NATURE’S MEANS OF LIMITING THE NUMBERS OF INSECTS. 281 
flies proceeding from these were let loose in three per con- 
Fig. 72. 
oe of the Apple Scale Insect, 
of determining the presence of the chaleides. Even if the exper- | 
iment should prove ultimately successful, it would be very doubtful 
‘Whether the chalcis marks would be sufficiently numerous to be 
__ detected at the close of the first year, but oe this they would be 
likely to multiply in a rapidly ine creasing ra 
“ About the last of May, 1872, ao is, Pel the intervention of 
- One year from the time of commencing this experiment, Capt. 
eebe examined some of the trees to which the chalcis twigs had 
been attached, and after a careful search thought that he had dis- 
_ covered a few traces of the o opera ations of the chalcides, and sent 
ear ee On the 13th of sul, I visited Galena and, in com- 
otk with Capt. Beebe, submitted one of the- trees, to which the 
greatest number of the twigs had Peen attached, to a thorough- 
examination. 
“The result, if not actually conclusive, was at least extremely 
encouraging, e detected a considerable number of holes in the 
scales, which ations to be identical, invevery respect, with those 
made by the chalcis in question, and in one instance we discovered 
inche of these holes upon the same twig, within a space of four 
inches. 
“In conducting an experiment of sodelicate a nature I am well 
aware that the greatest caution must be exercised to avoid jumping 
to hasty conclusions, and that the observations of a number 
Succeeding years will be necessary before we can arrive at a defi. 
nite conclusion that the spa ent has been followed by a prac- 
tical a: s well as scientific succes 
we concluded with the following remark : Trei absence of the 
Chalcis of the bark louse, in this locality, will furnish an excellent 
Opportunity for testing the practicability of transporting it thither 
