DRAGONFLIES AND DAMSELFLIES IN PONDFISH CULTURE. 219 
of egg layers around the ponds, and thus affects the supply of fish food. Would it not 
be better to get rid of the dragonflies and allow these other insects to breed without 
hindrance? At first sight it seems as if the answer must be in the affirmative, but a 
little reflection makes it appear differently. If the nymphs of the dragonflies make as 
good food for the larger fish as the larve of these other insects make for the smaller 
fish, then it is as important for the dragonfly imago to survive and lay its eggs as for 
any of these other species. Larger fish will not thrive well on food suitable for fry, and 
if something is not provided for them they will eat one another. Bass, perch, sunfish, 
buffalofish, catfish, and crappies are well satisfied with the larvee of mosquitoes, gnats, 
and flies for a while and will thrive on them. But the time soon comes when this food 
no longer satisfies them and they demand something larger. (See p. 225.) 
The period during which the smaller larve prove sufficient varies considerably 
with the kind of fish, but they will all thrive better if the larger food is present in the 
pond, so that they can change to it gradually whenever they choose. It is definitely shown 
in another place (p. 228) that when the young fish reaches a length of about 25 mm. it 
begins to eat odonate nymphs. It takes some fish much longer to reach this length 
than it does others, and even in the same brood some fish grow faster than others. 
Hence the larger food must be present all the time to accommodate the different rates 
of growth. 
Furthermore, actual observation shows that the presence of odonate nymphs and 
imagos does not necessarily diminish the supply of smaller fish food. The number of 
dragonflies has steadily increased around the Fairport ponds during the last five years, 
but at the same time the number of other insect larve and Entomostraca has increased 
apparently as much, so that conditions suitable for fish culture were never better than 
at the present time. 
Again, whatever the kinds of fish, they must be successfully carried through the 
winter, and there must be enough food in the pond to keep them in good condition. 
By the time the pond freezes over most of the young fish have become large enough to 
demand good-sized food, and the larger they grow the more insistent will this demand 
become. Moreover, some of the animals which are included among this smaller food, 
such as the Entomostraca and several of the insect larve, are much less numerous 
during the winter. At other times of the year odonate nymphs furnish acceptable food 
for fish, and there is every reason to believe that they continue to do this through the 
winter, which is just the season when it is most needed. Only a few fish have been 
examined at Fairport during the winter, but the limited observations that have been 
made seem to support this idea. Twelve largemouth black bass, Micropterus salmoides, 
averaging 130 mm. in length and 18 bluegills, Lepomis incisor, averaging 107 mm. in 
length, from pond 1D, 19 of the same bass, 44 mm. in length, from pond 2D, and 12 
bass, 185 mm. in length, from pond 3D, were examined February 15-17, 1917. Of 
these 61 fish, the stomachs of 46 were found to be either entirely empty or so near it 
that the débris present was indistinguishable. The food of four of the remaining 
fish, two bass and two bluegills, consisted entirely of odonate nymphs, and they were 
probably identified in the débris of the stomachs of two other bluegills. This record 
is too meager to possess much value beside the ample proof elsewhere presented (p. 225), 
but it does show that the fish will eat nymphs during the winter, as suggested. 
As a third consideration, although nature’s equilibrium must be made subservient 
to man’s designs and control in intensive pondfish culture, it is still true that, other 
