444 



SCIENCE. 



[N. S. Vol. VII. No. ITCV. 



dergrowth or herbage, where they would 

 be almost unnoticed by the collectors. An 

 equalljr, if not more, dangerous time for but- 

 terflies of both sexes is during courtship 

 and pairing, when they are less on their 

 guard than at any other period, and those 

 actually paired (unless very well concealed 

 by close resemblance of their under side to 

 the immediate surroundings) have little 

 chance of escape. * Colonel Swinhoe has 

 mentioned to me that birds often do not seem 

 inclined to take the trouble to give chase to 

 flying butterflies, but sit merely watching 

 them, and this is in support of the view that 

 they more frequently adopt the easier plan 

 of attacking them when feeding, settling or 

 at rest. The frequency of the cases where 

 mimicry is confined to the female points 

 with some significance to the probability 

 that persecution is more directed against 

 that sex than against the male. 



(6) The presence of malodorous juices 

 in many insects is a matter of common ob- 

 servation, and is a protective property pos- 

 sessed by several entire groups, especially 

 among the Lepidoptera and Coleoptera. 

 There is abundant evidence as to the 

 prevalence of these secretions, and among 

 the Lepidoptera they are particularly de- 

 veloped in the butterflies of the groups 

 Danainse, Neotropinse, Acrseinse and Heli- 

 coninse, and also in some Papilioninte, as 

 well as in many moths of the groups 

 Agaristidge, Chalcosiidae, Arctiidte, Litho- 

 siidse, etc. The strength of the disagree- 

 able odor emitted is in some species very 

 great ;t Seitz, for instance, mentioning that 

 that the smell of the South American Heli- 

 conius besckei and Eueides aliphera extends 

 over a radius of several paces, and Wood- 

 Mason and De Niceville testifjang to the 



* It is not improbably in these circumstances 

 that the imperfectly mimetic but still ' ■warning ' 

 underside of the male in Perrhi/hris hecomes specially 

 serviceable {Cf. Disey, Trans. Ent. Soc. 1896, p. 71). 



t Cited by Haase, I. c, II., p. 101. 



same effect as regards the Indian Papilio 

 philoxenus and allied forms. When mo- 

 lested many of these offensively-smelling 

 species exude drops of a yellow or whitish 

 fluid which leave on anything they touch a 

 stain and odor difiBcult to remove, as I 

 have experienced in the case of the Mauri- 

 tian Eiqiilma euphone, the South African 

 Danainse, and various South African Aga- 

 ristidiB, Glaucopidse and Arctiidse. 



The origin and manner of acquisition of 

 these unsavory secretions have yet to be 

 discovered ; the suggestion (so much in- 

 sisted on by Haase) that these juices are 

 directly derived from those of similar 

 quality in the food plants of the larvte aris- 

 ing from the long-known circumstance that 

 some of the food plants of species in the- 

 protected groups are of an acrid or poison- 

 ous character, such as (e.g.) Asclepiads in 

 the case of many Danainse, and Aristolochia 

 in that of the inedible forms of Papilioninfe. 

 No doubt, too, the fact that the unpleasant 

 qualities are very often fully developed in 

 the larvae of the distasteful species — as I 

 have found with Danais clwysippiis and vari- 

 ous Acrsese — lends some weight to the sug- 

 gestion ; but at present nothing approach- 

 ing suflicient data can be brought forward 

 respecting the actual food plants to which 

 the protected groups, in contrast to the un- 

 protected, are thought to be resti-icted. It 

 cannot be gainsaid, as Professor Poulton 

 has pointed out,* that the food plants of 

 many of the distasteful European moths 

 do not belong to any poisonous or acrid 

 category ; and his own and Mr. Latter's 

 papers on Dicranura vinula alone amply 

 demonstrate what powerful acids can be 

 elaborated by a larva which flnds its food 

 in such innocuous plants as poplar and 

 willow. The supposed direct derivation of 

 the nauseous juices from the plants con- 

 sumed is thus plainly a matter that awaits 



*Proc. Zool. Soc. Loud., 1887, pp.198, etc., and, 

 Nahire, 4th Nov,, 1897, p. 3. 



