5. DRAGONFLIES AND FISH CULTURE 
The nymphs of Odonata are strictly carnivorous. This means that, 
directly or indirectly, they are competitors with the fishes for the 
common food supply of the water. They belong to the consuming 
class. They are not primary producers of flesh. They are themselves 
eaten by fishes, to be sure, and under certain conditions of abundance 
they may be important in the food supply*; but their production 
involves an additional turnover of the flesh that herbivores create, 
and from the economic point of view, this is wasteful. Whether the 
waste is justifiable in practice remains to be demonstrated. 
That the larger dragonfly nymphs habitually eat very young fishes 
is well known to fish culturists. The following letter communicated by 
Professor Cockerell (Ent. News, 30: 719) furnishes good evidence. 
It was written by Mr. Frank Springer from the Abbott Ranch, Rito 
de los Frijoles, N. Mex., and concerns the nymphs of the Western 
Biddy, Cordulegaster dorsalis: 
I am sending you some beasties, that I should like to know more about. 
They are highly predacious devils, and I first discovered them in the act of seizing 
some of a lot of young trout which I was placing in the brook here. The bug lies 
buried in mud or sand, and in shallow parts of the stream where the current is 
not very swift, with only his eyes projecting. When a little fish (about an inch 
long) comes wiggling along close enough over the bug, he snaps, projecting his 
formidable mandibles and the shovel-like part below them for quite a distance 
to the front, and catches the fish by his wiggling tail. By simulating the wiggling 
motion of a fish with a knife blade, I could induce the bug to snap at it, and 
thus saw the motion several times. .... I found the creatures quite numerous 
in the shallow, quieter waters where I was planting the young fry, and apparently 
they constitute a rather serious menace to the stocking of the stream, as they 
infest the shallow places, while the deeper water is dangerous on account of the 
older fish. I found that the trout eat these bugs to some extent as in several 
instances they were contained in the stomach; and they are readily taken when 
offered as bait. 
We have as yet no measure of the losses thus occasioned, but where 
large dragonfly nymphs become abundant these are doubtless con- 
siderable.* 
* Wilson (’20) has made the best possible argument for their economic value. 
* Here are some extemporaneous remarks by the Fish Warden of Kansas, 
quoted in the Trans. Amer. Fisheries Soc., 56: 62, 1926: 
“The dragonfly has an apparatus that he shoots out ahead of his body, like 
a@ snapping turtle; he grabs the young fish right in the stomach, and the result 
is that the fish dies. We have had large numbers of fry killed by the larvae of 
dragonflies, which, as you know, attain a considerable size in our country. The 
dragonfly may be classed among the vermin of the ponds, and he certainly 
wrecks havoc among the fry when there is nothing to protect them.” 
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