (Burm.), is widely distributed in Ceylon in areas where rice is grown under irrigation. It first became a serious pest in 1940 and, periodically since, it has assumed epidemic proportions in the Southern Province where two crops of rice are grown annually. Each crop takes from 3½ to 4 months to mature, the fields lying fallow in the intervening periods. During these periods the insects aestivate, in the adult or late nymphal stages, in cracks in the bunds in the rice-fields or on neighbouring higher ground. They remain motionless for the most part during aestivation, are gregarious and occur as much as 2 ft. below ground-level.

The adults leave the aestivation sites in April and May and settle in the first crop when it is two to three weeks old, and a subsequent aestivating population behaves similarly in November and December for. the second crop. There is at first considerable flight activity at dusk, and at night, and after feeding for about a week on the rice seedlings copulation takes place and oviposition commences about ten days later.

The damage caused to cotton by the yellow tea-mite,Hemitarsonemus latus(Banks),was first seen in Uganda in 1945 and is now known throughout the important cotton-growing areas of the country. Experiments on cotton in the Belgian Congo showed that sprays and dusts of several insecticides would control or prevent infestations of H.latus;earlier published work in Ugandasuggested that BHC reduced tea-mite damage and DDT increased it,when both were appliedas sprays from wettable powders.However,tea-mite damage was not noticeable on trials in which single rows of cotton were sprayed with DDT emulsion,or on large-scale trials using DDT formulated as a water-miscible liquid. These trials were all directed against the pest insects Earias spp. and Lygus vosseleri Popp.,the standard rate of application being 1 lb. active ingredientper acre applied four times at ten-day intervals.

The size-specific fat content of tsetse flies recently emerged from their puparia was determined and by comparison with the size-specific fat content of newly deposited larvae an estimate was obtained of the consumption of fat during pupal development. Experiments with Glossina morsitans Westw. were carried out at a number of different temperatures and it was found that the amount of fat consumed was least at temperatures between 22 and 24°C.

Knowing the duration of the pupal period at different temperatures, the rate of fat consumption could be calculated and the logarithm of this rate was found to be linearly related to temperature. The occurrence of an optimum temperature in respect of fat consumption thus reflects the fact that at high temperatures the rate of fat consumption is greatly increased without a corresponding reduction in the duration of the pupal period, whereas at low temperatures the pupal period is very greatly lengthened without a corresponding decrease in the rate of fat consumption.

Indications of the type of paddy grain most commonly infested by Sitophilus sasakii (Tak.) and Rhyzopertha dominica (F.) have been obtained from the examination of infested samples of paddy grown in Trinidad, W.I., and in British Guiana.

Small-scale experiments with sound mature paddy have shown that S.sasakii is unable to feed and breed in a grain with an intact husk, even when the moisture content is high. It is also probable that R. dominica finds it extremely difficult to attack and infest such grains.

The rapid multiplication of S. sasakii in paddy is dependent on there being a high proportion of grains with badly damaged husks. Infestation can occur in grains with a slight separation of the lemma and palea, or with slightly split husks, but the adult that develops is often unable to emerge from such grains.

Using a deterministic model of a tsetse population, theoretical calculations have been made of the effect of repeated applications of a non-persistent insecticide upon a natural population. It has been assumed that the insecticidal applications instantaneously reduce the adult population, and that there is no residual effect.

For the numerical work it has been assumed a female fly has a pupal period of four weeks and an average expectation of life of six weeks and produces her first larva three weeks after emergence, and subsequent ones at intervals of one-and-a-half weeks.

Results have been calculated for kills of females varying from 50 per cent, to 95 per cent, per application, for series of up to eight successive applications, and for intervals between successive applications of from one to six weeks and also for the case when the population is allowed to become stable between applications.