BIRDS, CATERPILLARS, AND PLANT LICE. 111 
“ CHAPTER III. 
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. J 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 
l Institut Horticole de Fromont, 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 
