192 



THE AMERICAN ENTOMOLOGIST. 



tional pattern is an almost exact connterpart of 

 the Danais that is figured above.* So servilely 

 indeed does it mock the other species, that 



[Fiff. 133.] 



Colors— Coppery-red, lilack and Avhite. 



Prof. Jaeger, in his Life of N'orth American 

 Insects, has actually favored his readers with a 

 wood-cut of it, and gravely informs them that 

 its scientific name is Danais a7xhip2^us! And 

 yet— close as the resemblance is, and common 

 as both species are — no author seems hitherto 

 to have observed, that we have here a clear case 

 in North America of that very same curious 

 imitative process, which eight years ago was 

 so beautifully expounded and explained by Mr. 

 Bates, so far as regards the butterflies of the 

 Valley of the Amazon ! 



The larva of this Z)i.«tppMS butterfly, of which a 

 drawing will be found below (Fig. 134 a,),occurs 



[Fig. 131.] 



most commonly on ditferent species of willow, 

 but is often found on the closely allied poplar 

 and Cottonwood (populus) and occasionally on 

 the plum. There is another larva, which 

 resembles it so closely that the two can scarcely 

 be distinguished, and which normally, like most 

 species of the genus Nymphalis, inhabits the 

 willow, but is occasionally met with on scrub- 



*In Figure 133, the left wings represent the npper surface, 

 and the right wings, which are detached from the body, 

 represent the ioAver surface. Q'he diflerence in the colora- 

 tion of the two surfaces is hut slight in this species, neither 

 does it amount to much in the Archipptt^ butterfly; but in 

 "Ome butterflies it is very considerablv. 



oak {Quercus ilicifoUd), on whortleberry, on 

 cherry, and on plum, fi-om which last tree we 

 have ourselves bred a single specimen. This 

 second larva produces the Ursula butterfly 

 {Nymphalis vrsula, Fabr.). a species belonging 

 to the same genus as the D('«yjp«« butterfly, but 

 dificring widely therefrom in being of a sombre 

 blue-black color, with its wings bordered both 

 above and bolow with blue, and below with a 

 series of dull orange spots inside the blue 

 border. Place this insect side by side with the 

 Archippus butterfly, and everybody would say 

 at once that no two species could possibly be 

 more unlike in the general style of their colora- 

 tion. Clearly, therefore, it cannot be considered 

 as in any wise mimicking the latter. Now, the 

 Ursula butterfly is found everywhere through- 

 out the Northern States wherever the Disippus 

 butterfly is met with ; and yet, while the latter 

 is a common and abundant species, the former 

 is everywhere quite rare.* To what arc we to 

 attribute this fact? It can scarcely be owing to 

 structural diflerences in tlic external organiza- 

 tion of the two species ; for the two belong to 

 one and the same genus. It surel)'^ cannot be 

 becanse the larviB of the former are more 

 exposed to the attacks of predaceous animals 

 than those of the latter; for they inhabit the 

 same, or very nearly the same trees, and in size, 

 shape and general coloration the two are almost 

 exactly alike. Certainly it can not be because 

 the pupa; of one species are more subject to be 

 devoured by birds, insects, etc., than those of 

 the other tpecies ; for it is impossible to tell one 

 pupa from another, when placed side by side. 

 The only cause to which we can reasonably 

 attribute the great abundance of the Disippus 

 butterfly and the comparative rarity of the 

 Ursula butterfly is, that the foimer mimicks the 

 Archip2ms butterfly, as has been shown above, 

 and is consequently often mistaken by tree-frogs, 

 dragou-flies, Asilus flies and other beasts of prey 

 for its unsavory prototype and allowed to escape 

 with impunity ; while the latter, being too hon- 

 est a bug to assume a fraudulent and deceptive 

 disguise, is ruthlessly devoured by every insect- 

 eating animal that can get hold of him. 



Figure loi 6, shows the Disippus butterfly iu 

 the pupa state, with the strange knife-edged 



* As we do not desire that the relative abundance of these 

 two species should depend upijn our authority alone, we 

 subjoin c nlirmatory evidence of the fact. 



According to Mr. J. A. Lintner ursitla is "rare" and 

 disippus islound abundantly in New York. {Proc. Ent. Soc. 

 Phil., III., pp. Ij3— t.) According to Mr. J. ICirkp.atrick 

 Ursula is "rather rare" and disippits " common in the 

 fall " in Ohio. (Ibid , p. 3-20.) According to Mr. Sam. H. 

 Scudder, Ursula is " I'ather rare" and disijjpus is "com- 

 mon" in Xe\v England. {Proc. Essex Inst,, 11[., p. I(i5.) 

 According to Mr. Bdlings.wbo does not seem to have met 

 with any ursula at all, disippusis " veiy common from July 

 to October" ju Canada West. {Canail, Entom., I., p. 45.) 



