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PRELIMINARY STUDIES OF N. AMERICAN GOMPHINÆ

Published online by Cambridge University Press:  31 May 2012

James G. Needham
James G. Needham
Affiliation:
Cornell University, Ithaca, N. Y.
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Extract

Examples of the emphasized importance of larval life better than that furnished by the subfamily Gomphinæ of Odonata are few even among insects. The nymphs live under the sediment (mostly organic debris) which falls to the bottom of ponds and streams. They are aquatic burrowers which live at such slight depth that their anal respiratory orifice is never beyond the reach of clean water. This thin stratum, which forms their home and which they only leave to transform, is one of great biologic richness. In it they have found room for development in enormous numbers and necessity for extreme specialization. They are, at least when well-grown, among the more powerful members of its teeming hidden population. The imagoes emerge, flit about under cover for a few days, lay their eggs and die. They emerge largely by daylight and are subject to great decimation of numbers at this time, and are sought later by numerous powerful enemies. The females which live to oviposit lay a very large number of eggs. A female of Gomphus fraternus laid for me in a watch glass of water over 5,000 at one time. The imagoes of the ancient genus Gomphus are regarded as a race of weaklings. Their nymphs, on the contrary, are splendidly equipped for the battle of life. And it is to the perfection of their adaptation that the prevalence of Gomphines with us is due.

Type
Articles
Information
The Canadian Entomologist , Volume 29 , Issue 7 , July 1897 , pp. 164 - 168
Copyright
Copyright © Entomological Society of Canada 1897

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References

page 165 note * Nomenclatural.—In the case of Aeshna vs. Gomphus I have examined the evidence and find it is as follows: Linne included all dragonflies known to him in one genus, Libellula. Fabricius (1775. Syst. Ent., pp. 420–426) divided the genus into three, Libellula, L. Aeshana, Fabr., and Agrion, Fabr., placing under Aeshna, among other species, L. grandis, L., and L. forcipata, L. It is worthy of note that he left L. vulgatissina, L., in Libellula. Illeger (1802. Magazin für Insekten kunde, p. 126) corrected the spelling to Aeschna, merely to accord with its etymology. Latreille was the first to designate types. He specifies (1802. Hist. Nat. Gust., Ms. III, 286) L. depressa, L, as the type of Libellula; L. vulgatissima, L., as the type of Aeshna, and L. virgo as the type of Agrion. With regard to the second, which alone concerns us here, L. vulgattisima, L., was described and figured by Latreille under the name “Aeshnma forcipata, Fabr.,” as was shown later by both Hagen and De Selys. Kirby's Catalogue of Neuroptera Odonata (1890) gives the correct synonymy and thus contains in itself the evidence which condemns the substitution it proposes. For if the type named by Latreille for Aeshna was vulgatissima, L., this species having been excluded by Fabricius when he founded the genus, cannot be its type. Leach (1818. Edinburgh Encycl. VIII. part 2, p. 726 of Amer. reprint) founded the genus gomphus, with L. vulgattisima L., for its type and placed under Aeshna. Fabr., the sole species L. grandis, L. However, Cuvier had previously (1798) characterized Aeshna (as pointed out by De Selys, C. R. Ent. Soc. Belg., 1890, p. CLXI.) and described under it the sole species grandis, L. This usage has since been universally followed until 1890, and one is glad to find there is now no reason for change.

I follow De Selys in using the name Ophiogomphus, Sel., which seems to have been quite properly given.

page 168 note * This will not apply to gaping exuvia in which originally parallel wing-cases have been forced apart.