334 BOARD OF AGRICULTURE. [Pub. Doc. 



It is certain that many birds prefer smooth-skinned cater- 

 pillars. Many species have not been observed to eat hairy 

 caterpillars at all, while i;t is safe to say that most land birds 

 feed readily upon smocfth-skinned caterpillars. Take, for 

 example, the larvie of the canker-worm moths, Paleacrita 

 vernata and Anisopteryx pometaria. Nearly all species of 

 birds in eastern Massachusetts, from the titmouse to the 

 crow, have been observed to feed upon these larvse, and 

 when these are abundant most birds seem to prefer them to 

 the hairy caterpillars. The tent caterpillars, hatching as 

 they do very early in the season, form when small a staple 

 food for a great number of birds. Later, as the canker 

 worms appear and the tent caterpillars grow larger and pre- 

 sumably more disagreeable to some birds, they are neglected 

 to some degree, while most birds feed on the canker worms. 

 When the canker worms disappear many birds again resume 

 feeding on hairy caterpillars. The presence of a quantity 

 of smooth-skinned caterpillars, therefore, indirectly benefits 

 the hairy caterpillars. 



Every one who has studied carefully the life history of 

 moths has been struck with the great mortality among the 

 young larvae. In a study of the natural increase of the 

 gypsy moth it was found that where a single egg-cluster 

 hatched isolated from its kind most of the caterpillars dis- 

 appeared while they were quite small ; in some cases the 

 entire brood was destroyed. 



It is well known that the gypsy moth in Massachusetts has 

 few effective natural enemies except the birds. Birds fre- 

 quently have been observed feeding upon the young cater- 

 pillars, and careful observation indicates that many of them 

 are destroyed by birds before they are half grown. Two 

 instances have been reported where small but flourishing 

 colonies of gypsy caterpillars appear to have been exter- 

 minated by birds. Limited outbreaks of the brown-tail 

 moth that have Ijeen watched have been so reduced that at 

 the end of the season few or none could be found. Just 

 what proportion of this destruction is due to the parasites 

 and other enemies of the l)rown-tail moth it is difficult to 

 determine, but the observers are agreed that most of it is 

 due to birds. In some cases the webs of the tent caterpillar 



