84 DISEASES 



over £200 had been spent in the current year on tkeil* 

 extermination." 



The eggs of Helopeltis hatch out on the tenth day, 

 the young insects are reddish in colour, and resemble 

 small ants. Both the young and the mature insects 

 are easily recognisable by the " drumstick," or erect 

 knobbed horn, which projects from the middle of the 

 back. The insect appears to be most active in the 

 early morning, and combative measures would there- 

 fore appear to be most successful if employed at this 

 time. 



Attempts to destroy this insect at the Experiment 

 Station, Peradeniya, Ceylon, by spraying with insecti- 

 cides, gave negative results so far as it was possible to 

 judge. 



Steirastoma depressum, L. This pest has been recorded 

 as injurious to cocoa trees in the following countries : 

 Surinam, Venezuela, British Guiana, and several of the 

 West Indian islands. It belongs to the Longicorn 

 family of boring beetles, and is about an inch long by 

 half an inch broad, black with whitish-grey markings, and 

 has jointed antennae longer than the body. The adult 

 insect feeds upon young bark, small plants, or twigs of 

 mature trees. 



The female, which is slightly larger than the male, 

 lays its eggs in crevices of the bark of the cocoa tree or 

 in the angle formed by two large branches. Trees in 

 a poor state of health are more commonly 'attacked than 

 healthy trees. The eggs hatch out into grubs, which at 

 once commence boring, with their powerful mandibles, 

 into the stem tissues. The grubs grow I^ in. long by 

 f in. broad, and eventually pass into a resting stage, in 

 the form of a chrysalis or pupa. The presence of the grub 

 is usually evidenced by the fine sawdust made by its 

 boring operations which it ejects from the beginning of 

 its tunnel. When the grub is close to the surface it may 

 be cut out, but if it is too far away for this to be practic- 

 able it may be destroyed by inserting a pliable wire into 

 its tunnel. The wounds made by the grub, or in cutting 

 it out of the tree, should be painted over with the mixture 

 of tar and resin oil already referred to in this work. 



The adult beetles are active by night, but they often 

 may be found resting upon the trunk and large branches 



