288 INSECTS AFFECTING VEGETATION 



boring trees so that the young caterpillars are able to span the dis- 

 tance with their webs, there is no reason why careful banding alone 

 should not keep the trees free of this pest. If impossible to collect 

 the egg masses, spraying with arsenicals is next in order but it too 

 should be supplemented with banding and the mixture should be 

 applied while the Iarva3 are young. 



The Forest Tent Caterpillar. During the last half century 

 there have been occasional severe outbreaks of this insect in widely 

 separated sections of the United States, the hard maple being the 

 principal sufferer in the north. 



The eggs are deposited in late summer, usually upon the lower 

 branches of the tree, though they sometimes may be found upon 

 the topmost twigs. They are placed in belts of about 150 each sur- 

 rounding small twigs. After the egg is deposited, the larva de- 

 velops within the egg-shell, but does not break through until the 

 following spring, about the time the leaves are appearing. As the 

 larvae feed and develop, they do not spin a sheltering web as do some 

 of the other leaf-feeding caterpillars, but, as they pass up and down 

 the limbs of the tree, they spin a silken thread behind them, which 

 after many passages becomes a silken path. When not feeding 

 upon the leaves they rest in clusters upon the limbs and trunk of 

 the tree. They also take this position to shed their skins. 



The full grown caterpillar is about two inches in length and is 

 characteristically marked with a blue head and a row of diamond 

 shaped spots down the middle of the back. The cocoons are spun 

 in any sheltered position, such as among crumpled leaves on or 

 under the tree, in crevices of the bark and of fence-posts, etc. They 

 are composed of the hairs from the insect's body, silken threads, 

 and a liquid which the caterpillar ejects, the latter giving the mass 

 a yellow, powdery appearance. The adult is a brown moth, bear- 

 ing a darker colored band across each fore-wing, almost parallel to 

 the outer border. They fly mostly at night. Probably the best 

 method of control is spraying with arsenicals at the time the larvss 

 appear. As with the tussock moth it will probably be of advantage 

 to band to prevent reinfestation. 



The Fall Web Worm. (See insects affecting the apple.) The 

 distinguishing characteristic of this insect is seen in the large un- 

 sightly webs occuring most commonly upon wild cherry during the 

 late summer. Upon critical examination, it is seen that the webs 

 contain a quantity of hairy larvae which feed upon the more or 

 less browned leaves of the twigs enclosed. This discoloration re- 

 sults from the insect's eating the softer portions of the leaves caus- 

 ing the remainder to die. Occasionally, as the larvae approach ma- 

 turity, the food supply is exhausted within the web and they wander 

 to adjoining twigs. The pupal stage is passed in a thin cocoon, 

 usually located in trash on the surface of the ground or just below 

 the surface. Both sexes are winged moths, white, or white dotted 

 with black. The eggs are deposited upon the leaves. 



Because of the conspicuous web, one of the common methods 

 used in combating this pest is clipping the twigs from the tree to 



