40 INSECTS AFFECTING VEGETATION 



inch and a quarter. This species is practically the only common 

 moth which might be mistaken for the Brown-tail Moth, which is 

 also pure white except the bushy brown tail, while the body of the 

 fall web-worm moth is white. Rarely, however, the fall web-worm 

 moths have the wings spotted more or less with black. The young 

 caterpillars, which seem to be almost all head and hair, at once com- 

 mence to spin their web over the foliage upon which they are feed- 

 ing. Within this web the colony from an egg mass feeds, enlarging 

 it as it becomes necessary. The webs are usually started at the tips 

 of limbs and are to be first noticed about August 1st. When the food 

 in the webs become scarce the older caterpillars scatter over the tree 

 where food is more abundant, and as soon as full grown seek a place 

 in which to spin their cocoons. The full grown caterpillars are about 

 an inch long and quite woolly, being thickly covered with long white 

 and black hairs, which project from numerous prominent black 

 tubercles. 



When the caterpillars are first noticed at work on the tips of 

 the twigs, if they seem to be abundant, it is best to spray the tree 

 with an arsenical. Arsenate of lead, five pounds to the barrel of 

 water, is best, though Paris green, at the rate of one pound to 100 

 gallons, with a pound or two of freshly slacked stone lime is equally 

 effective, but does not adhere as well. It is useless to wait until the 

 tree is covered with large webs and then spray. To be effective the 

 tree must be sprayed early in August soon after the eggs hatch. Aa 

 it is also advisable to spray at this time for the young brown-tail moth 

 caterpillars, it will be found to be good practice to spray about this 

 time every year. 



The Yellow-Necked Apple Caterpillar. During August one 

 often notices the tips of the apple limbs defoliated for a foot or two. 

 If examined for the cause of the damage either the Yellow-necked 

 Apple Caterpillars or the next species to be described, the Red- 

 humped Apple Caterpillars are found huddled together as if confess- 

 edly guilty. The larvae become full grown during the latter half of 

 August, five or six weeks after hatching from the eggs. The caterpil- 

 lar is then about two inches long with jet black head, and the next 

 segment, often termed the neck, a bright orange yellow, from which 

 the insect is named. Down the middle of the back runs a black stripe, 

 and on either side of the body are three stripes of black alternating 

 with four of yellow, the body being thinly clothed with long, soft, 

 white hairs. The caterpillars feed together in colonies and are often 

 found clustered together on a limb in a solid mass. If the limb bear- 

 ing it is jarred or if a caterpillar is touched, it at once assumes a po- 

 sition characteristic of this genus, throwing the head and tail in the 

 air with a jerk and clinging to the limb by the abdominal prolegs. 

 (Bui. 139, New Hamp. Exp. Sta.) 



The Red-Humped Apple Caterpillar. With much the same 

 habits and manner of injury as the last species and often associated 

 with it, is the Red-humped Apple Caterpillar. The name is given on 

 account of the prominent hump on the fourth segment, which, with 

 the head, is a bright coral red. The body of the full grown caterpil- 



