244 Some East African Insects of Economic Importance 



immune to smoke and contact sprays and were difficult to catch in 

 greasy bags on the ends of sticks. They finally disappeared completely 

 after the trees had been sprayed with a stomach poison. 



The rare butterfly, Papilio machinnoni, was unexpectedly hatched 

 out from caterpillars feeding on orange foliage. 



Eriosoma lanigera on Apples. This pest thrives in the Pro- 

 tectorate, where there are one or two old apple orchards, which are 

 not of blight-proof stock. The aphids penetrate to the cores of the 

 apples. No- winged forms have been seen. 



Orgyia VETUSTA. The caterpillars of this moth are very harmful 

 to the foliage of the quince, but the brood which was studied was almost 

 exterminated by an Ichneumon parasite. The caterpillars always 

 feed on the shady undersides of the leaves, and if violently shaken 

 from the tree during the heat of the day they die upon the hot surface 

 of the soil. 



Duomitus capensis. The caterpillars of this Cossid moth bore 

 into, riddle and kill the branches of the native tree Cassia didimobotrya. 



Pests attacking Black Wattle (Acacia decurrens). A new pest 

 of which I have never obtained the adult is the larva of what appears 

 to be a Buprestid beetle. The eggs are laid in small scale-like cases 

 on the surface of the trunk and branches; they are the only indication 

 of the presence of the insect, and the cause of the tree's death is thus 

 obscured. The flattened larvae bore in the cambium and, when numerous 

 enough, kill the tree. I found both healthy and unhealthy trees to 

 be attacked. The felling and bark-stripping of attacked trees and 

 the removal of all weakly ones seem the best method of control. Trees 

 might be girdled and, thus weakened, used as traps for the beetles 

 to lay their eggs on. 



Two allied pests in the form of a Jassid and a Capsid bug are very 

 injurious to black wattle, large areas of which they attack. Nothing 

 is known of their life-histories or natural food plants. It is not known 

 whether they ever leave the # wattle, on the sap of which they feed. 

 Instead of the trees growing up straight and quickly, they come to a 

 standstill and assume a miserable, entangled appearance, due to the 

 production of numerous adventitious shoots. Often the tree grows 

 away from this condition, but always is its growth delayed, a serious 

 matter for the wattle-planter. In the chief wattle-growing area of 

 B.E.A. the pests do ao1 occur above an altitude of 6500ft. and the 

 chief estates escape. Slow initial growth caused by weeds, drought, weak 

 seeds, bad planting and cultivation appears t<> aid these very serious pests. 



