Lake Maxinkuckee, Physical and Biological Survey 11 



1. They destroy multitudes of insect adults and larvae that 

 would otherwise serve as fish food ; they are voracious feeders and 

 they keep at it all their lives. 



2. The nymphs of the larger dragon-flies are strong and agile 

 enough to catch and eat the helpless fry of many of the larger 

 fishes. They greatly prefer insect larvae but will kill the fish 

 rather than go hungry. 



3. On the other hand, many of the insects destroyed are ob- 

 noxious to man. This is especially true of the mosquitoes, gnats, 

 etc., which form the dragon-flies' favorite food. 



4. The dragon-flies themselves, both adults and larvae, are 

 eaten by the fish. The young nymphs when first hatched are 

 nearly as good fish-food as insect larvae, and are easily overpowered 

 by the small .fish which frequent the shallow water where they live. 

 As the nymphs grow larger they become too wary and too power- 

 ful for these small fishes. At the same time they keep coming 

 closer and closer to the shore so that the larger fish do not get a 

 chance to capture them. This explains why so few nymphs were 

 found in the fishes' food during July and August. During the 

 winter and in the early spring, when other food is scarce, these 

 dragon-fly larvae must share with the minnows in supplying food 

 for the larger fish. 



That the adult dragon-flies are eaten by the larger fish is a 

 matter of both direct observation and inference. Repeatedly in 

 the effort to capture some of the more wary dragon-flies a speci- 

 men would be knocked helpless into the water by a blow from the 

 net. Often on these occasions before it could be picked up there 

 would come a swirl in the water and it would disappear down some 

 fish's throat. It was difficult, of course, to identify the fish with 

 certainty, but Libellula pulchella and L. luctuosa were eaten this 

 way on several occasions by Large-mouthed Black Bass, while Celi- 

 themis eponina was taken by the Redeye. Several of the smaller 

 damsel-flies were taken by smaller fish. Reliable anglers also testify 

 that they have seen fish following a pair of dragon-flies, like Celi- 

 themis eponina, which fly about close to the surface over the deep 

 water, the female repeatedly dipping her abdomen beneath the 

 water to deposit her eggs, and that the fish often jump for the 

 dragon-flies. 



Again, dragon-flies are constantly getting into the water, par- 

 ticularly during a high wind and after they have finished deposit- 

 ing their eggs. A careful watch was kept for such individuals 

 every day, but in only one instance during the entire summer was 

 a dragon-fly observed floating on the water. Even this one was. 



