BIRDS, CATEBPILLABS, AND PLANT LICE. 147 



in a tree near the edge of the colony, sang for a few minutes, then flew 

 to the sprouts that are infested, then to the ground. He scratched in 

 the leaves, and I saw him take seven pupa3 from the leaves, and two 

 larvi« that were crawling on the ground. There was a pair of Great- 

 crested Flycatchers coming and going all day. They took a great many 

 male moths, and I saw them take live female moths from the tree 

 trunks. A Rol^in jjerched in the tops of the oak trees, picked off four- 

 teen of the pupas from the branches, and ate them. A Yellow-bellied 

 Sapsucker came, and I saw it eat two pup:i3. It remained at least 

 half an hour more, but I could not see what it was doing. A Yellow- 

 billed Cuckoo ate ten larvae in a few miiuites. 



Thousands of these insects are undoubtedly eaten by birds, 

 for every one that they are seen to eat ; but, it may be asked, 

 if the birds are effective enemies of these introduced gipsy 

 larvt^, why have they not kept down tlie increase of tliese 

 insects'? To this it must be answered that we have not birds 

 enough, nor are there likely ever to be enough, to do away 

 with these pests entirely, unless birds learn to eat the eggs. 

 Other natural enemies must also help in this work, if w^e are 

 to see an end of the moth plague ; but there is little that we 

 can do to protect the insect enemies of the moth or to insure 

 their multiplication, while we can protect and feed the birds, 

 and so secure an increase in their numbers. In so far as 

 we are able to take measures that will result in increasing 

 the numbers of certain birds, just so far shall w^e be able to 

 prevent the increase of destructive insects. As time goes 

 on, it is prol)able that birds will liecome more and more effi- 

 cient as enemies of the gipsy moth and the brown-tail moth, 

 as they learn better how to manage them. It seemed appar- 

 ent that they had not learned to eat the eggs of the gipsy 

 moth up to 1896, when I last studied that subject, but now 

 (1912) Messrs. AVilfrid Wheeler and Wilson II. Fay and 

 Drs. H. B. Bigelow and A. W. Tuttle assert that Downy 

 Woodpeckers and Chickadees destroy the eggs in some 

 localities. As the gipsy moth spends more than half the 

 vear in the eoo- this is its most vulnerable ])()int. If 

 Jays, Creepers, Nuthatches, Woodpeckers, and other birds 

 could learn to eat these eggs, as European birds are said to 

 do, they would then have an increased food supply the year 

 round. Xaturallv thev would increase in numbers, and thus 



