44 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 68 



(d) GLANDS IN THORAX OF CERTAIN MOTHS 



Fenn (1890) reports "that Liparis salicis has the power, when 

 annoyed, of ejecting a pale greenish or yellowish fluid from (appar- 

 ently) glands, situated on the thorax above the eyes." In Arctia caia 

 there are two glands located just in front of the red " collar " of 

 the thorax and they secrete drops of greenish fluid, which is acrid 

 and is distasteful to birds. 



Reid (1891) reports that acrid glands are possessed by a number 

 of Lepidoptera besides the above named species, but he thinks that 

 the secretion is to soften the cocoons so that the imagoes may more 

 easily emerge, rather than primarily to serve as a protective fluid 

 during the adult life. 



5. ANDROCONIA OR SCENT SCALES OF MALE BUTTERFLIES AS SCENT- 

 PRODUCING ORGANS 



Deschamps (1835) was the first to study the scent scales of butter- 

 flies, although he credits the discovery of them to Baillif about 1825. 

 Deschamps found them in 37 species, representing three genera. 

 He called them plumules on account of their feathery tips and ^ob- 

 served that they are much smaller than ordinary scales and are found 

 only on the wings of insects. 



In order that an intelligible description of the scent scales may 

 be presented at the outset we shall quote Kellogg (1894) who says: 



The androconia are found almost without exception on the upper side of 

 the wings, and are more commonly met with on the forewings than on the 

 hindwings. They are often found in certain limited spots, or in folds of the 

 wings. This is usually the case among the Nymphalidae, a familar example 

 being the pouch of the hindwings of Danais archippus. Among the Papil- 

 ionidse they are limited to folds on the wings, as those found along the inner 

 margin of the hindwings of Papilio. In the Hesperidae the androconia are 

 found in costal folds or in the familiar discal spots or streaks. Among the 

 Lycaenidae and Pieridae they are most often scattered over the wing-surface 

 being concealed in the general wing covering. 



Mayer (i860) observed the scent scales while examining the 

 " powder " on the wings of various butterflies. 



Watson (i865a-b, i868a-b) found the scent scales usually on the 

 upper side of the wings of males. He found them in 507 species, 

 representing 30 genera, belonging to six families. He asserts that 

 these scales are so constant in different individuals of the same 

 species as to be of valuable use in taxonomy. He thinks that they 

 are to aid in respiration and also may be inflated with air and thus 

 serve as a buoyancy. 



