8 HALF HOURS WITH INSECTS. [rACKAKD. 



"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 j'.oung 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 huxe averaged less 

 than five or six hundred lice upon each, and there were full}' 

 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 da^'s the whole were exterminated." 



This maj^ 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. Mr. Walsh has, however, discovered that in an 

 American species of gall fly, the spring brood consists of 



8 



