84 PRELIMINARY NOTES ON THE ODONATA. 
of disturbance several times and succeeded in binding the dragon-fly 
fast before becoming frightened at the observer and retreating. It 
was not seen to bite and the insect remained active, until, after waiting 
some fifteen minutes for further developments, 1t was removed to the 
cyanide bottle. 
In his “Dragon-flies of the Mississippi Valley” Wilson states that 
he found Gomphus spicatus feeding largely upon damsel-flies, notably 
Enallagma and Ischnura. Gomphus villosipes was seen catching and 
eating Leucorhinia and Sympetrum. 
Regarding the nymphs, not so much is known in this particular: 
Needham shows that a few of the larger species are eaten by the trout 
and it is more than probable that the damsel-flies are destroyed in 
great numbers. Many, if not all, species are cannibals. The larvae of 
the water beetles (Dytiscidae, Hydrophilidae, etc.) prey upon crayfish, 
tadpoles and probably on nymphs. 
Economic Importance of the Odonata. 
It has been the custom to consider the Odonata of no practical 1m- 
portance. These insects have never annoyed man and seemingly have 
not aided him in combating pests which destroyed his crops or harmed 
domesticated animals. Dr. J]. B. Smith repeatedly affirmed his faith in 
the neutrality of the group and other workers have quite universally 
taken the same stand. 
It is certainly true that if dragon-flies are influential for better or 
worse in man’s welfare, the part they play is not obvious. However, 
we cannot but refer to the day, a decade or two ago, when the mos- 
quito, the stable-fly, the house fly and the sand-fly were but annoy- 
ances, and though the dragon-fly seems incapable of directly taking a 
place similar to that of these insect carriers of disease, it may be shown 
later to be of value in control conditions. 
The most frequent suggestion of this kind is that dragon-flies 
reduce the number of mosquitoes. Applied to the adults the objection 
is made that mosquitoes are active at night and that the dragon-flies are 
on the wing during the day only. While this is generally true there 
are several species of our larger and more numerous dragon-flies 
( Aeshna, etc.) that are very active from sundown until dark, hawking 
about quite close to the earth and frequenting not only the swamps 
and open woodlands but even venturing in numbers about the lawns in 
town and cities. Dr. Walker describes the occurrence of Neurocordulia 
yamaskanensts on Georgian Bay, Ont., and states that no imagos could 
be found on the wing during the day but that numerous specimens were 
