ELM LEAF BEETLE IN NEW YORK STATE 



19 



crawl on the foot of a bird and thus be transported from one 

 tree to another. Other insects may also to a certain extent 

 transport them and' some, falling with the leaves, might sue- 

 cessfulh' make their way up another tree; the chances, however, 

 are against the latter method. 



SECONDARY ATTACKS BY IXSECTS 



It is well known to students of nature that an enfeebled tree 

 apparently invites attack by certain insects which seem to find 



Fig. 1 Tremex columba: a, larva showing the Thalessa larva fastened to its side; b, head of 

 larva; c, pupa of female; d, male pupa; e, adult female; all slightly enlarged. (After Riley, 

 Insect life, v. 1, fig. 39) 



in the unhealthy tissues conditions peculiarly fitted for their 

 development. The ravages of the elm leaf beetle have encour- 

 aged certain of these pests to a marked degree. One of the 

 most common and injurious is known as the pigeon Tremex, 

 Tremex c o 1 u m b a 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 from 

 which it gets tlie common name of horn tail. It may be recog- 



