Forest Protection 177 



which they can attack living trees. The weakened con- 

 dition of the trees girdled for trap trees attracts many 

 and the logging of these trap trees destroys them. Other 

 methods are too expensive to be practical. 



Elm-leaf beetle 



The elm-leaf beetle (Galerucella luteola) is one of the 

 most familiar enemies of the elm tree throughout its 

 range. It has destroyed thousands of shade and lawn 

 trees, and, when numerous, frequently spreads to the 

 woodlot and forest. It is evidenced by the skeletonized 

 brown leaves in midsummer and the falling caterpillars. 



The beetle is \ inch long, orange and black when young 

 and a dull bronze-green when he has wintered over. 

 The caterpillar is ^ inch long when young, hairy and 

 almost black, but grows to \ inch in length and changes 

 to yellow and black. The pupa is a bright orange-yellow 

 and | inch long. The eggs are an orange-yellow, 3-26 

 of them being in irregular rows on the underside of the 

 leaves. 



The elm-leaf beetles winter over in attics, sheds and 

 other protected places. They fly to the trees with the 

 coming of the leaves, eating irregular holes in the foliage 

 and feeding for some time before they begin to lay. They 

 lay a few eggs daily for a month or six weeks and sometimes 

 total as many as 650. The eggs hatch in less than a week 

 and the grubs appear about the middle of June. These 

 larvae feed on the under surfaces of the leaves and skele- 

 tonize them. They are full grown in 15-20 days, and wan- 

 der down the trunk to pupate in some crack or other 

 slight shelter. This is accomplished in about seven days. 



