SOUTH AFRICAN BAGWORMS. 665 



usually from the top, and the pupa extracted. Sometimes the 

 bags are thus attacked in situ, sometimes they are torn off 

 the branches and collected at the base of the tree, there to be 

 consumed at leisure. The rodents responsible for this 

 destruction belong to two species, Mus concha and Mus 

 z u 1 u e n s i s . 



F. Diseases of the Wattle Bagworm. — The Wattle 

 Bagworm is subject to various diseases, all of which attack it 

 in the caterpillar stage. The most important of these is : 



The Bagworm Fungus — Isaria psychida? Pole 

 Evans. — This was first found by T. M. Mackenzie in his plan- 

 tation at Cramond, Natal, and has since been distributed 

 through many wattle plantations in Umvoti County and else- 

 where. The spores of this fungus, when they are attached to 

 the leaves, are eaten by the bagworm. Arriving in the 

 stomach of the insect, the spores germinate and grow, the 

 fungus threads ramifying through the body of the caterpillar 

 until it becomes a solid mass of hyphae. The caterpillar dies 

 in about five days after infection, and the body becomes 

 mummified. The fungus continues to increase until it grows 

 through the bag and appears on the outside, where spores are 

 formed as conspicuous white pustules. These spores are dis- 

 tributed by the wind and dropping on the leaves are in turn 

 eaten by other bagworms, which thus become infected. 



Those bagworms which ai'e attacked eai^ly in the season, 

 when they are still very young, die and drop to the ground, 

 and, being still very small, are easily overlooked. The older 

 caterpillars which are infected later in the season may reach 

 the stage when they stop feeding and attach themselves. It 

 is from such specimens that we usually see the fungus grow 

 out of the bags in the fall. Even of these later infected bag- 

 worms a great number drop to the ground, and we have 

 noticed in some plantations the ground covered with such 

 fungus-killed bao' worms. 



Notwithstanding the deadly nature of the fungus and the 

 progressive infection which takes place during the season, the 

 disease is not sufficient to check the pest to any appreciable 



