INSECTS AFFECTING PARK AND WOODLAND TREES 



447 



oak-boring species. 'Ihcir position, however, is not sustained, so far as we 



have been able to 



ascertain, by other 



observers, who .il- 



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 numerous 



branches radiate in 



a nearly horizontal 



plane. These pene- 

 trate deeply into 



the heartwood and ^ JA A greatly hasten decay. The galleries 



are blackened as in the case of other 

 wood borers, but the stain does not 

 extcnil 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 [> h u s. 



Fig. 105 Ambrosia of Xyleborus cclsus (After 

 Hubbard, U. S. Div, Em. Bui. 7, n. s. '97) 



