12 



tripiinrfaf a, which was also i-eared from elm-trees infested by iil- 

 micohi. No experiments wei'e tried with other species of elm. 



^fATlIRAL ENEMIES. 



As fi-iay be seen from the foregoing, this species is its own 

 greatest enemy. No egg parasites have been found, though 

 such may confidently be looked for in the future. That the 

 eggs are to some extent destroyed by birds, appears probable, 

 though none were observed in the act. Nuthatches were pres- 

 ent in the trees, both in those infested and in those free from 

 the pest, and the frequent occuri-ence of twigs with the bark 

 pushed upward and outward at the point where the egg is 

 usually placed, as is shown in Plate II., upper figure, suggests 

 clearly that some feathered enemy had pushed its beak beneath. 

 As this lifting of the bark was noticed only on the side of the 

 longitudinal slit where the egg is usually placed, it is fair to 

 presume that either the egg or young larva had been removed. 



GENERAL EFFECT ON ELM-TREES. 



The production of bunches of short twigs which are annu- 

 ally killed and replaced by others, these suffering in turn in the 

 same manner, has been already described, and the inevitable 

 effect on the general appearance of the trees will be clear to 

 any one at all familiar with the growth of young elms. They 

 gradually assume a scraggy, stunted, and misshapen appear- 

 ance, with the foliage inclined to grow in tufts about the larger 

 limbs, the latter throwing up an unusually large number of wa- 

 ter-shoots, which. being killed down each year, add to the un- 

 sightly appearance of the tree. The limbs may increase in size 

 but not in length, as each year's growth is killed back the 

 same year. Sometimes the larviB working in spring pass l)e- 

 yond into lateral twigs which had escaped attack and cause 

 their death. I have found lateral twigs and fresh growths 

 withering and dying from this cause as late as the latter part 

 of May. Larger trees do not show the injury as much as smaller 

 ones, but even the former will lack the broad, wide-spreading 

 growth so much admired in the elm. Not all trees standing in 



