230 OHIO EXPERIMENT STATION: BULLETIN 332 



The pupa is dark brown and about a half-inch in length. (See 

 Plate XXXI, Fig. 2.) 



The adult is with unusual difficulty distinguished from the 

 preceding species. (See Plate XXXI, Fig. 1.) 



The eggs are oval, white, and deposited in a mass on the under- 

 side of the leaf. 



Life history and habits. — The moths fly about in early summer 

 and deposit their eggs, and the caterpillars soon hatch. During 

 the early stages of larval development the insects have the power 

 of letting themselves down on silken threads when disturbed, but 

 as they grow they lose their power and merely drop to the ground 

 if jarred or shaken violently. By late September, most of the 

 larvae are mature, whereupon they enter the soil to a depth of a 

 few inches and transform to the pupal stage. In this condition they 

 pass the winter. 



Nature of work. — The injury by this species is confined to the 

 destruction of the foliage of the host. In cases of severe outbreaks 

 the injury may amount to complete defoliation, though this occurs 

 more frequently on young than on old trees. 



Food plants. — -Plants of the family Rosaceae are more severely 

 injured than others. The following hosts are recorded in the litera- 

 ture or have been observed by the writer: apple, pear, cherry, 

 quince, linden, walnut, hickory, white oak, black oak, chestnut, 

 beech, witch-hazel, hornbeam, birch, locust, sumac, sour-wood and 

 sorrel tree. 



Distribution. — This insect occurs in nearly all sections of the 

 United States. Ecologically it is more destructive in orchards than 

 to ornamentals and woodland trees. 



Control. — When the infested trees are small and the attack is 

 not too severe, collecting the clusters of feeding caterpillars is effec- 

 tive and at the same time practicable. 



In severe outbreaks and on large trees, spraying with poisons 

 is cheapest and best. Arsenate of lead at the usual strength is 

 satisfactory. 



(Datana drexelii Edwards) 



Description. — Both the adult and the larval forms of this 

 species so closely resemble the yellow-necked apple datana that the 

 two insects are frequently confused, the similarity being particu- 

 larly great in the adults. However, after the differences have once 

 been noted, at least the well-grown larvae are fairly readily dis- 

 tinguished. The principal points of difference between the two are 

 as follows: The general body color of D. drexelii is somewhat 



