EFFECT ON SPAN-WORMS. 109 



"The above species seem, in the ordering of nature, to have been as- 

 signed to us for protection from an undue multiplication of a large num- 

 ber of hairy caterpillars of iojurious habits. * * * One of them, the 

 Yellow-billed Cuckoo, is known to shave off the hairs of the Orgyia 

 leucostigma caterpillar before swallowing it. The following account of 

 the operation is from Dr. LeBaron, former State Entomologist of Illinois: 

 4 My attention was attracted to a Cuckoo regaling himself upon these 

 caterpillars, which were infesting in considerable numbers a larch grow- 

 ing near the house. My curiosity was excited by seeing a little cloud 

 of hair floating down upon the air from the place where the bird was 

 standing. Upon, approaching a little nearer I could see that he seized 

 the worm by one extremity, and drawing it gradually into his mouth, 

 shaved off as he did so, with the sharp edge of his bill, the hairy coating 

 of the caterpillar and scattered it upon the wind.' " (Second Report on 

 the Injurious and other Insects of the State of New York, by J. A. 

 Lintner, Albany, 1885.) 



Relation to the canker-worm and other span-worms. — As early as 1874 Dr. 

 John L. LeConte, of Philadelphia, Pa., published* the following in re- 

 gard to the disappearance of the span-worm in that city and its replace- 

 ment by another species : 



u In Philadelphia, and probably in other cities, the Geometride (Un- 

 nomos snbsignaria), which was very injurious to the shade trees growing 

 in the streets, has been exterminated by the European Sparrows, intro- 

 duced for that purpose. With the disappearance of the Geometride a 

 Noctuide, Orgyia leucostigma, commenced to increase, and has now in 

 some streets become almost as great a nuisance as the Unnomos had 

 been. The larvae of the Orgyia, whether protected by some disagree- 

 able odor, or more probably by the stiff hairs with which they are cov- 

 ered, are not eaten by the Sparrows, and therefore increase without 

 molestation.' 7 



We must demur somewhat to the above statement of Dr. LeConte 

 that the English Sparrow exterminated Unnomos in Philadelphia. That 

 the Sparrows contributed their mite to this end there is no doubt, but 

 other span-worms have disappeared in the same way from towns and 

 villages where there were no Sparrow3, and it is now known that such 

 disappearances are of more or less regular occurrence, and may be due 

 to various causes, such as the multiplication of the insect parasites of 

 the worms, the prevalence of disease, or even in part to the very fact 

 of the extreme abundance of the worms themselves. 



In New England the span-worm which defoliated the elms of the cities 

 and the apple orchards of the country was the canker-worm (Paleacrita 

 vernata), and from different parts of New England unimpeachable tes- 

 timony has come as to the good work done by the Sparrow in feeding 

 on this worm. We ourselves have seen thousands of these worms car- 



* Proc. A. A. A, S„ Vol, XXIII, p. 44, 



