46 OHIO EXPERIMENT STATION: BULLETIN 198 



MAY. 



The eg-gs of the Apple Tree Tent Caterpillar, Malacosoma 

 americana, hatch in April or early May soon after the leaves begin to 

 unfold. As soon as weather conditions are propitious, the cater- 

 pillars extend a web across the nearest fork of the twig upon which 

 they were hatched. Later, other layers of silk are added, attachment 

 being made to neighboring twigs and sufficient space left between the 

 layers for the caterpillars to pass. The entrances to the nest are 

 near the extremities or angles of the web and into this shelter the 

 worms retreat for the night, also in stormy weather and when not 

 feeding. Exit to feed usually occurs once in the forenoon and once 

 in the afternoon. The blackish caterpillar has a white stripe down 

 the back and on each side of this central stripe there are a number 

 of short, irregular, longitudinal yellow lines. On the sides are paler 

 lines with spots and streaks of pale blue. The tinder side of body is 

 pale blackish. In the early morning hours or late in the evening, by 

 means of a ladder, it is possible to gather the web into the gloved 

 hand and crush the whole nest of caterpillars with one squeeze. The 

 same end can be accomplished by tj'ing a rag around a pole and 

 rotating it within the net to collect the web. Holding a lighted 

 torch beneath the nest is also a convenient means of destroying- them. 

 Special care must be taken not to scorch the bark and thus kiU 

 important branches when using the torch. Orchards that are regu- 

 larly sprayed with arsenicals for the canker worm, codling moth, 

 etc., are seldom troubled with tent caterpillars. 



The eggs of the, Forest Tent Caterpillar, J/a/acosow/a disstria, 

 also hatch with the opening of the buds. The only web made by 

 this species is a slight one, constructed by the caterpillars while very 

 young, against the side of the trunk or limb on which the nest is 

 locatad, and this is so inconspicuous that it is usually unnoticed. 

 The caterpillars often march in double column in passing from one 

 point to another. During the evening, and also in the early morning, 

 they are usually found collected in large bunches on the trunks and 

 larger branches of trees. When full grown, they are of a pale bluish 

 color, dotted and pointed all over with black. Instead of the white 

 stripe down the back, possessed Ijy the apple tree tent caterpillar, is a 

 row of ten or eleven oval or diamond shaped white spots. On the 

 sides are some more or leas broken pale yellow stripes. When the 

 colony is collected into a bunch, the mass may be burned with a 

 brisk kerosene torch, sprayed with kerosene, or crushed with a 

 club. When collected on a branch to rest or to feed, if the limb is 

 dealt a smart blow with a padded wooden mallet, the worms will 

 suddenly loosen their hold and drop to the ground as if they were 



