The planting of cocoa in Malaya at the present time must be considered to have reached the experimental stage only, and the data obtained so far are insufficient to warrant a recommendation for its adoption either as a plantation or a small-holder's crop.

Among the large family of the Eulophidae (Chalcidoidea), the Euplectrini are closely related to the Elachertini and form with them the subfamily Elachertinae. In common with the genus Elachertus, Spin., they have antennae with a 4-jointed funicle, complete parapsidal furrows, often longitudinal furrows on the scutellum and a petiolated abdomen. They are, however, easily distinguished by the large size of the spurs of the hind tibiae, the longest being generally more or less as long as the first two tarsal joints together.

The object of this investigation was to discover the extreme length of life of nymphs and adults of Pediculus humanus corporis, de Geer, when starved at different temperatures. It is important to know this for practical reasons. Though it is impossible to complete the experiments as originally designed, it is considered that such information as has been accumulated should be recorded.

This short paper summarises and discusses the entomological results obtained from marking experiments done with Glossina morsitans at Kakoma, Tabora, Tanganyika Territory, from July 1938 to May 1940. The first eighteen months' data and results have been given in full elsewhere (Jackson, 1941) and the mathematical treatment explained. The marking experiments occupied three days weekly, and covered an area of 16 square miles of annually fired woodland and seasonal swamp; a similar area was observed in the same way for a year in country protected against fire, and in addition a number of special experiments to check results were carried out. The climate and situation of Kakoma have already been described (Jackson, 1937) for the year 1935; from that year until April 1938, smaller scale routine marking experiments were carried on with few interruptions, so that there is available a fairly complete body of data collected over nearly five and a half years.

The pineapple plantations of Mauritius have sustained since 1937 severe attacks of mealybugs (Pseudococcus spp.) which threatened to ruin the whole crop in certain localities. These attacks result in a wilting of the plants, which may be due to a toxin secreted by the bugs during their process of feeding.

1. This preliminary paper is an attempt to elucidate the intricate relationship existing between Pempherulus and its physical environments.

2. A convenient technique adapted for evaluating the effects of major climatic factors, such as humidity and temperature, in the case of Pempherulus has been described.

3. Its occurrence only in the irrigated crops is attributable to its high requirements of moisture.

4. A lengthy exposure is necessary to kill the adults in temperatures of 113° and 106°F. An exposure of 6 hours seems to kill them in 122°F. and 48 hours in 113°F. The upper thermal death-point lies roughly near 122°F.

5. The upper vital temperature limit is seen to lie near 100°F. It is indifferent to variation in humidity above 100°F.

6. Adult life is prolonged as the temperature is lowered (within a range descending from 122°F. to 91 °F.) from a longevity of 6 hours to a period of 98 days, respectively. A maximum longevity of over three months is obtained with oviposition, in a mean humidity of 73 per cent, and 91 °F. A high degree of humidity (such as 60 per cent, and 80 per cent.) is necessary in normal temperatures (such as 93°F.) for obtaining maximum adult longevity.

7. Within vital limits the optimum humidity requirements vary directly with the temperature. In 93°F. the optimum lies between 60 per cent, and 80 per cent. R.H. and in 100°F. between 80 per cent, and 100 per cent. R.H.

The Capsid bugs, Sahlbergella singularis, Hagl., S. theobroma, Dist., and Helopeltis bergrothi, Reut., have been recognised as pests of cacao in the Gold Coast for more than 30 years7,8. Whilst there has never been any divergence of opinion as to the major status of Sahlbergella as pests of cacao, this does not appear to be true of Helopeltis. Patterson (see various reports of the Gold Coast Department of Agriculture,17, 18, 19, 20) considered Helopeltis to be a major pest and indicated that damage to shoots, as well as to pods, is frequent; whereas Cotterell3 describes H. bergrothi as a minor pest of cacao and states that “damage to herbaceous shoots is of very rare occurrence.” In 1939 Cotterell6 reported that he had found another Capsid (? Bryocaropsis sp.) to be comparatively widespread on cacao around Tafo.