INSECT PESTS OF OHIO SHADE AND FOREST TREES 241 



Control. Two methods of control are available for use, each 

 possessing merits according to conditions. 



For the protection of small shade trees, particularly when such 

 are few in number, hand-picking of the conspicuous egg masses 

 from the underside of the leaves, or the collecting of the clusters 

 of young feeding larvae is at once effective, inexpensive and prac- 

 ticable. Even when the larvae become larger and scattered about 

 over the tree, their striking coloration renders them conspicuous 

 and thus fairly easy to find, so that even at that stage hand-picking 

 is not impracticable if the trees are not too large. 



The second control measure is spraying with arsenicals. For 

 this purpose arsenate of lead at the usual strength, 3 to 4 pounds to 

 50 gallons of water, is recommended for application as soon as the 

 caterpillars begin feeding. The spraying method of control is more 

 thoroughly practicable in case of extensive outbreaks in forest 

 plantations or when large trees are attacked. 



THE FOREST TENT-CATEEPILLAE 

 (Malacosoma disstria Hubn.) 



The forest tent-caterpillar has never been recorded as appear- 

 ing in destructive numbers in Ohio; indeed, the only record in the 

 files of the Ohio Station pertaining to it is that of an egg mass sent 

 in 1904, which the writer identified as this species. However, it 

 has been highly destructive in New York ; Illinois has been visited 

 by it, and Ohio likely will be invaded in time. 



Description. The full-grown caterpillar measures nearly 2 

 inches in length and is sparsely clothed with reddish hairs above, 

 which gradually fade to whitish on the sides. The head is blue and 

 the general color of the body is bluish gray. Extending down the 

 middle of the back is a row of ten or eleven large diamond-shaped or 

 oval spots, one spot to the segment, and directly behind each larger 

 spot is a much smaller one. Extending lengthwise of the body, on 

 each side are two parallel yellowish-white lines. (A cluster of the 

 caterpillars is shown in Plate XXXV, Fig. 2.) 



The pupa is formed in a white or yellowish-white cocoon, spun 

 between leaves on the tree, in bark crevices, in trash on the surface 

 of the soil, or in any other convenient shelter. The pupa itself is 

 dark brown. The adults are heavy-bodied, active creatures, the 

 male having a wing expanse of about an inch and the female about 

 1% inches. In color they are buff with a brownish tinge, and the 

 male, aside from size, is further distinguished from the female by 

 the general darker coloration. The eggs are laid in masses encir- 

 cling the twigs and are covered with a grayish, frothy material. 



