220 Ajinals Entomological Society of America [Vol. XII, 



tion of brownish excrement, the burrow being kept compara- 

 tively free from such accumulations. Although most, if not all, 

 of the material excavated from the petiole is passed through the 

 digestive tract of the larva, the principal function of the burrow 

 is other than that of a place to feed since the total length does 

 not exceed double that of the full-grown larva — a condition 

 which would not prevail if it were a true feeding burrow, as in 

 the case of Bellura melanopyga (Welch, 1914, p. 102) where 

 burrow length increases with occupancy. Not only is the 

 tunnel always short, but also, once formed, it becomes brown 

 inside, and thereafter shows no evidence of further excavation. 



After a burrow long enough to contain the whole larva is 

 constructed, the caterpillar turns about and feeds mostly on 

 the upper surface of the leaf just outside the entrance. Larv^ 

 are frequently observed . on the upper leaf surface with only 

 one or two posterior body segments remaining in the burrow. 

 A very slight disturbance, however, causes rapid return. Feed- 

 ing in this position usually results in elongate surface etchings 

 which radiate from the petiole junction. Sometimes the surface 

 within easy reach from the burrow is completely denuded. It 

 thus appears that the chief function of the burrow is to afford 

 a safe retreat from which surface feeding may be accomplished. 

 This accounts for the fact that an examination of a large number 

 of inhabited petioles showed the head of the larva almost 

 invariably directed towards the leaf. As will appear later, 

 the burrow serves also as a pupation chamber. 



At no time was more than one larva found in a burrow, the 

 same being true for the pupae. Occasionally, a nearly mature 

 individual may, for some unknown reason, desert its burrow and 

 wander about over the Nelumbo leaves, ultimately constructing 

 a new burrow in some uninfested leaf or else preempting an 

 already formed one which it may chance to find unoccupied. 

 Instances were observed where such a wandering larva 

 attempted to enter a burrow already inhabited, whereupon the 

 occupant and the invader engaged in active combat at the 

 entrance, interlocking mandibles, twisting heads, and pushing 

 each other about in a vigorous manner, until the former suc- 

 ceeded in repulsing the latter, or until the invader forced an 

 entrance, displacing the original occupant. 



Effect on Food-plant. — In proportion to the numbers of 

 larvae present, the leaf of the food-plant loses its chlorophyll- 



