66 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Larva and Pupa of Caligo memnon.* — F. L. Davis gives an 

 account of his observations on the development of Caligo memnon at 

 Behze, British Honduras. The larvas avoided sunhght and crawled 

 from a distance about sundown to their food-plant, the banana. In the 

 position for pupation thej hang head downwards, with only the anal 

 extremity attached to a small web. The colours of the larvte are care- 

 fully described. Springing from the central dorsal black line are what 

 appear to be very sharp and pointed black spines standing vertically 

 upwards. But though they look formidable, they are quite soft and 

 easily bent. Eight " horns " surround the edsje of the head. 



'&' 



Prote'"tive Value of Mimetic Resemblance.f — E. Rabaud has 

 studied the case of the larvae of Rhogas, a hymenopterous parasite on 

 lepidopterous caterpillars, in regard to the supposed protective re- 

 semblance of the caterpillar skin to a Campopleg cocoon. The larvae of 

 Rhogas pupates within the body of its host, which by that time is a 

 mere dry and empty skin. The anterior part of the skin usually 

 withers and shrinks, while the posterior part inhabited by the larvae 

 keeps its caterpillar shape. The author examined numbers of Fieris 

 brassicse caterpillars infested by the parasite, and came to the conclu- 

 sion that the resemblance was quite fortuitous. For every skin that 

 looked deceptively like the Campopleg cocoon, there were many others 

 that looked quite different, though some of them showed a very im- 

 perfect resemblance. The degree of resemblance depended in part on 

 the extent to which the anterior portion of the caterpillar's body was 

 eaten away, and on various external circumstances. From the per- 

 sistence of the very numerous imperfect forms the author argues that 

 mimetic aspect has no protective value. 



Scent-organs in Male Danaine Butterflies.^ — H. Eltringham has 

 previously described the scent-glands and brushes in Amauris niavim 

 Linn. Each gland consisted of several cells communicating on the 

 upper surface of the wing with a projection which the author called a 

 " scent-cup." This bore a cover pierced by a median pore. Tufts of 

 setai in an eversible sac form two brushes at the hinder end of the 

 abdomen, and part of the brush-bag contained cells which produced 

 dehcate threads that break up into dust. The butterflies apply their 

 brushes to the glandular patches on the hind-wings, and the dust may 

 assist in the diffusion of the scent. 



Eltringham proceeds to describe corresponding structures in other 

 species. Neither wing-glands nor dust-producing devices are invariably 

 present ; the brush itself, and not the wing, may produce the scent 

 material, or at least exhibit a glandular structure, whilst the dust may 

 be produced by the wing and not by the brush, and in the pupal instead 

 of in the imaginal state. An account is given of the state of affairs in 

 five species of Amauris, two species of Danaida, and some other butter- 

 flies. There is no direct evidence that a scent is produced, but the 

 argument from analogy is strong. 



* Trans. Entomol. Soc. London, pt. 2 (1915) pp. 198-200 (1 pi.). 



t Bull. Soc. Zool. France, xl. (1915) pp. 56-63 (1 fig.). 



+ Trans. Entomol. Soc. London, 1915, pp. 152-76 (10 pis.). 



