INSECTS AFFECTING PARK AND WOODLAND TREES 



447 



oak-boring species. Their posiaon, however, is not sustained, so far as we 

 have been able to 

 ascertain, by other 

 observers, who al- 

 most invariably give 

 its food plant as 

 hickory. Mr Hub- 

 bard states that the 

 beetles make a short 

 entrance passage, 

 from the end of 

 which numerovis 



branches radiate in 

 a nearly horizontal 

 plane. These pene- 

 trate deeply into 

 the heartwood and 



Fig. 104 Gallery of ,\ J- le bo 



greatly hasten decay. The galleries 

 are blackened as in the case of other 

 wood borers, but the stain does not 

 extend far into the wood, indicating 

 that comparatively lifeless trees are 

 attacked by this species. He states 

 that the ambrosia consists of club- 

 shaped stems growing upright in dense 

 clusters. The joints are long and the 

 terminal conidia when they spread are 

 several times longer than wide. The 

 young and adults of the beetles live 

 socially in the galleries, and the pupae 

 lie free in the passages. Hubbard 

 states that the male of this form has 

 been described by LeConte as X. b i o g r a p h u s. 



Fig. 105 Ambrosia of Xyleborus c 

 Hubbard, U. S. Div. Ent. Bui, 7, 



