LITTLE AIR POLICEMEN 245 
and the cycle of growth is thus kept up appar¬ 
ently without a break in the ranks of the air po¬ 
lice force. They are indefatigable in the pursuit 
of their duties, and dart hither and yon, altering 
their direction with the most surprising sudden¬ 
ness, and never by any chance failing to seize 
upon their prey. Possibly gnats and midges 
are seized with the jaws, but larger specimens are 
undoubtedly pinioned by means of the curious 
legs, which are so adeptly curved and turned for 
grasping. Always the victim is devoured during 
flight, and so rapidly is the whole performance 
executed that it is impossible to more than guess 
at the details. Flies form the bulk of the diet, 
but small butterflies and moths are frequently 
taken, and on occasion a wasp has been seen to 
disappear before the dragon-fly’s lightning 
charge. Large dragon-flies are said to devour 
smaller ones, and indeed will even grasp vora¬ 
ciously at their own bodies when offered them. 
They have enormous and indeed apparently en¬ 
tirely unappeasable appetites. One authority 
affirms that he fed a certain large specimen forty 
house flies inside of two hours. 
“ Some two thousand species of dragon-flies 
are known, three hundred of these being found in 
America, but never all of them in any one local¬ 
ity. States differ in regard to the number. For 
example, something over one hundred may be 
