THE CHEERY LEAF-BEETLE. 5 



season had undoubtedly been favorable to the development of un- 

 usual numbers of these beetles — as much as their native host plant 

 could support. Fm'thermore. the f oHage of the pin cherry was reduced 

 by a freeze on May 27, and perhaps in a part of the range by tent 

 caterpillars also. Similar conditions were probably responsible for 

 the outbreak in Michigan. These conditions induced a migration 

 which was given direction by a strong wind that blew from the south- 

 east and south on June 5, 6, and 7. It is probable that the majority 

 of the beetles had emerged from hibernation and had been feeding 

 for some time before their advent in the grape belt, for an outbreak 

 was reported from Jamestown, N. Y., about 25 miles south of Lake 

 Erie, as early as May 12. 



Within a few days after their arrival the numbers of the beetles 

 began to decrease in some orchards, and in two weeks this was gen- 

 eral. By the latter part of June practically all had disappeared from 

 the orchards, although a few scattering ones were found as late as 

 early August. 



CAUSE OF INCREASE OF BEETLES. 



The increased numbers of the cherry leaf-beetle may be attributed 

 to an increase m abundance of its natural food plant, the pin cherry. 

 This tree springs up rapidly along roadsides and in cut-over or fire- 

 swept forest land which has been left uncultivated. Such lands cover 

 wide areas in western Pennsylvania, and furnish ideal breeding con- 

 ditions for the beetle. A typical view of such a situation is shown 

 in Plate I. 



FEEDING HABITS AND DESTRUCTIVENESS. 



The adult cherry leaf -beetle feeds almost exclusively on the under- 

 side of the leaves of the plants attacked (PL V, C, D), eating small, 

 irregular holes through the lower epidermis and parenchyma and 

 sometimes through the entire leaf. These holes may join one 

 another or come so close together as to skeletonize the leaf. In a 

 few days after feeding, the upper epidermis thus exposed dries and 

 falls out, and, in case of severe injury, the whole leaf dries, and 

 defohation ensues. To an extent it feeds also upon the fruit of the 

 cherry, scarring and pitting it. (Pis. Ill, IV.) 



On cold days and at night the beetles crowd on the upper surface 

 of the leaves, and hence have given the impression that they feed 

 there. Occasionally the "VM:-iters have found beetles feeding on the 

 upper surface of peach leaves, usually those attacked by leaf curl, 

 and once on the upper surface of cherry leaves. The misapprehen- 

 sion in regard to their feeding on plum has been discussed in an earher 

 paragraph. The shot-hole fungus, responsible for ■ this mistaken 

 belief, also attacks other stone fruits which the beetle attacks, and 



