SPOTTED APPLE-TREE BORER. 6 



FOOD PLANTS. 



At East Lansing, Mich., the writer found larvae of the spotted 

 apple-tree borer in abundance in cultivated and roadside seedling 

 apple trees and rather less abundantly in wild crab apple and Cra- 

 taegus trees. Of the three hosts wild crab apple was apparently least 

 preferred. In a letter to the author written in 1916 by Mr. A. B. 

 Wolcott, of the Field Museum of Natural History, Chicago, 111., it is 

 stated that Mr. Emil Liljeblod has taken the beetles in Illinois from 

 June 12 to July 20 on several species of Crataegus. Chittenden * 

 says: "Apple and wild crab are the only plants which it has been 

 observed to injure, but its occurrence has been noted on juneberry 

 and thorn." Slingerland and Crosby 2 give apple, wild crab apple, 

 juneberry, and thorn as the host plants. The present writer has 

 never found the species attacking juneberry. 



NATURE OF INJURY. 



The injury done by this borer is very similar to that of the common 

 roundheaded species, except that it usually occurs higher on the 

 tree. The common borer almost invariably attacks near the ground, 

 whereas the spotted species distributes its wounds along the central 

 and upper portions of the trunk and among the branches. Small 

 trees and branches, an inch or two in diameter, are most liable to 

 attack. Old wounds made by the borers are frequently marked 

 by slight swellings on the surface, having more or less of a gall-like 

 appearance. Sawdust-like castings are thrown out freely from the 

 burrows. 



The borers hatch from eggs that are placed between the bark and 

 wood at the side of punctures which the adult female makes through 

 the bark with her mandibles. As has been pointed out by Osborne, 3 in 

 some cases two eggs are placed on opposite sides of a puncture. Of 

 the numerous egg punctures examined by the writer, about half 

 contained two eggs and the other half only one. 



The larva on hatching begins to feed between the bark and wood, 

 eating out an irregularly shaped space at the side of the oviposition 

 scar, meantime thrusting most of its castings out at the opening 

 through which the egg was inserted. The burrow is usually made 

 to extend gradually away from the original scar, and, where two 

 eggs occur, the resultant larvae sometimes eat in opposite directions 

 around the branch until their burrows meet, thus forming a more 

 or less complete girdle. Toward the end of the first season or in the 

 spring of the second season the larva enters the wood, and, by means 



1 Chittenden, F. H. the larger apple-tree borers. U. S. Dept. Agr. ; Div. Ent., Circ. 32., p. 7, fig. 2. 

 1898. 



2 Slingerland, M. V., and Crosby, C. R. manual of fruit insects, p. 193-194, fig. 185. 1914, 



3 Osborne, Henry, op. cit, 



