294 



BEES AND WASPS 



One form is particularly interesting, Tremex columha, or 

 horn tail or pigeon tremex. It has a rather peculiar shape 

 both in the larval and adult stages. The adult is an inch 

 or more in length and with a prominent ovipositor which 

 extends back about one-half inch from the back of the 

 abdomen; both larva? and insects are cylindrical, the result 

 of the boring habit. These adults appear in summer and 

 deposit eggs on the bark of different kinds of forest trees — 

 sycamore, maple, and others. The larvi^ burrow in, form- 



FiG. 236. — Pear slug: «, adult saw fly, female; b, larva with slime 

 removed; c, same in normal state; d, leaves with larvoe, natural size; 

 «, 6, c, much enlarged. (From Marlatt, Div. Ent., U. S. Dept. Ag.) 



ing tunnels through- the heart wood pretty well down into 

 the tree. Sometimes the trees are extensively perforated. 

 Boring continues in through the tissue of the wood till they 

 get their maturity and then they burrow out through the 

 bark. Pupse are formed in the burrow near to the surface 

 of the tree and the adult works its way out from the cocoon 

 after the pupa is split open. Occasionally the adults will 

 be found with the ovipositor fast in the bark of the tree 

 or in the wood. They burrow in to deposit eggs and seem 



