74 



ENTOMOLOGY 



Eversible hypodermal glands of many kinds are common in larvae of 

 Coleoptera and Lepidoptera. The larvae of Lina 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. 



PIG. 103. Osmeterium of Papilio FIG. 104. Ventral aspect of worker honey bee, show- 

 polyxenes. ing the four pairs of wax scales. After CHESHIRE. 



103) which diffuses a characteristic but indescribable odor that is 

 probably repellent. The larva of Cerura everts from the under side of 

 the neck a curious spraying apparatus which discharges formic acid. 



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 dis- 

 seminate an alluring odor from 

 scent tufts on the middle legs. 

 Female saturniid moths (as cecro- 

 pia and promethea) entice the 

 males by means of a characteris- 



lp, labial palpus; m t mandible; mp, maxillary tremity of the abdomen. In 

 palpi; o, ocelli; s, spinneret. . ... ... 



lycaenid caterpillars, an eversible 



sac on the dorsum of the seventh abdominal segment secretes a sweet 

 fluid, for the sake of which these larvae are sought out by ants. 



Wax Glands. Wax is secreted by insects of several orders, but es- 

 pecially Hymenoptera and Hemiptera. In the worker honey bee the 

 wax exudes from unicellular hypodermal glands and appears on the 



