246 Fiftieth Eeport on thei State Museum 



Life-History. 



The period required by this insect to complete its life cycle is at 

 least one year and is probably several. The eggs are deposited upon 

 the bark in June and the larvae hatching therefrom are nearly full 

 grown before winter, according to Dr. Fitch. On the other hand, 

 Dr. Packard, writing in December, 1870, mentions finding " three 

 different sizes of the larvae, evidently one, two, and three years old, 

 or more properly six, eighteen, and thirty months old." This latter 

 statement has evidently been overlooked by more recent investigators, 

 and no attempt seems to have been made to determine the true period of 

 development?; Possibly the beetle may complete its transformations in 

 one year, yet the allied round-headed borer of the apple- tree, Saperda 

 Candida, requires three. The winter is passed in the larval or grub stage. 

 Pupation occurs about the middle of April in central Illinois, and imagoes 

 may emerge from early in May until the latter part of June in that lati- 

 tude. In Massachusetts, Harris records taking living beetles repeatedly 

 from early June to the loth of July. Mr. Harrington has taken the 

 beetle June 15th in Canada. 



Associated Insects. 



An ally of the Saperda is found in Neoclytiis erythrocephalus (Fabr.).. 

 This insect appears to feed mostly on dead wood, apparently following 

 the attacks of the more pernicious species. Occasionally it occurs in 

 numbers in trees infested with Saperda tridentata. It may feed in 

 such places only on the dying tissues left by its predecessor. As an 

 evidence of its abundance, the following may be noted: From a section 

 of the trunk of an elm, three inches long and six inches in diameter, in- 

 fested by the Saperda and brought to my office about the first of Apiil, 

 eleven examples of the Neoclytus emerged between April 29th and May 

 1 2th, 1882. Large numbers of them were bred from other portions of 

 the affected tree secured later — sixteen examples on the 23d of June, and 

 others thereafter until July ist. It has also been reared by me from 

 hickory, from twigs of locust, and from pear twigs infested with XyleboruSy 

 received from Mr. Pomroy of Lockport, N. Y. It is represented in 

 figure 3 of plate VII. Another insect found associated with it in the 

 dead wood of infested elms is the Curculionid, Magdalis armkollis 

 (Say). This insect usually attacks the upper branches, but also occurs 

 with the Saperda and Neoclytus in the trunk. 



