146 
place with an insect which was not a native, but which was imported. 
In the second place the insect preying upon it was also imported, and 
found as the only familiar form upon which it has been used to feed 
just this one species. In bringing over the Yedalia its natural checks 
were not brought with it, and in liberating it in the orange groves of 
California it was given an advantage that it could never have possessed 
in its own country. There may be a few of our insects in a somewhat 
similar position, and possibly some one of us may yet be as successful 
as Dr. Riley was in reference to some other permanently injurious spe- 
cies. It may even be that parasites which in their native home are 
not able to control or exterminate the species upon which they prey 
may, when introduced into this country, have such an advantage that 
they will accomplish more than they could in their native home. I say 
this may be so, but I do not anticipate it in many cases. Insects are 
very slow to change their habits. Just as it is rare for an American 
parasite to attack an imported insect in any numbers, just so rarely 
will we be able to induce a European or other foreign parasite to 
attack the American insects. We have a field here which is compara- 
tively new, and of which we know very little, but it is not that partic- 
ular field that it is my intention to enter. The propositions that I do 
make, and that I am ready to defend are: Among our native insects 
parasites act merely as a check to excessive increase. Excessive increase 
means more than the natural food of the insect is able to support, and 
does not mean excessive increase in the sense of the farmer. An 
insect that is, under natural conditions, abundant each year must be 
dealt with without any regard to parasites or natural enemies. Other 
than I have just suggested, parasites and predaceous insects have 
absolutely no economic value. 
The paper was discussed by several members. 
The following paper was next read : 
INSECT FOES OF AMERICAN CEREAL GRAINS, WITH MEASURES 
FOR THEIR PREVENTION OR DESTRUCTION. 
By F. M. Webster, Wooster, Ohio. 
The three principal cereal grains of America north of Mexico, viz, 
maize, wheat, and oats, cover an approximate area of from 140,000,000 
to 150,000,000 acres. In other words a the natural flora over this vast ter- 
ritory, comprising a great variety of species, has been largely extermi- 
nated, and, instead, but three have been substituted, all of which ar e 
annuals with a capacity for reproducing each year from twenty to two 
thousand fold. As nature is said to abhor a vacuum, so does she resent 
a monopoly, except it be in cases where but few species can exist, and 
the increase of the individuals of these are ultimately restricted by 
