18 
sayanus),and the common perch (Perca flavescens). The latter is 
anabundant species in the small northeastern lakes of the state. 
Belostoma, Ranatra, Notonecta, and the like, according to 
Mrs. Aaron (Lamborn, ’90, p. 50), prey on young nymphs, and 
she also mentions a small red mite and a minute dipteron as 
parasitic on the eggs of Odonata. Mr. Needham (798) has 
recorded the finding of numbers of nymphs in the stomachs of 
herons, and he once found the intestine of a nymph parasitized 
by very large Gregarinide fully 1 mm. long. 
Emerging imagos while limp and pale are the easy prey of 
even their weakest enemies, and great decimation takes place 
among them at this time. Ants, spiders, robber-flies, frogs, and 
birds eat many of them. 
The full-fledged dragon-flies devour the small insect life of 
the air in vast quantities, especially gnats and mosquitoes, most 
of which probably developed in the waters previously inhabited 
by the dragon-fly nymphs. These seem to make little or no 
attack upon the larval stage of the gnats and mosquitoes, as if 
reserving them for their imago life. Dr. Lamborn, by offers of 
prizes, started an investigation to determine the practicability 
of artificially utilizing dragon-flies for the destruction of mos- 
quitoes and flies; but the evidence published (Lamborn ’90) 
indicates that these pests may be dealt with more effectively 
by direct measures, since the the attack of dragon-flies could 
not easily be controlled and directed, although in their own way 
and time they doubtless reduce the numbers of the pests very 
considerably. 
Mature dragon-flies do not usually suffer seriously from 
natural enemies. They are frequently found infested by small 
~ed mites. Some birds, such as the king-bird, possess sufficient 
~tness to capture them as regular articles of their food. It 
to be the weaker forms, such as Agrion, that suffer thus 
»xtensively (Needham ’98). The females while oviposit- 
netimes captured by fishes. 
COLLECTING AND REARING. 
~deration of the statements and suggestions 
