THE ELM-LEAF BEETLE IN NEW YOEK STATE 



19 



columba Linn. This insect is a magnificent four-winged fly about 

 2 inches long, with a wing spread of 2| inches, and a prominent 

 horn at the extremity of the abdomen, hence the common name 

 of horn-tail. It may be recognized by its cylindrical dark brown 

 abdomen with yellow markings as represented in figure 5. 



Fig. 5. Tremex columba : a, larva showing the Thalessa larva fastened to its side ; 6, head of 

 larva; c, pupa of female; d, male pupa; e, adult female — all slightly enlarged 



The female deposits her eggs in the trunks of sickly trees, 

 where its larvae run large cylindrical burrows. Many elms in 

 both Albany and Troy show numerous holes caused by this 

 insect. This borer has a deadly parasite in the lunate long sting, 

 Thalessa lunator Fabr, This beneficial insect is of great aid in 

 keeping the Tremex under control. In the trunk of one smal) 

 elm I found the remains of 13 ovipositors. In their efforts to 

 reach the numerous borers in the tree, the females had driven 

 their long ovipositors so far into the wood that they were unable 

 to withdraw them. 



Another insect which infests debilitated elms is known as the 

 elm borer, Saperda tridentata Olivier, The larvae of this beetle 

 run their burrows under the bark and in the sap wood of the 



