G54 C. B. HARDENBERG. 



A. Instincts developed in connection with the 

 distribution of the species. — Apart from the ordinary- 

 considerations which render a distribution of the individuals 

 advantageous to the maintenance of the species, a dispersal is 

 doubly necessary in the case of the Psych id a? on account of 

 the enormous productivity of the female (see later) . In order 

 to facilitate this distribution over a wide area, there have 

 been developed on the part of the larva, during its first instar, 

 three special instincts, in contrast with most caterpillars, 

 namely : 



(a) A decided positive phototropism. 



(b) An extensive use of the spinning glands. 



(c) A meandering instinct. 



(a) Phototropism . — When the young caterpillars emerge 

 from the eggs they find themselves confined in the empty 

 chrysalis-case of the female which after depositing the eggs 

 has dropped to the ground. They crawl out of the pupa- 

 case through the lower opening of the bag and move toward 

 the place ofc" the greatest light. When bred in a room, they 

 gathered on that side of the breeding cage which faced the 

 window; and when brought to the table for I'emoval to 

 breeding-cages they all crawled towards the Avindow, which 

 was soon covered with an immense number of young bag- 

 Avorms that had escaped through the small apertures in the 

 gauze with which the cages were covered. On hatching under 

 normal conditions in the plantations, this instinct prompts 

 them to go to the outside edge of the block or to the tops of 

 the trees. Where the trees have been cut down dui-ing the 

 winter for barking*, and the branches, with the bags attached 

 to them, are left lying on the ground, prepai'atory to the 

 subsequent burning when the weather becomes favourable, 

 we see the upper layers of this brushwood and the standing 

 stumps covered with bagnvorms, all as a result of this photo- 

 tropic instinct. 



This instinct I'emains, though not in so pronounced a manner, 

 throughout the feeding period of the caterpillar. As a result 

 of this we see that the tips of the trees ai*e first defoliated 



