No. fi. DEPARTMENT OF AGRICULTURB 3M 



Life History. 



The eggs of the apple-tree tent caterpillar are laid in July in the 

 form of a ring or band around some small twig, each band contain- 

 ing from one hundred to three hundred eggs. At the edges the band 

 which is half an inch or more in width is beveled down to the twig. 

 The whole band is then covered by a brownish substance which hard- 

 ens and forms a sort of varnish which conceals the individual eggs 

 beneath. 



The egg bands remain on the twigs from July until the leaf buds 

 begin to open the following spring. At about this time, however, the 

 eggs hatch and the little caterpillars crawl to some fork near by 

 where they spin a tent, small at first, but enlarged from time to 

 time as the caterpillars grow. From this tent the caterpillars go 

 to feed, mornings and afternoons, returning to it at night, and in 

 part, at least, about noon. Most of them also stay in the tent dur- 

 ing rainy weather. 



The caterpillars feed for five or six weeks before becoming full 

 grown. As this condition is reached, each leaves the tent to find 

 some protected place in which to spin a loose silken cocoon, within 

 which it transforms from the caterpillar to the adult moth, a pro- 

 fess requiring from two to three weeks. This change having been 

 completed the moth appears sometime in July, and the eggs are laid 

 from which caterpillars will appear the following spring. There is 

 therefore but one brood a year. 



Injury. 



The amount of injury caused by this insect varies with its abund- 

 ance. A full grown caterpillar will eat about two leaves a day 

 and one tentful will therefore consume from two to six hundred 

 leaves in this time. Averaging this rate of food consumption for 

 the entire time they are feeding, we find that a tent containing two 

 hundred caterpillars will consume over four thousand leaves in all. 

 A vigorous tree would probably feel this but little, but a small tree, 

 or a large one with a number of tents on it would be obliged to turn 

 its energies to the putting forth of new leaves to take the place of 

 those lost, just at the time when those energies should be devoted 

 to the maturing of its fruit. 



Treatment. 



The treatment for this insect is simple, the fact that the caterpil- 

 lars return to the tents at night making it easy to destroy these when 

 all the caterpillars are together, either by means of a torch held under 

 the tent, or better, by crushing tent and caterpillars with a gloved 



