SOUTH AFRICAN BACx WORMS. 209 



Female enclosed in bag and in chrysalis case, only the 

 head and part of the thoracic segments being exposed. 



Seasonal History, — Adults wei-e found emerging on 

 December 18tli and again in January. At the former date 

 larvge wei'e also found which appeared to be only three- 

 quarters grown, therefore the period of emergence of the 

 adults must be fairly long. 



Adults bred from young larvge collected in October 

 emerged in December and January, so that there may be two 

 generations a year, and there is probably a considerable 

 overlapping of the first and second generations. 



Economic Importance. — The larva is primarily a surface 

 feeder — that is, it does not eat the entire leaf, but confines its 

 depredations to the superficial layers, eating small patches 

 here and there, and apparently moving about from day to day, 

 the method of feeding being probably best described as 

 " grazing." These grazed patches may occur on the upper 

 or the under surface of the leaf, and, where those of the 

 two surfaces overlap, the leaf is entirely perforated, and we 

 thus find on an infested tree the leaves covered with irregular 

 skeletonised patches and scattered holes. 



The damage done to the tree may be very considerable; 

 on one tree I estimated that between one-quarter and one- 

 third of the leaf suiface was thus destroyed, and although 

 it was in the autumn (April), the tree was in places 

 sprouting out new foliage to replace the loss of respiratory 

 surface. This, of course, greatly weakens the tree, and 

 may account for the observation mentioned below, that these 

 bagworms appear to be confined to trees of low vitality, 

 one brood preparing the way, as it were, for that of the 

 coming season, the same tree being re-infested from year to 

 year. 



While we have found this bagworm locally injurious to the 

 oak, its economic importance is comparatively slight. The 

 species is very heavily parasitised by a small hymenopteron, 

 and, moreover, the caterpillars are subject to a fungus 

 disease, like that of the Wattle Bagworm. For the present 



VOL. 4, PART 1. 14 



