Specimens of the new species here described were received by the Commonwealth Institute of Entomology, London, from Mr. J. R. Williams, Entomologist of the Department of Agriculture, Mauritius, who reported it to be predacious on the Galerucid, Schematiza cordiae Barb., which has been introduced there to control the weed, Cordia macrostachya.

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.

An experiment on a semi-practical scale was made to determine the effectiveness of DDT treatment to a new house, in quelling an infestation of bed-bugs introduced with untreated furniture. Two small huts were constructed, one being finally treated with DDT, the other acting as a control. Rabbits introduced nightly represented the hosts and infested rabbit-hutches the furniture.

Forty adult bugs were introduced on the infested hutches in each hut. In the untreated chamber, the bug population soared up to over 400 in six months. In the treated hut the population remained at 10 to 20 up to the end of the experiment (28 weeks) ; these bugs remained in the untreated hutch. Translating these results to practical conditions, it appears that a bug colony might persist in an untreated bed in a room sprayed with DDT. However, the wandering bugs would be destroyed which would severely check population growth and prevent a heavy and widespread infestation.

Observations in the untreated hut indicated the decline of the first generation adults, the rise and decline of the second generation and emergence of the third.

A few preliminary tests with marked bugs proved that these insects do not usually return to the same site after going to the host to take a meal.

Aëdes leucocelaenus transmits yellow fever virus readily in the laboratory and has twice been found infected in nature.

Except in south Brazil this species is much less common than Haemagogus spegazzinii among day-biting sylvan mosquitos captured with human bait.

A. leucocelaenus has a wide distribution throughout the forested area of this country.

As a natural vector of jungle yellow fever in the northern part of Brazil it is of secondary importance when compared to H. spegazzinii.

A method is described for observing the numbers of ants foraging on the surface of of the ground by attracting them to baits of raw meat. The general area is described briefly and sites were selected for the work in three types of country.

A total of 50 baits were laid on each site in July and October. Pheidole sculpturata and P. crassinoda were the most abundant ants found on the baits. These were active mainly in the morning and evening, fewer ants were found at midday during the dry season. Comparing the numbers collected on the baits, more Pheidole were found in July than in October, and in July more ants were found on the unburnt grey soil sites than elsewhere. On the red soil sites there was a difference between burnt and unburnt country only in October, when more ants were found on the red soil in unburnt country. Pheidole is compared with three other genera of ants commonly found on the baits.

The food of Pheidole is mainly grass seeds ; some reference is made to the supply of grass seeds in different types of country and the relation between this and the numbers of foraging ants.