82 EN TOMOLOGY 
glands (Fig. 146); this fluid in Brachinus, and occasionally 
in Galerita janus and a few other carabids, volatilizes explo- 
sively upon contact with the air. When one of these “ bom- 
bardier-beetles ’’ is molested it discharges a puff of vapor, 
accompanied by a distinct report, reminding one of a minia- 
ture cannon, and this performance may be repeated several 
times in rapid succession; the vapor is acid and corrosive, 
staining the human skin a rust-red color. 
Hic. lor. 
Individuals of a large South American 
‘ 
Brachinus when seized “ immediately 
began to play off their artillery, burning 
and staining the flesh to such a degree 
that only a few specimens could be cap- 
tured with the naked hand, leaving a 
mark which remained for a considerable 
time.’ (Westwood. ) 
As malodorous insects, Hemiptera are 
Osmeterium of Papilio notorious, though not a few hemipte- 
a rous odors are (apart from their associa- 
tions) rather agreeable to the human olfactory sense. Com- 
monly the odor is due to a fluid from a mesothoracic gland or 
glands, opening between the hind coxe. 
Eversible hypodermal glands of many kinds are common in 
larvee of Coleoptera and Lepidoptera. The larve of Melasoma 
lapponica, among other Chrysomelide, evert numerous paired 
vesicles which emit a peculiar odor. The caterpillars of our 
Papilio butterflies, upon being irritated, evert from the pro- 
thorax a yellow Y-shaped osmeterium (Fig. 101) which dif- 
fuses a characteristic but indescribable odor that is probably 
repellent. The larva of Cerura everts a curious spraying 
apparatus from the under side of the neck. 
Alluring Glands.—Odors are largely used among insects to 
attract the opposite sex. The androconia of male butterflies 
have already been spoken of. Males of Catocala concumbens 
disseminate an alluring odor from scent tufts on the middle 
legs. Female saturniid moths (as cecropia and promethea) 
