86 
hairs or spines, which are supposed to be so disagreeable to the taste 
of birds as to grant such insects immunity from attack. In sueh 
research as the writer has been able to make in entomological litera- 
ture the statement frequently has been met with that birds will not 
eat hairy caterpillars. This astonishing error has been repeated time 
after time until it has come to be regarded as a sort of axiom among 
both entomologists and ornithologists. 
Years ago the writer learned by observation that cuckoos, orioles, 
vireos, and titmice were destroying a great many hairy caterpillars. 
When our work on the gipsy moth was begun in Massachusetts in 
1891, the men employed were instructed to watch carefully all enemies 
of the gipsy moth and to note to what extent these enemies affected 
the moths’ increase. Among these men there were at that time eleven 
who were familiar with the common native birds. Reports that certain 
speciesof birds were eating the gipsy caterpillars began to come in freely. 
These reports and their confirmation caused the continuance of careful 
observations during the past nine years. As a result of these observa- 
tions, Supplemented by stomach examinations, we now have much accu- 
rate information as to whatextent our common land birds eat certain hairy 
caterpillars. The observations recorded have been made mainly with 
reference to four species of caterpillars which can bereadilyidentified by 
the observer, all of which are now common in the district infested by 
the gipsy moth in Massachusetts, viz, the gipsy-moth caterpillar 
(Porthetria dispar), the brown-tail caterpillar (Huproctis chrysorrhea), 
the tent caterpillar (Clistocampa americana), and forest tent caterpillar 
(Clisiocampa disstria). Every care has been used to secure the most 
accurate results from these observations. The caterpillars have been 
carefully identified, and the trees or branches infested by them have 
been watched to learn what other species of insects, if any, have been 
present. The observer has even gone so far as to count the number of 
caterpillars upon a branch, watch the branch until it was visited by a 
bird, count the number of caterpillars eaten by the bird in a giventime, 
and then count the number of caterpillars left upon the branch. 
Since this work was begun thirty-eight different observers have made 
reports, and some of these observers have reported their observations 
year after year. Many of these observations have been so carefully 
conducted and so many corroborative reports have been received, one 
after another, from independent observers that there can be no doubt 
as to the accuracy of the conclusions reached. In fact, there is much 
that can be learned by such observations that can not be determined 
by stomach observations alone. One should supplement the other. 
By examining the contents of birds’ stomachs, a great deal of accurate 
information can be gained in regard to the character of their food. 
Such examinations alone, however, should not be entirely depended 
upon, for, owing to the manner in which some birds prepare some kinds 
