1909] JOHNSON — LOCAL ECOLOGICAL STUDIES 5 
THE IMPORTANCE OF LOCAL ECOLOGICAL STUDIES TO 
ENTOMOLOGY .* 
BY CHARLES W. JOHNSON, BOSTON, MASS. 
In the study of geographical distribution, all realize in a general way the great 
changes which have taken place over the entire country since America was settled 
by white men. ‘The destruction of the forests by the axe and fire, the clearing and 
cultivating of the land, the diminution and pollution of the streams, the draining 
and filling of swamps, the construction of reservoirs and dams and extensive mining 
operations, all tend toward changing physical conditions governing the existence and 
distribution of the flora and fauna. 
How frequently we hear complaints of the inadequate data kept by the early 
naturalist, of species now practically extinct. Here we might ask these questions: 
Are we keeping requisite data for future investigators? Are we taking into account 
the local changes which have taken place, and are continually taking place, and 
their effect upon the fauna and flora? ‘These changing conditions, which have so | 
long appealed to the mammalogist, the ornithologist and botanist, have either been 
ignored, or only touched upon lightly by entomologists. It is not often intentional 
on their part, for entomologists have a great deal todo. Then too there are so many 
insects, and species are often so widely distributed, that when they become scarce in 
one section they can so readily be obtained from another, that local conditions affecting 
certain species are easily overlooked. 
In entomology there are other factors besides changes in physical conditions to 
consider, among which are the introduction of injurious insects through com- 
merce and otherwise, followed by the introduction of their parasites to aid in keeping 
them in check. One naturally asks what will be the effect of the introduced 
parasites on the indigenous species. When these parasites are established, will they 
infest the native species and perhaps locally exterminate them? ‘This seems to be 
the solution of the extermination of Pontia oleracea in many parts of New England 
after the introduction of A panteles glomeratus, the parasite of the European cabbage 
butterfly (Pontia rapae). Another factor is the extensive cultivation of trees and 
plants far beyond their natural limits, thus enabling the insects feeding upon such 
Presidential address at the annual meeting of the Cambridge Entomological Club, January 19, 
1909. 
