INTRODUCTION. 51 



puscularia by Latreille. The latter term has been 

 applied to them, because many of the most conspicu- 

 ous species are observed on the wing chiefly during 

 the morning and evening twilight ; others, however, 

 do not shun the " garish eye of day," but may be seen 

 darting about in the sunshine in company with but- 

 terflies and other exclusively diurnal kinds. Their 

 flight is exceedingly rapid, and continued nearly in a 

 direct line, somewhat like that of a bird, differing 

 greatly in this respect from the devious zig-zag motion 

 of most other lepidoptera, many of which seem to 

 float rather than to be impelled by muscular exertion. 

 The wings, notwithstanding, are rather of small size 

 compared with the body ; but the thickness and mas- 

 siveness of the latter admits of great development in 

 the muscles by which these organs are moved, and 

 a momentum is thus communicated to them more 

 than sufficient to compensate for their somewhat 

 limited extent of surface. By their rapid vibration, 

 the taper body of the insect is poised in the air like 

 that of a hawk, while it hovers over the petals of a 

 flower, and extracts the mellifluous juices by means 

 of its long tubular proboscis. The resemblance just 

 alluded to has caused them to be named hawk- 

 moths ; and as many of them, when thus hoveling 

 in the air, produce a humming sound, and in this 

 respect, as well as in feeding on the wing and in the 

 darting rapidity of their movements, bear some like- 

 ness to humming-birds, a few are named after these 

 " winged gems," and are well known under the some- 

 what composite title of humming-bird hawk-moths. 



