100 



AN INTRODUCTION TO ENTOMOLOGY 



clothing hair, is that there is connected with it, in addition to the 

 trichogen cell which produced it, the gland cell which opens through it . 

 In most of the published figures of glandular setae there is no indi- 

 cation that these organs are supplied with nerves ; but in some cases 

 a nerve extending to the gland cell is clearly shown. This condition 

 may be found to be general when more extended investigations of 

 glandular cells have been made. The best known kinds of glandular 

 setae are the following : 



Venomous setce and spines. These are best known in larvse of 

 Lepidoptera, several common species of which possess stinging hairs; 

 among these are Lagoa crispata, Sibine stimulea, Automeris io, and 

 the brown-tail moth, Euproctis chrysorrhoea. 



Androconia. The term androconia* is applied to some peculiarly 

 modified scales on the wings of certain male butterflies. These are 

 the outlets of glands, which secrete a fluid with an agreeable odor; 

 the supposed function of which is to attract the opposite sex, like the 

 beautiful plumage and songs of male birds. The androconia differ 



marvelously from ordinary scales in the 

 variety of their forms (Fig. 115). They 

 usually occur in patches on the upper sur- 

 face of the fore wings; and are usually 

 concealed by other scales; but they are 

 scattered in some butterflies. The most 

 familiar examples of grouped androconia 

 are those that occur in the discal stigma of 

 the hair-streaks, in the brand of certain 

 skippers and in the costal fold of others, 

 and in the scent-pouch of the male of the 

 monarch butterfly. 



The specific scent-glands of females 

 The well-known fact that if an unfertilized 

 female moth be confined in a cage or 

 otherwise in the open many males of the 



Fig. 115. Androconia from the same species as the female will be attracted 

 wings of male butterflies (After 

 Kellogg). to it, and sometimes evidently from a great 



distance, leads to the conclusion that there 



must emanate from the female a specific odor. The special glands 

 producing this odor have not been recognized. 



Tenent hairs. In many insects the pulvilli or the empodia are 

 clothed with numerous hairs that are the outlets of glands which 



*Androconia : aiidro- (a.vf)p, avfy>6s), male; coiiia (KOVIO.), dust. 



