No. 4.] SIIADK-TREK INSIST PROI5LKM. 81 



driven out the native birds. In the farming communities 

 just outside this city damage by the canker worm is now of 

 frequent occurrence. The hilltops to the west, Chesterfield, 

 Huntington and Blandford, for example, are not yet occu- 

 pied by the sparrow. There cuckoos, orioles and warblers 

 nest undisturbed, and there the chickadee, nuthatch and 

 woodpecker ply their trade throughout the year. Although 

 the canker worm breeds in these localities, it is seldom able 

 to develop in numbers sufficient to commit serious harm. 

 Damage by the sparrow along this line is particularly notice- 

 able in the case of insects which are general feeders. Special 

 feeders, insects like the elm-leaf beetle, limited to one or a 

 few food plants, cannot spread beyond a certain area without 

 exhausting their local food supply ; thus they are subject to 

 limitations which eventually confine their activities. On the 

 other hand, general feeders, like the gypsy moth, forest tent 

 caterpillar and web worm, are not restricted to a single or 

 even a few food plants ; hence in their cases man stands in 

 even greater need of the help given by birds and parasites. 

 Add to this the fact that these general feeders are usually 

 hairy, and that hairy caterpillars are seldom eaten by the 

 sparrow, and the damage caused by this bird is seen to be 

 greater than would at first appear. 



So far as Massachusetts is concerned, the greatest damage 

 to shade trees by insects in recent years has been caused by 

 certain imported pests. These insects, accidentally brought 

 to our shores, usually arrive unattended by the parasites 

 which hold them in check in their native environment. 

 Finding America a land of freedom indeed, they commit 

 depredations by the side of which their ravages in the Old 

 World frequently pale into insignificance. 



Perhaps as good an illustration as any of this point is 

 found in the case of the San Jos6 scale (Aspidiotus pernici- 

 osm), which, primarily a fruit-tree insect, is becoming a 

 dangerous enemy of shade trees in many localities. Intro- 

 duced into California in the early seventies, it has spread 

 into nearly every State if not every one in the Union, kill- 

 ing nursery stock, fruit trees and even shade trees of good 

 size. Probably no more deadly orchard insect ever found 



