The populations of Nomadacris septemfasciata described in this paper were all of solitaria or neai-solitaria phase.Sexual maturation as measured by the developing ovaries took place rapidly though irregularly through the population. Its onset coincided with an increase in the daily number of hours of relative humidity at or above 75 per cent., and abundance of green food; Copulation, which started after the first wide-spread rain, took place before the ovaries of many females were completely mature.Caged locusts gave a mean fecundity of 183 eggs contained in 2·4 pods which is probably a minimum figure. Pods were laid at intervals of about two weeks and each was laid before the next batch had visibly developed.The period spent in the egg was at least 39 days, at most 46 days and probably 42 days. Adults appeared 67 days after the first hatchings. Both these periods are greater than those recorded in phase transiens or gregaria.Solitaria locusts were found to pass through seven instead of six nymphal instars as do gregaria. This difference seemed to be constant. The extra instar was probably interpolated between the second and third of gregaria but was not an exact duplicate of any other instar.The number of vertical dark eye-stripes is a convenient and fairly constant indicator of the instar. The number of antennal segments in the later instars and in the adult, and also the number of adult eye-stripes, is greater in the solitaria phase.Amongst the hoppers three main types of coloration were encountered and are briefly described but they could not be closely related to phase. The amount of dark pigment present in late stage nymphs was reflected in the young adult, the appearance of which is described in some detail. Subsequent changes during the dry season are briefly noted, in particular the pink of the hind wing, which becomes faintly visible within a month of the last moult.The changes in pigmentation which take place during sexual maturation are described in detail. In addition to pronounced darkening of the tegmina which completely changes the appearance of the solitaria locust, certain bright pigments are laid down which are later obscured by a general blackening. It is unsafe to classify Nomadacris septemfasciata as to phase on colour alone unless the date of capture and its relation to the breeding season in the locality is taken into consideration. Solitaria do not normally develop the general reddening of the body which is shown by migrating swarms, even when these are only transiens in phase.

Solutions of dieldrin, γ BHC, p, p′DDT and Baytex were applied topically to pregnant females of Glossina morsitans Westw. and also, in most cases, to fertilised flies over 21 days old and not noticeably pregnant, to virgin flies over 21 days old, and to males over 18 days old. Pregnant flies required about nine times as much dieldrin as young flies for comparable mortalities, and non-pregnant fertilised flies about four times as much. It was not possible to determine proper regression lines for other insecticides and classes of flies but significant increases in tolerance, as compared with that of young flies, were shown by pregnant flies to γ BHC and DDT, by old virgins to dieldrin and DDT but not γ BHC, and by fertilised flies to γ BHC and DDT. Pregnant flies and virgins showed no increased tolerance to Baytex, and old males showed none to dieldrin, γ BHC or DDT.These results are discussed in relation to aerial spraying of tsetse habitats and it is suggested that they explain some unexpected past results.

Solutions of six chlorinated-hydrocarbon insecticides in kerosene have been applied in drops of about 0·02 microlitre (µl.) to adults of Glossina morsitans Westw., 2–5 days old, one day after the first meal. This species is found to be unusually susceptible to this group of insecticides. In order of increasing toxicity they are: DDT and aldrin, γ BHC, dieldrin and endrin, Telodrin (1,3,4,5,6,7,8,8-octachloro-3a,4,7,7a-tetrahydro-4,7-methanophthalan). The LD50 of DDT was 0·0165 µg. (males) and 0·025 µg. (females), that of Telodrin was 0·00062 µg. (males). Susceptibility of the two sexes to DDT, γ BHC and dieldrin did not differ significantly. Two batches of flies tested with an interval of eight months differed by about two times in their response to dieldrin and γ BHC; but the response to DDT was unchanged. This difference was not seasonal.For practical use, dieldrin is the best and cheapest available insecticide, a fact confirmed in the field. Only Telodrin might replace it.

An experiment was carried out in a small block of mixed bush in Tanganyika in an attempt to eliminate the two resident species of tsetse fly. Glossina morsitans Westw. and G. suynnertoni Aust., by means of bait cattle treated with DDT. Small cattle were used at the rate of 100 per square mile in herds of 12 or 13 per one-eighth of a square mile. Their numerical superiority over the large game was no more than about 3: 1.The cattle were sprayed twice weekly. Originally a 10 per cent. suspension of the p.p′isomer was prepared from a commercial formulation of DDT. Later a laboratory-prepared emulsion (10 per cent. technical DDT) was used.Extermination was expected with a reduction in numbers of old male tsetse of 99·9 per cent. In practice G. morsitans was reduced by 99·5 per cent. and G. swynnerloni by 92·5 per cent.It is considered that there was sufficient immigration across the barrier clearing to account for the failure to achieve extermination of either species. It is not possible to say if extermination would have been attained in the absence of immigration.It is considered that with the insecticidal formulations now available there is not much prospect of improving on these results in similar conditions although a great reduction in tsetse numbers is possible and might stop the carrying of disease. In the dry season, after the grass has been burnt, there is better prospect of success.

Chlordiazepoxide (CDP) at 15 mg/kg produced two distinct actions in a food preference test, firstly a general appetite-enhancing effect, and secondly an anti-neophobic effect. Following acute injection of CDP the rats changed from eating predominantly familiar food to a novel food. This may signify an anti-neophobic effect of CDP. However, following 10 days of treatment with CDP, the anti-neophobic effect was abolished and the choice of familiar food was enhanced. This could be an indication of a more general appetite-enhancing effect. Hence some form of tolerance may develop to CDP's effects over 10 days of treatment which selectively abolishes anti-neophobic action whilst leaving the appetite effect further enhanced. There were no indications of tolerance developing to the actions of CDP in animals familiarized with all the test foods before the preference test was run. Hence the presence of food novelty may be critical to the observation of some form of selective tolerance.