192^.\ NOTES ON PROCLAIMED DISEASES AND PESTS. 183 



dull wecather. The larvae or worms tunnel under the bark of the trees 

 and consume the cambium as they move about in their tunnels. These 

 tunnels have no fixed direction, but they generally run in spirals round 

 the stem of the tree, and branches are often completely ringed. As the 

 worm moves along in its tunnel it leaves behind it excrement and chips 

 of wood and bark ; some of this waste exudes from the tunnels and 

 betrays the whereabouts of a worm, see fig. 3, 2 B. The larva is the 

 most destructive stage of the beetle it lasts for about seventy-five days. 

 When ready to turn into a pupa see fig. 2 C the larva bores in the woody 

 part of the tree and forms a small cell in which it undergoes its 

 transformation in twelve to fourteen days, see fig. 3, 1. 



Control. — Shade, both overhead and ground, keeps away beetles. 

 Spraying branches with arsenate of lead or white lime will prevent 

 beetles eating the bark and laying eggs in it, The regular use of "traps" 

 consisting of short lengths of branches with the bark on of the " Wild 

 Chataigne" tree PacJdra aquatica will attract adults and prevent them 

 from going on the cacao. 



The most important control measure is the destruction of the worms 

 and pupae in the trees. Young cacao trees especially should be 

 regularly examined and all worms and pupne removed ; dead or dying 

 branches which are sure to contain pupae and larvae are to be cut off 

 and burnt. All wounds made in cutting out worms should be dressed 

 with crude oil, a thick mixture of white lime or white lead paint. "Beetles 

 always prefer to lay in trees that have been attacked and will invariably 

 return to them if the dressing is omitted. The jorquets or forks of 

 the trees are favourite places. In districts where cacao beetles are 

 numerous all branches from trimming operations should be buried. 



A full description with coloured plates of the cacao beetle and 

 methods of control will be found in Circular No. 1 Board of Agriculture: 

 " The Life History and Control of the Cacao Beetle." (Price 6d.) 



LOCUSTS. 



Several insects come under the term locusts ; some of our local 

 species occasionally get away from their natural enemies and small 

 sporadic attacks take place. The locust that is most to be feared 

 however comes from Venezuela and is the South American migratory 

 locust Schistocerca jjaranensis. Fig. 4 represents an adult or flying 

 stage of this species and figs. 5 and 6 show the hopper or crawling 

 stages of the same species. 



Both flying and hopper stages cause damage by devouring most 

 of our cultivated plants and many wild ones as well. They are very 

 prolific and arrive in great numbers. 



Control. — The flying and hopper stages can be poisoned by the use 

 of bran mash which they eat, or the vegetation on which they feed can 

 be sprayed with arsenite of soda. If the adults deposit eggs, which 

 they do in loose soil the egg capsules can be dug up and destroyed. 

 Newly hatched hoppers can be surrounded and burnt. 



Further particulars will be found in Circular '13 Board of Agriculture ; 

 ''Locusts and Methods of Destroying them." 



