EXPERIMENT STATION EEPOKT. 



553 



distance, in search of a place to pupate. Not that it is at all particular 

 in regard to location, for any old place will serve ; but this seems to be 

 one of the provisions for the distri- 

 bution or spread of the insect, to 

 make up for the sluggish habit of 

 the female. Where the caterpillars 

 arc abundant they often pupate in 

 masses, so that hundreds of them 

 may be found in an angle or crevice, 

 or in a narrow space. They spin 

 a few threads as a support — the 

 merest apology for a cocoon — and 

 then change to a l^rown, cylindrical 

 pupa, blunt at the head and tapering 

 to a point at the tail. In this stage 

 the difference between the sexes is 

 very noticeable, the pupa of the male 

 being much the smaller, and having 

 the antennal case broad and showing 

 the characteristic pectinations. This 

 stage lasts about ten days, a maxi- 

 mum of fourteen and a minimum of 

 seven, representing the observed extremes. 



As a rule the caterpillars feed at night and hide, or at least remain 

 quiet, during the day. It is therefore quite possible to see the trees 

 stripped, and yet at first see nothing of the insects that did it. In the 

 early stages the little caterpillars spin readily and have the habit of 

 suspending themselves by a thread. A sudden jar or alarm may also 

 cause them to let go of their support and drop for a longer or shorter 

 distance. 



Fig. 16. 



Pupa of Gypsy Moth in loose cocoon. 

 From Div. Ent., U. 8 Dept Agric. 



Methods of Spread. 



Emphasis has boon placed upon the fact that the female moth is no 

 travekT, and that under natural conditions the wandering habits of 

 the caterpillars in the later stages provide for a limited extension each 

 year. Accidental carriage of eggs, or even of adult females, by birds 

 or other animals, comes within the range of possibility, and young 

 cater]:)] liars may be carried off for some distance. But these natural 

 methods are very tedious, and the infested territory would extend but 

 slowly were they alone to be considered. 



