THE EXTERMINATION OF PESTS 111 



one species met with in Panama is said to be con- 

 trolled by a parasitic fly. 



The principal boring insect is the palm weevil 

 (Rhynchophorus palmarum), which constitutes a 

 serious pest, notably in the West Indies, where it 

 is, however, less prevalent than it was in former 

 times. The adult is a large black weevil about 

 l in. in length, equipped with a long snout or 

 proboscis. The pupa, or chrysalis, is enclosed in 

 a large cocoon made from the fibres of the plant 

 in which the grub has developed, and is about 

 3 inches long, and Ij inches in diameter. The 

 female weevil deposits eggs in the tissues of the 

 food plant, and it is probable that wounds of all 

 kinds offer favourable situations for this purpose. 

 When the eggs hatch, the grubs bore through the 

 tissues, and, becoming fully grown, form pupae 

 within the host plant. Healthy coconut trees are 

 less liable to attack than are those in a dead or 

 dying condition, a fact which naturally suggests 

 that all dead or dying trees should be cut down 

 and destroyed as soon as discovered. Sometimes, 

 however, it may be advisable to cut the trunks 

 into short lengths and leave them on the ground 

 as traps for egg- laying beetles. Where weevils 

 are known to occur all wounds in the stems or buds 

 of the coconut trees should be plugged at once in 

 order to exclude these pests ; in Eastern countries 

 a mixture of sand and tar is used for this purpose, 



