SOUTH AFRICAN EAGWORMS. 206 



showed little inclination to travel, and they attached them- 

 selves for pupation on the leaf on which they had been 

 feeding-. 



The Bags. — When young, the bag appears as a narrow 

 truncated cone, made up of minute particles of the food-plant 

 attached to the inner lining. With approaching maturity the 

 basal part of the bag is somev/hat constricted, and when 

 ready for pupation the larva suspends the bag at that end by 

 means of a thin strand of twisted silk, and the opening is 

 closed. 



The young bags are not stalked, but are applied with the 

 edges of their flat circular base to the leaf. The smooth, 

 conical surface offers very little resistance to the wind, which 

 might otherwise dislodge the bags. As an additional safe- 

 guard against such detachment, a couple of larger pieces of 

 leaf are attached to the mouth end of the bag in such a way 

 as to flai'e outwai-d with their edges resting on the leaf, thus 

 forming a couple of braces to steady the bag. When the bag 

 becomes larger and stronger these braces are no longer 

 required, and, as the bag is being added to from the mouth 

 end, they can still be noticed as two projections, moving 

 further away from the collar as the bag grows, becoming 

 smaller and smaller through wear, until in the mature bag 

 they can no longer be seen. 



The bag of the full-grown caterpillar is about 12 mm. long 

 by 2j mm. wide at its widest point, with abruptly rounded 

 base and truncated tip. Bag smooth, composed of silk, with 

 which are sometimes interwoven very small fragments of the 

 leaves or catkins of the oak, but in most cases these particles 

 cannot be recognised, and it appears as if the covering of the 

 bag were made of the excrement of the larva, mixed with 

 silk. Colour of bag grey, sometimes with an olive tinge. 



The bag is attached to a branchlet or the midrib of a leaf 

 by a cord of twisted strands of silk, 5 to 10 mm. long, the 

 half near to the bag being covered with the same material as 

 the bag itself (text-fig. 19, i, k). 



The bag is lined inside with a thick, tough layer of smooth, 



