242 Some East African Insects of Economic Importance 



importance to the Protectorate, in view of the fact that there is an ever- 

 increasing area of the country under valuable crops. 



Pests attacking Coffee. One of the greatest insect enemies 

 which the coffee-grower in the E. A. P. will have to face in the future 

 is Antestia variegata. German East African authorities believe that 

 this extremely active plant bug can be combated with contact sprays. 

 My investigations w T ere tried in another direction and with some success. 

 Where the occurrence of the insect has been noticed by planters from 

 year to year, it has been found that its activity grows and wanes 

 successively. Quite accidentally I discovered that the increase in number 

 of the bugs is very largely governed by a Chalcid egg parasite. My 

 investigations were interrupted by the war, but were sufficient to prove 

 the importance of this control. The groups of Antestia eggs are laid 

 both on the leaves of the coffee bushes and also very largely on the dead 

 leaves, twigs, etc., which accumulate under the bushes. One Chalcid 

 egg is laid in each Antestia egg and the degree of parasitism is often 

 greater than 50 % of the total number of eggs. The shells of eggs 

 which have been parasitized are easily recognized by their black appear- 

 ance and by the jagged hole by which the parasite emerged. The 

 Antestia eggs which are laid on the dead leaves below are freer from 

 parasites, possibly because they are more difficult to find by the Chalcids. 

 In the plantation in which my investigation was carried out the eggs 

 laid actually on the coffee bushes were parasitized almost to extinction. 

 I suggest it might be possible to collect the dead leaves, etc., beneath 

 the bushes, to place them in receptacles and, whilst allowing the 

 parasites to escape, to prevent the young bugs from leaving by means 

 of a smear of castor oil and resin tanglefoot. The damage caused by 

 Antestia to coffee trees, by piercing the unripe berries and especially 

 by the production of adventitious shoots, through the killing back of 

 the apical buds, thus complicating pruning to a fearful extent, may lie 

 very severe. When the parasite occurs, efforts should be made, by 

 its study, to increase its intensity of action, and where it does not occur 

 to introduce it. The parasite has been sent to Mr G. A. K. Marshall 

 of the British Museum for identification. 



Scalk [nsects ox Coffee. Lecanium (Saissetia) nigrum, Niet., was 

 found at an altitude of 6000 ft . Many individuals were parasitized. 



I have examined specimens of the common scale on coffee from 

 many parts of the Protectorate, bul have found no specimens of Lecanium 

 viride all proving to he the closely related /,. africanum. 



Cut Worms and Coffee. The common cut worm is Euxoa segetum. 



