Allen on Insectivorous Birds. 
2 3 
I have compared notes with other bird-lovers who share the same 
misgiving, based on their own casual study of the subject. But 
whatever the final outcome of such investigation, sentiment should 
of course give way to truth. Whether insectivorous birds, con- 
sidered from the utilitarian side, are beneficial in their relation to 
agriculture, or positively (at least in many cases) injurious, or 
merely hold a neutral place, it is far too early yet to decide, for 
thorough investigation of the subject can be considered as having 
merely begun. The fact that they destroy large numbers of nox- 
ious insects is established beyond question ; whether they do 
not at the same time devour so large a proportion of beneficial 
ones as to fully or more than offset the good they accomplish 
in the destruction of the former may be considered as an open 
question, which years of careful observation can alone decide. 
From investigations now in progress, notably in this cpuntry at 
the hands of Professor S. A. Forbes of Normal, Illinois, it is to be 
hoped that the data for an intelligent judgment in the matter will 
be soon reached. To Professor Forbes is due the credit of not 
only first directing attention to the subject, but of first instituting 
systematic research respecting the relation of birds to predaceous 
and parasitic insects. In addition to his own observations he has 
published a translation * of M. Edouard Perris’s memoir on this 
subject, published in 1873 in the “-Bulletin mensuel de la Societe 
d’Acclimatation.” j* M. Perris, after many years of careful ob- 
servation, expressed himself as “ convinced that the current ideas 
respecting the utility of birds are prompted by impulse rather than 
reflection,” and, he adds, u I believe that, if more attention had been 
paid to the rble played by insectivorous birds and to the mode of life 
of the insects which injure us, very different conclusions would 
have been reached.” After reviewing the subject at length, and 
presenting in detail his long array of facts, he formulates his de- 
ductions, calling attention to the fact that birds are scattered here 
and there in pairs 1,1 while insects invade en masse the trees which 
they attack, the products of the soil of which they are the ene- 
mies” ; that while birds destroy enormous numbers of insects, 
these insects are in great part innoxious, while some are eminent- 
ly useful. u The species really noxious are so few compared 
with the whole mass, that birds are really of little service. They 
* American Entomologist, new series, Vol. I, 1880, pp. 69-72, 96-100. 
t Republished here from the* Mem. de la Soc. roy. des Sciences de Lieg§. 
