ANATOMY AND PHYSIOLOGY 



from attack. Larvae of Cimbex when disturbed squirt jets of a watery 

 fluid from glands opening above the spiracles. Many Carabidae eject a 

 pungent and often corrosive fluid from a pair of anal glands (Fig. 146) ; 

 this fluid in Brachinus, and occasionally in Galerita janus and a few other 

 carabids, volatilizes explosively upon contact with the 

 air. When one- of these "bombardier-beetles" is 

 molested it discharges a puff of vapor, accompanied 

 by a distinct report, reminding one of a miniature 

 cannon, and this performance may be repeated several 

 times in rapid succession; the vapor is acid and corro- 

 sive, staining the human skin a rust-red color. Indi- 

 viduals 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 captured with the naked 

 hand, leaving a mark which remained for a consider- 

 able time." (Westwood.) 



As malodorous insects, Hemiptera are notorious, 



though not a few hemipterous odors are (apart from their associations) 

 rather agreeable to the human olfactory sense. Commonly the odor is 

 due to a fluid from a mesothoracic gland or glands, opening between the 

 hind coxae. 



Eversible hypodermal glands of many kinds are common in larvae of 



PIG. ioo. Sting- 

 ing spines of a cater- 

 pillar, Lagoa crispata. 

 After PACKARD. 



FIG. 10 1. Osmeterium of Papilla 

 polyxenes. 



FIG. 102. Ventral aspect of worker honey bee, show- 

 ing the four pairs of wax scales. After CHESHIRE. 



Coleoptera and Lepidoptera. The larvae of Melasoma lapponica, among 

 other Chrysomelidae, evert numerous paired vesicles which emit a peculiar 

 odor. The caterpillars of our Papilio butterflies, upon being irritated, 

 evert from the prothorax a yellow Y-shaped osmeterium (Fig. 101) which 

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