12 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 



in front. Female antennae with a long bristle rising from the 

 anterior edge of each joint of the funiculus, and the first and 

 second joint of the club; also with a few long hairs, all curving 

 upwards. 



1906. Felt, E. P. (35). 



Only reference to Hopkins (17). 



1907. Fall, H. C, and Cockerell, T. D. A. (36). 

 Gnathotrichns retusus Lee. Gallinas Canon (Doctor Snow). 



1909. SWAINE, J. M.(4o). 

 References to literature only. 



1910. Hagedorn, M.(42). 

 References only. 



1914. ^Swaine, J. M.(47). 



Swaine brings a short discussion of the habits of Gn. retusus Lee. 

 and sulcatus Lee. In general it can be concluded that these 

 habits are very similar to those of Gn. materiarius Fitch de- 

 scribed by earlier authors. The author says : 

 The adult beetles excavate cylindric tunnels, about the diameter of a small 

 pencil lead, from four to about six inches into the wood. The entrance 

 tunnel, entering usually in the depth of a bark-fissure, passes directly 

 through the bark and into the wood for from one to two inches ; there 

 branching takes place in a somewhat irregular fashion, though all parts 

 of the set of tunnels extend in the same horizontal plane. Usually one long 

 side-tunnel is cut shortly within the bark, parallel to the wood surface. 

 The meal-like boring-dust and excrement are extruded through the entrance 

 hole. Along the inner tunnels above and below, the females cut cup-like 

 niches and deposit an elongate egg in each. The larva which hatches 

 from the egg lengthens the niche in which it finds itself into a short tunnel 

 or larval-cradle, slightly more than its own length when full grown, and 

 transforms therein to the pupal stage, with its head toward the egg- 

 tunnel. The pupa transforms to the adult in the cradle. The chief food 

 of the larva, and an important food of the adult, is a peculiar fungus 

 called Ambrosia, which grows in a dense glistening layer upon the walls 

 of the tunnels and cradles. It penetrates the cut wood-cells and grows 

 for a considerable distance along the vessels, but is entirely saprophytic in 

 its relation to the wood. The walls of the tunnels are stained black for a 

 millimeter or more in thickness. These, small, black, round, branching 

 tunnels in the wood are characteristic of the Timber-beetles or Ambrosia- 

 beetles. 

 The winter is passed by parent adults in the tunnels and cradles, and pupae 

 and larvae of various sizes in the cradles. Apparently work is continued 

 in these tunnels in the spring; and new tunnels are started by the young- 

 adults. A second brood appears and starts fresh tunnels early in August. 



