SOUTH AFRICAN BAGWOILMS. 627 



on their original food-plants ; and our experience has been 

 that such as are conspicuous enough during the summer are 

 difficult to locate amongst the dry vegetation in the winter. 



(2) Thk Larv^;. 



The hagworm caterpillars are as a rule of a characteristic 

 appearance, being dull grey to dark brown in colour, smooth, 

 soft-bodied, and having the three thoracic segments provided 

 with dorsal chitinised plates ; these segments being the only 

 parts of the body which are normally exposed when feeding 

 or crawling. In a few cases the first abdominal segment may 

 also have a dorsal chitinised thickening, but usually the 

 abdomen is soft and membranous. 



In all cases where we have had occasion to observe the 

 newly hatched larva3 we found them bearing a remarkable 

 aspect and assuming a characteristic attitude. The thorax 

 is veiy large and massive, while the abdomen is slender and 

 conical, and is carried elevated at almost right angles to the 

 thorax. This pronounced durso-flexion, so very abnormal in 

 insect larvae, is probably a character ai'isingfrom the habitual 

 position of the body during the feeding period of the cater- 

 pillar ; for normally, when crawling or feeding, the bagworm 

 is attached to the underside of the leaf or stalk with the bug- 

 hanging downward, and the body is thus continually curved 

 dorsad at the juncture of thorax and abdomen. 



The continuous carrying of the heavy bag would be expected 

 to give rise to a modification in the structure of the body of 

 the caterpillar. We find that the thoracic legs which have 

 to bear the weight have become very well developed ; the 

 coxas are massive, meeting in the median line, the legs are 

 stout and the claws are strong, so as to enable the insect to 

 retain its hold. And as the bag, which is usually fairly large 

 and roomy, might slip off while hanging down, if the cater- 

 pillar had not been especially adapted to cope with this 

 emergency, we find that the abdominal and anal prolegs, 

 although not being used for locomotion, as in the case of the 



