INSECTS INFESTING CROP. 65 



parasitic ichneumon fly, the Trogus atropos, which, with 

 untiring diligence, seeks them out, and puncturing their 

 bodies, deposits its eggs within them. In due course these 

 eggs undergo their appointed changes from larvae to pupse, 

 and eventually, instead of the perfect moth, a parasitic 

 fly emerges from the shell 



In some seasons great destruction has been committed 

 by some of the surface grubs infesting our various crops ; 

 acres of potatoes have been destroyed by them. The 

 stem is generally found either partially or wholly eaten 

 through, just below the surface, and in many cases the 

 tubers nearest the top have been also injured. The 

 caterpillars, or grubs, of the '"'night -fly ing moths/' 

 A gratis segetum and A. exclamationis, and also of the 

 common "crane-flies" (see page 386, vol. i.), are always 

 present on such occasions. The various insectivorous 

 birds are our great protectors against this class of 

 ravagers, whose work of destruction is always either on, 

 or close to the surface of the ground. The "crane-flies" 

 all delight in moisture, and draining no doubt has tended 

 greatly to confine their range within certain particular 

 districts. Wire worms (Materidce), millipedes (lulidce), 

 and centipedes (Scolopendrce) are all met with in the soil, 

 attacking the sound and the unsound tubers, from the 

 time they are planted until the period for harvesting 

 arrives. These, and their modes of injuring the crop, are 

 all fully described by Curtis, K6llar,Westwood, and others. 1 

 Besides these there is a vast number of other insects in- 

 festing the tubers directly any disorganization takes place 

 in their tissues, from direct injuries or from disease. Cur- 

 tis sums up his account of them by telling us " that they 

 amount to sixty or more, but probably that their name 



1 In the United States and in South America, the potato is subject to the 

 attack of a peculiar weevil the Curculio trinotatus which lays its eggs on 

 the leaves, the larvae when hatched eating into the stem, and working down- 

 wards towards the root, causing the plant to wither and decay. In some 

 seasons these insects have been very destructive to the crops. 



VOL. II. 37 



