The construction of an inexpensive, simple, hand-drawn fumigator for field plots is described. The general principle employed is the injection of liquid nicotine under pressure into the exhaust system of a two-stroke engine, close to the port. The liquid is vaporised by the heat of the exhaust stream and distributed by it below a drag sheet at the rear of the machine.

The machine is of simple and robust construction, utilising standard plumbing fittings, angle iron, strip iron and second-hand motor-cycle parts and can, therefore, be made where only limited facilities are available.

The machine is self-contained and easily transportable as it can be towed behind a car from one locality to another. It is suitable for use on a wide variety of crops since the track is variable between 43 in. and 67 in. and the clearance between 16 in. and 34 in. With the 18 ft. long sheet used it can fumigate, in good conditions, one acre in about five hours. It is pointed out that the use of a lightweight sheet about 54 ft. long would decrease the time required per acre to about if hours and would enable the machine to be drawn by a tractor if desired; these suggestions have not, however, been tried.

The machine has been in use since 1941 for controlling aphis infestation in connection with work on virus yellows of sugar beet and has given most satisfactory results. Tests showed that a kill of 88–99 per cent, of Aphids was obtained.

It is shown that the insecticidal value to Macrosiphum solanifolii of DDT depends upon the medium in which it is incorporated. It is more toxic (4–6 times) when dispersed as an emulsion dissolved in a water-insoluble solvent (benzene) than when dissolved in a water-soluble solvent (acetone-carbitol) and dispersed as a suspensoid.

In the following pages an attempt is made to deal systematically with a number of Braconids belonging to the subfamily Euphorinae and reared by Dr. T. H. C. Taylor in the course of his investigation into the biology of the Capsid pests of cotton in Uganda. Taylor himself has discussed elsewhere (1945) the importance of the rôle that some of these Braconid parasites are likely to play in the control of their hosts.

A generation of Glossina morsitans was artificially isolated by allowing emergence for three days in the habitat of G. swynnertoni and G. pallidipes.

Most teneral flies (with chitin unhardened before their first meal) were active on day 2 to 4 from emergence. The non-teneral flies first appeared in numbers when a week old. It is possible that they were somewhat inactive while still fairly young, that is, up to two or three weeks, but this was not proved. They are definitely inactive between the first and second meals. The females, on the other hand, are much more active in the first three weeks of life than later on.

The teneral males contained about 12 mg. water, which was increased after several meals to a maximum of about 18 mg. by day 17. Fat started at a mean of 1 1/2 mg., declining to 1 mg. at the first meal, then rising to about 3 mg. at day 17, after which there was no further increase. Residual weight behaved like the water, except that it was relatively very low in teneral flies. The hungry flies which reappear after the first meal have also a relatively low residual weight.

In this experiment there was no evidence that smaller flies were at a disadvantage, as has been suspected from other work.

With reservations concerned with differences in place and time, the mean age of samples of male flies can be accurately deduced from the wear on the trailing margin of the wing. The females do not wear out their wings so quickly.

Males dispersed, in any one direction, to a mean perpendicular distance of 365 yards in a week, 484 yards in two weeks, 772 yards in three weeks, and 941 yards in four weeks.

In spite of undoubted interference by G. swynnertoni, a considerable second generation appeared.

The females and pupae in nature experienced temperatures approximating to those obtained in a screen at a standard meteorological station: they did not live in specially cool eeoclimates.

Mercury and tin amalgam were tried in mud bins, metallic bins and bamboo bins at different places in the Punjab. Mercury distributed throughout the bin at the rate of 3–4 tolas per maund of wheat proved effective in completely checking the increase of various stored grain pests. Mercury used at the bottom and top 10–12 in. layer of grains in the bin also proved fairly effective. Tin amalgam even with as high a dose as 13½ tolas per maund of wheat did not prove effective. Loss of mercury during use is very slight. Mercury has no deleterious effect on the germination or eating quality of wheat.

Mercury kills the fresh eggs of stored grain pests, but the eggs in an advanced stageof development are not adversely affected. It retards the growth but does not kill the larvae of T. granarium and Bruchus sp. It has no effect on the pupae, but affects the egg laying capacity of adults very slightly.

(1) An adhesive made from 3 or 4 parts (according to the temperature) of the coagulated latex of Carpodinus hirsuta and I part of either shea butter (from Butyrospermum parkii) or palm oil (from Elaeis guineënsis) was found to be very effective against both house-flies in kitchens and Stomoxys spp. in pig pens.

(2) In kitchens, wires (diameter 4 mm.) were treated with the adhesive and suspended over the table on which food was prepared. The wires should be renewed every three or four days when flies are abundant and once a week when the infestation is light.

(3) At Ibadan in 1943, house-flies were abundant from early March to late July; the maximum house-fly infestation of both kitchens and pig pens occurred during the second week of May. The upward trend in adult incidence first became evident in mid-February of both 1943 and 1944 and appeared to be correlated with a rise in temperature at that time.

(4) Ten wires treated with adhesive were suspended under the eaves of each pig pen. Each pen consisted of a covered pen and an open yard divided by a half-wall; a screen made of oil palm fronds was erected above the half-wall with the object of making the innerpen sufficiently dark to deter flies from entering it. About half a million flies (about 27·5 per cent. Stomoxys spp.) were trapped in12 pens in a period of 112 weeks.

(5) Stomoxys spp. (principally S. nigra, Macq.) were abundant between early June and mid-August in 1943 and between early June and late November in 1944. In 1943 there was a short dry season between 25th July and 12th September, whilst in 1944 there was no break in the rains. There is a marked correlation between rainfall and the incidence of S. nigra. Heavy rainfall soaks straw round the stock-yards, heaps of weeds, etc., which decompose and provide suitable media for larval development.