A description is given of the method used for the large-scale breeding of cotton stainers (Dysdercus spp.) at the Cotton Research Station in Uganda. The method entails the use of a standard cage unit, consisting of a shallow tin cylinder with detachable cloth top and bottom. The advantages of this type of unit are outlined, with particular reference to control of disease and to the other hazards of large-scale breeding.

Since the publication of the previous paper (Leeson, 1953), additional information has been accumulated on the geographical distribution of some of the Old World ticks of the genus Ornithodoros and two new species (zumpti and arenicolous) have been described. Much of this additional matter has been communicated to me by correspondents who have been kind enough to give permission for its publication here. Their names are enclosed in brackets after the new data to indicate the source and to these workers I tender my sincere thanks.

A new species of larch-feeding sawfly, Pristiphora glauca Benson, was first observed in 1950. The activities of this insect appear to be confined to the spring and early summer, and it would appear that it is one of the least widespread of the larch sawflies.

Notes on the biology of this species, including larval descriptions, are given, and field characteristics and distribution discussed. Differences in feeding habits from those of Pristiphora wesmaeli (Tischb.), with which it may be confused, are mentioned.

Between 1925 and 1947, 9,929 samples of bees from Great Britain were examined for acarine and Nosema diseases. There was a significantly lower incidence of acarine disease in English samples than in Scottish ones, but a somewhat higher incidence of Nosema disease in England than in Scotland was not significant. A decrease in the incidence of acarine disease over the 22 years was highly significant in both England and Scotland, although the rate of decrease was not significantly different between the two countries.

The average incidence of acarine disease during each month of the year was at its lowest in April, May and June, while Nosema disease reached its maximum in these three months and fell to a minimum in the autumn. Data on the seasonal incidence of Nosema disease in an apiary in Scotland between 1948 and 1953 show a similar distribution to that for Great Britain. Eesults on the incidence of both diseases throughout the year are compared with those of other authors, and possible reasons for the seasonal fluctuations are discussed.

The biting-habits of mosquitos in the genus Eretmapodites Theobald, as shown by 24-hour catches, display a certain uniformity in that all the species studied are essentially diurnal and bite very close to the ground, in shade. They do not enter dwellings.

When, however, two localities are compared (the Entebbe area and Bwamba County) it is found that there is a fundamental difference in behaviour. At Entebbe there is an exceedingly well-marked wave of activity before sunset. This does not occur in Bwamba, where the cycle shows no pronounced characteristics apart from its generally diurnal nature. It is shown that this difference arises from the fact that in Bwamba the first hour of biting-activity tends to be the most intense (no matter when it occurs) whereas in Entebbe the hour before sunset is almost always preferred.

One group (the E. chrysogaster group) is present in both localities. In Entebbe it shows an activity curve of the one type, and in Bwamba a curve of the other type.

It is concluded that some environmental influence must be involved. At the moment, however, no suggestion can be made concerning the nature of this influence, beyond the fact that the activity-patterns concerned are not easily explained in terms of microclimate.

The common Egyptian Trogoderma, T. afrum Priesner, is compared morphologically with the widespread T. granarium Everts and found to be almost identical. The two interbreed and are therefore considered to be conspecific. The morphological differences between T. granarium and T. versicolor (Creutz.) are described. These species do not interbreed.

Two Dermestid beetles, Trogoderma granarium Everts and T. versicolor (Creutz.) have been recorded on a variety of stored products. In England, T. granarium is a serious pest only in maltings. The life-history is described. The larvae are responsible for the damage to stored products, and their hairy nature facilitates the spread of infestations on sacking and clothing.

All stages in the life-cycle are resistant to heat and dryness.

A method of marking adult locusts, particularly useful when numbers are low and hand marking would be difficult, is described. It involves the use of a small hand spray gun from which a jet of paint can be directed at the locusts in spurts at ranges up to about 15 ft. The paints tested consisted of suspensions of pigments in light oil.

The paints are of low toxicity and the marks remain visible for many weeks. By the use of this method far more locusts can be marked in a given time than could be marked by hand. The efficiency of the method is reduced by high winds and dense vegetation, and it is more costly than hand marking. Most of the marked locusts cannot be recognised as such without being captured.

Some results obtained with this method in the French Sudan are given. In two months more than 50,000 locusts, Locusta migratoria migratorioides (R. & F.), were marked with a red paint; four were recovered 60 kilometres or more from the area in which they were marked, and the paint was clearly visible after five weeks.

Ways of improving the technique, and other possible methods of marking, are discussed.

Experiments in the treatment of Citrus fruit by fumigation with ethylene dibromide for the control of the damage caused by the Mediterranean Fruit-fly (Ceratitis capitata (Wied.)) were conducted during 1951–52 and 1952–53.

Jaffa and Valencia oranges were found to tolerate a concentration of 18 gm./m.3 at approximately 20°C. and exposure time of 2½ hours.

Grapefruit was found to tolerate a concentration of 15 gm./m.3 at approximately 20°C. for 2½ hours' exposure. When the exposure time is prolonged to 6 hours the maximum tolerance is 8 gm./m.3

A kill of 75 per cent. of the larvae of Ceratitis inside the Citrus fruits was obtained by exposure for 2½ hours at a concentration of 15 gm./m.3

Citrus fruit for export from Israel is normally fumigated with Decco (NC13) against certain fungus diseases. The exposure in this case is 6 hours. The possibility of combining the treatment with Decco and ethylene dibromide was examined. It was found that the treatments were compatible and that, at an exposure of 6 hours, a dosage of 6 gm./m.3 of ethylene dibromide gave a kill of up to 93·5 to 96·4 per cent.

Fumigation of fruit for export, in batches of 3,000 cases at a time, showed that 6 gm./m.3 of ethylene dibromide (all other conditions being equal) killed up to 98·5 per cent. of Ceratitis larvae (provided no gas leakage occurred in the fumigation chamber). This concentration did not cause injury to Jaffa and Valencia oranges. In the case of grapefruit, slight damage occurred—especially in over-ripe fruit (during the second half of April) which was not intended for shipping.

The effect of temperature on the life-cycle of Ephestia cautella (Wlk.) has been investigated, with emphasis on the effects of constant low temperatures and of the variable conditions of the English winter. The humidity was never low enough to have any effect on survival.

The total life-cycle (egg laid to adult) takes about 64 days at 20°C. and about 41–45 days at 25°C. on a wheatfeed-glycerine mixture.

The lowest temperatures at which the major changes in the life-cycle can be completed are:— hatching, 10° to 13°C; pupation, 8·5°C; and the change to adult, 10° to 13°C.

Large larvae are more resistant to cold than smaller larvae or eggs. The shortest exposures necessary to prevent large larvae from becoming adult are about one day at –1°C., five days at 0°C, 32 days at 5°C., or 83 days at 10°C.

Pupae can become adult at slightly lower temperatures than large larvae and also they can survive slightly longer exposures at – 1°C.

Adult moths live for a mean of 18 days at about 10°C. Below this temperature adult life is shortened by cold, until at – 1°C. moths survive for only one or two days. Adult life is also shortened at temperatures above 10°C., presumably by increased metabolism. At 35°C. adults live about three days. Copulation is infrequent at 13°C. and below, and few fertile eggs are laid at these temperatures. The highest number of eggs are laid at temperatures between 20°C. and 33°C.

Some types of joint action of insecticides described by previous authors are discussed, and experiments described on the joint action on Periplaneta americana (L.) of the γ and δ isomers, and of the γ and α isomers, of benzene hexachloride. The values of the mortalities obtained are given in tables and compared with calculations of those that would be expected according to several models of joint action in which no interaction occurs. From statistical evidence it is concluded that only one of these models, namely, independent action with a strong positive correlation of the susceptibilities to the two poisons, can give an appropriate explanation of the results. These results, however, can also be explained by suggesting that antagonistic effects play a part in the joint action of the BHC isomers investigated.

Recent taxonomic studies have recognised that Lygus pratensis (L.) consists of several species and other workers have shown that the Tarnished Plant Bug of N. America is L. lineolaris (P. de B.), a species confined to that continent. Although it is impossible to be certain what species is referred to in all of the earlier works on biology and pest incidence of L. pratensis in the Palaearctic region, evidence is given which shows that L. rugulipennis Popp. is the more important pest in this region and it is to this species that the name European Tarnished Plant Bug should be applied. Observations on the life-cycle of L. rugulipennis in England have been carried out and they show that there are normally two generations per year; the second generation becomes adult in the autumn and overwinters in this stage, egg-laying occurring the following spring. This agrees in general with that previously described for L. pratensis, sens. lat.

A method is described of applying even deposits of insecticide to leaves without detaching the leaves from the plants. The insecticide is sprayed by hand from an air-operated paint-spray gun under controlled conditions. Using this method for applying the insecticide, the persistence of DDT on living leaves and on glass plates was investigated.

A study of the development and fecundity of the Oriental Fruit Moth, Grapholitha molesta (Busck), under controlled temperatures of 60°, 65°, 75°, 85° and 95°F. and relative humidities of 35, 70 and 100 per cent, was carried out at East Lansing, Michigan, in 1950–51. The technique adopted is described. The incubation period of the eggs decreased from 7–8 days at 60°F. to 2–76 days at 94°F., increasing to 3–56 days at 95°F. A large number of eggs withstood an exposure of 40 hours at 98°F., but an exposure of 48 hours proved fatal. An exposure of 21 hours to 105°F. reduced the viability of eggs to 25–43 per cent, and increased the incubation period by 36–40 hours.

A description is given of the bionomics of Leucoptera caffeina Wshbn. in the Kilimanjaro District, Tanganyika, and of the characters that distinguish it in its various stages from L. coffeella (Guér.), together with the results of population studies of the former insect and its parasites in both shaded and unshaded coffee in 1938–40.

During the 1939 outbreak, the numbers of eggs per tree, and the number of live pupae present in samples of about 100 cocoons (estimated from te number of moths and parasites emerging) showed large fluctuations. The times between peak numbers approximated to the total life-cycle, indicating that at any moment one developmental stage was dominant.

Following crop failures due to wireworm (Agriotes spp.) attack on Little Hoos Field, Bothamsted, two experiments were made on the use of four chemicals to prevent wireworm attack on wheat. The chemicals used were BHC, technical DDT, ethylene dibromide and D-D.

Benzene hexachloride in the form of a dust containing 3·5 per cent. crude BHC was broadcast at the rate of 7·9 lb./acre crude BHC ≡ 15·2–16·0 oz. γ isomer per acre and was combine-drilled with the seed at rates ranging from 0·98–3·92 lb./acre crude BHC ≡ 1·9–8·0 oz. γ isomer per acre. It was also applied as a seed dressing at the rate of 2 oz./bushel of a dressing containing 20 per cent. technical γ isomer of BHC. DDT was drilled with the seed at 7·2 lb./acre technical DDT and ethylene dibromide and D-D were injected into the soil as soil fumigants by means of a special machine at 45·5 lb./acre and 210 lb./acre, respectively.