70 SYLVICULTURE IN THE TROPICS 



PT. I 



of which are perhaps the Schistocerca peregrina and 

 Acrydium aegyptium. These settle in huge swarms 

 over a country and devour everything green that conies 

 within their reach. Various methods of destroying 

 these insects have been adopted with success in some 

 places ; but their destruction, while in the winged stage, 

 is not practicable, and the best thing to do when swarms 

 try to settle over a certain locality is to scare them 

 away with noisy instruments, as by beating tom-toms, 

 old kerosene tins, etc. If possible, the pest should be 

 destroyed either while still in the egg or while in the 

 wingless larval stage. In Cyprus and Tunis the purchase 

 of eggs at so much per kilogramme has met with success ; 

 but in a country of which a large proportion consists of 

 steppe and savannah it is often not possible to dis- 

 cover the breeding grounds. The same applies to the 

 destruction of swarms of larvae "hoppers" as they 

 are called which devour the vegetation close to the 

 ground as they advance over it. On very smooth 

 ground a good deal can be done by beating them with 

 branches of shrubs or fronds of palms, as the slightest 

 injury prevents the insects from reaching maturity. 

 Trenches can also be dug across their line of march ; into 

 these they fall, and can be exterminated by stamping 

 earth on them. In a bush country a large number can 

 also be killed by setting fire to them. Attempts have 

 been made, unsuccessfully so far, to infect the swarms 

 with parasitic fungi. Care should be taken, in such 

 countries, to protect all insect-eating birds and also the 

 insects which attack them. In the Sudan it was found 

 that large numbers were destroyed by the Tachina fly, 

 which deposited its eggs in the bodies of the locusts. 

 Some of the Cantharididne or blister beetles also lay 

 their efs within those of the locusts. 1 



Non-migratory locusts and grasshoppers, as well as 

 crickets, often do considerable damage in nurseries and 

 young plantations, and should be destroyed. Here again 



1 Second and Third Reports of the Wellcome Research Laboratories, Khartoum, 

 1904 and 1906. 



