SOUTH AFRiCAN BAGWORMS. 68S 



cause the death of the bagworms, checked theii' development 

 and produced mature insects which were below the average in 

 size. Here the maximum was 2197 and the minimum 1177, 

 with an average of 1661. This agrees closely with Fuller's 

 first figure (1600) given in 1899, his specimens probably 

 having been obtained from a locality or a tree Avhere just 

 such conditions prevailed. 



The females of the Clan Syndicate plantations were 

 gathered from a block which had suffered severely from bag- 

 worm attack for two or three successive seasons, each tiine 

 resulting in a complete defoliation, and where the conditions 

 otherwise were very unfavourable for the normal develop- 

 ment of the bagvvorm. Here we see that with an average of 

 1209 the number of eggs drops as low as 438, the maximum 

 being 1605. The maximum does not even reach the average 

 of the Wartburg lot. The Clan Syndicate bags can thus no 

 longer be considered as representing the normal reproductive 

 power of the bagworm, but are interesting as showing how 

 this function depends to a great extent on the size and vigour 

 of the female, determined by the conditions prevailing during 

 the feeding period of the larva. Apparently the bags on the 

 contents of w^iich Fuller based his later conclusions in 1913 

 were obtained from such an unfavourable area, for the years 

 1911 and 1912 were successive seasons of unprecedented 

 infestation. 



Taking into consideration the most favourable, the normal 

 and the most unfavourable localities, we come to a mean 

 average of 1756 eggs per female, which we may consider a 

 fair indication of the multiplication of the bagworm over the 

 entire area of its distribution. The actual number of eggs 

 deposited by any one female may greatly excel or fall far 

 below this average, depending on local conditions. 



(10) Life-Cycle. 



The incubation period of the eggs, judging from the time of 

 copulation to the hatching of the eggs, is about two month;, 

 the average being sixty-tw^o days. 



