SOUTH AFRICAN BAGWOEMS. 633 



average being about 2300. This enormous amount of eggs 

 is apparently necessary to counteract the great mortality 

 amongst the young at the time of their distribution. 



In those groups where the females leave their bags, but 

 remain attached to it, the eggs have been observed to be laid 

 on the outside of the bag. It has been claimed for a certain 

 species of bagworm with similar habits that the eggs were 

 deposited inside the bag by the female thrusting her ovi- 

 positor through the neck of the bag, but we have thus far 

 not been able to observe any such procedure on the part of 

 these bagworms ; the eggs were always laid on the outside 

 of the bag or on the bottom of the breeding cage. 



In the case of the females of the fourth group, which have 

 well -developed wings, it appears that the eggs may be 

 deposited anywhere, as we have found them usually on the 

 bottom of the breeding cage in which the moths were confined. 

 The fecundity of these actively flying females is much less 

 than that of those moths which remain in or on their bags. 

 In the former case such an enormous reproduction is not 

 required, as the female can do her share in the distribution, 

 and the eggs are deposited in places where they are concealed 

 and on or near the food-plant of the young caterpillar. In 

 the case of the confined females the young play an entirely 

 passive role in their distribution (the wind being the principal 

 agent), and are thus subject to numerous vicissitudes with a 

 more or less remote chance of their being transported to a 

 suitable food-plant, while with the species in which the females 

 are active this distribution has already taken place before the 

 young have hatched, and they at once find their food ready 

 for them. The mortality amongst these is thus apt to be very 

 much less than in the former case, and a gi^eat productivity 

 on the part of the female is not therefore so essential. In 

 fact, it would probably be unfavourable, as the heavy mass of 

 eggs might impair the flight of the parent, and thus restrict 

 the area of distribution. 



