BIRDS, CATERPILLARS, AND PLANT LICE. Ill 



CHAPTER ffl. 



BIRDS AS DESTROYERS OF HAIRY CATERPILLARS AND 

 PLANT LICE. 



Certain caterpillars are provided with defences which are 

 supposed to give them immunity from the attacks of birds. 

 It is now believed quite generally, by both ornithologists 

 and entomologists, that such protective devices are effective 

 against nearly all birds. I have learned, however, by both 

 observation and dissection, that in many cases such protection 

 does not protect. American writers seem to have accepted 

 the evidence of Europeans on this subject without having 

 taken the trouble to investigate the matter fully by observa- 

 tion at home. Among the earliest of this European "evi- 

 dence" now at hand is a paper by a writer in the Annales de 

 1'Institut Horticole de Fremont, Vol. 5, p. 311, published 

 in Paris in 1833. In discussing the opinion promulgated by 

 the Natural History Society of Gorlitz, that the diminution 

 of fruits is on account of the diminution of birds, he places 

 the caterpillar of the gipsy moth at the head of the list of 

 injurious caterpillars, saying that "above all it is very essen- 

 tial that it be destroyed." He says further, that, as these 

 caterpillars are armed with long hairs, the birds guard well 

 against bringing them to their young ; and that in twenty 

 years of observation he has never seen a bird take one to its 

 young. He also states that these insects when in the chrysa- 

 lis are not sought by birds. 



A more recent source of this widespread belief is indicated 

 by Dr. Packard, who, writing in 1870, notices some inter- 

 esting facts brought out by Mr. J. J. Wier of the London 

 Entomological Society, in the. following words : - 



He finds, by caging up birds whose food is of a mixed character 

 (purely insect-eating birds could not be kept alive in confinement), 

 that all hairy caterpillars were uniformly uneaten. Such caterpillars 

 are the "yellow bears" (Arctia and Spilosoma) and the salt-marsh 



