156 PESTS OF MISCELLANEOUS FIELD CEOFS. 



Tobacco Stem Borer, 



The most serious pest of growing' tobacco is a small whitish caterpillar, 

 which is found tunnelling in the main stem, causing a peculiar gall-like 

 swelling. The caterpillar enters at the axil of a leaf or tunnels down the 

 mid-rib of the leaf until it reaches the stem ; apparently it hatches from 

 an egg laid on the stem or on the leaf, but this egg has not been found. 



Having entered the main stem, it tunnels in the tissues, which swell 

 and undergo abnormal growth, producing a distinct and characteristic 

 knot. Within this swelling the caterpillar lives until it is full grown, 

 when it prepares an exit hole for the future moth and turns to the pupa 

 inside. The moth^ is a small brown insect, the wings narrow and 

 fringed, not easily distinguishable from the many small moths of this 

 family which are found in the fields. 



Tobacco is a crop of which great care is taken during the growing 

 period, so that cultivators are aware of this pest ; when they find this 

 swelling, they make a cut into it with a knife, believing that the admis- 

 sion of air will destroy the insect.^ Apparently the pest is not injurious 

 in healthy vigorous tobacco but is worst in a season of drought. It is 

 common in various parts of India and Mr. Green reports it from Ceylon. 

 Where the pest is seen so late that the emerging moths could not produce 

 a new generation in the tobacco, only plants that are useless should be 

 removed and burnt. No treatment, except perhaps that of cutting open 

 the plants, can check the insect in the stem. The pest can be looked for 

 in experimental tobacco cultivation, where varieties are grown side by side, 

 and causes a considerable amount of harm under these circumstances. 



Tobacco Caterpillars. 



Leaf-eating caterpillars attack tobacco and a small number may 



do a large amount of 

 actual damage by eating 

 holes in the leaves. The 

 most abundant of these 

 is a dark brown cater- 

 pillar, common through- 



„ ,,^ out India, which is the 



Fig. 176. ' 



Tobacco Leaf Caterpillar. larva of a common moth.* 



^ 76. Gncrimoschema heliopa. Low, (Tineidsc.) 



2 For this aud other facts about Gujarat tultivators, I am indebtedlto Puruahottam Patel, 

 first fieldmau. 



3 53. Prodenia litioralis. Boibd. (Noctuidse.) 



