366 MODERN CLASSIFICATION OF INSECTS. 
acute, and in others broader, and furnished on each side with a brush : 
others, again, vary from the types of the family by having the wings 
more or less denuded of scales (Sesia), whence the species, which are 
of smaller size than the typical species, have received the names of 
S. fusiformis and bombyliformis, in allusion to their analegical resem- 
blance to drones or Bombylius. These last-mentioned species, as well 
as those with tufted abdomens, fly during the day, the latter thence 
obtaining the name of humming-bird hawk moths ; whereas the others 
fly during the twilight, darting about with the greatest rapidity, or 
hovering, hawk-like, in front of flowers, from which they extract the 
nectar with the assistance of their elongated tongue. Mr. Stephens 
has separated these day-flying species as a distinct family, Sesiide ; 
but the identity in their more decided characteristics, and especially 
the conformity in their preparatory states*, are sufficient to prove them 
to belong to the same natural group, constituting, however, so many 
aberrant genera: thus, whilst Macroglossa bears a relation to certain 
Noctuidz, Sesia approaches /Egeria; some of the Smerinthi, espe- 
cially from North America, approach certain Bombycide, in which we 
also find an equal diminution in the length of the spiral tongue, and in 
which the hind wings in repose extend beyond the fore wings at the 
sides: thus, we perceive that the preparatory states afford the best 
characters of the family. 
The caterpillars of the typical species are remarkable for the atti- 
tude which they ordinarily assume, whence they have obtained the 
generic name of Sphinx, from their supposed resemblance to the 
figures of that fabulous creature. Some of these caterpillars are also 
remarkable for the faculty they possess of elongating and contracting 
the three anterior segments of the body, giving them somewhat the 
appearance of the proboscis of an elephant, whence they have ob- 
tained the name of elephant sphinxes. By the French they are named 
chenilles cochonnes (fig. 102.10. and 11. front of body of larva of 
Metopsilus Elpenor). It will be seen by referring to a preceding page 
(328.), that Dr, Horsfield divides the Sphingide (which he considers 
* Sesia (S, bombyliformis, &e.) is certainly the most aberrant genus in the 
family, the caterpillars being slightly pilose; and when about ten days old, they 
have several furcate spines upon each segment of the abdomen, that entirely dis- 
appear when they are full-fed, according to information giyen by Mr. Dale to 
Mr. Curtis. The full-grown caterpillar is however evidently Sphingideous. The 
perfect insects make a loud humming during flight. 
