8 
HALF HOUKS WITH INSECTS. [Packard. 
“This species commences to appear as soon as the leaves 
begin to put forth in the spring. * * * They bring forth 
their young alive during the continuance of warm weather. 
These huddle around their parents upon the under surface of 
the leaves as closely as they can crowd themselves; indeed 
they often are found two deep, a portion of the colony 
standing upon the backs of the others, requiring only suffi¬ 
cient space between them to insert their beaks into the leaves 
to suck their juices. The numbers which thus make out to 
stow themselves within a narrow compass are almost incred¬ 
ible. Upon the under surface of a small leaf three-fourths 
,of an inch long and half an inch wide I have counted upon 
one side only of the midvein one hundred and ninety of these 
lice. Yet this leaf was not more densely covered than many 
others. The surface of a small leaf but an inch long would 
therefore furnish ample space to accommodate a thousand of 
these insects. * * * Among the cherry trees alluded to 
above was a row of seven young ones which had attained a 
height of about ten feet. By counting the number of leaves 
upon some of the limbs and the number of limbs upon the 
tree, I find a small cherry tree of the size above stated is 
clothed with about seventeen thousand leaves. And at the 
time alluded to these leaves could not have averaged less 
than five or six hundred lice upon each, and there were fully 
a third more occupying the stems and the tips of the twigs. 
Each of these small trees was therefore stocked with at least 
twelve millions of these creatures. And yet so vigilant, so 
sharp sighted and voracious were their enemies that at the 
end of a few days the whole were exterminated.” 
This may help us to explain why males of certain species 
of gall flies have never been discovered, though a German 
entomologist has examined over two thousand females of one 
species, and not a foreign element occurred in this nation of 
Amazons. Mrl Walsh has, however, discovered that in an 
American species of gall fly, the spring brood consists of 
8 
