30 



of this genus in the timber from which casks are made are sometimes 

 responsible for leakages in casks imported from Europe into India. 



if- 



J&fffidWM fr% 



Fig. 32. 





-Ambrosia of Xyloterus retusus — greatly en- 

 larged (original). 



THE GENUS GNATHOTRICHUS. 



The males are distinguished 

 from the females by the stronger 

 development of tubercles or 

 teeth at the end of the body. The 

 young are raised in cradles, as 

 in Monarthrum and Xyloterus. 

 The only species of the genus 

 whose habits are known is 

 Gnathotrichus materiarius Fitch 

 (fig. 33), 

 of which 

 Asa Fitch gave a brief account in 1857. He gave 

 a diagram of a gallery, which shows cradles ex- 

 tending upward and downward parallel with the 

 grain of the wood. His specimens were found in 

 pine wood. Professor Hopkins also enumerates 

 this species in his catalogue of Scolytidae of West 

 Virginia, and notes that it causes "bluing" of the 

 wood, which is characteristic of the ambrosia- 

 feeding beetles. He has prepared a careful draw- 

 iDg of the gallery from which the accompanying 

 figure 34 has been adapted. There are two other 

 species in our fauna, of which little is kuown. 



Gnathotrichus asperulus Lee, a small species resembling the twig 



Fig. 33.— Gnathotrichus ma- 

 teriarius (original ). 



Fig. 34.— Gallery of Gnathotrichus materiarius in pine (adapted from an unpublished drawing by Prof. 



A.D.Hopkins.) 



borers (Hypothenemus),is found in the Eastern United States and is a 

 rare insect. 



G. retusus Lee. is Californian. All the species live in pine trees. 



