THE AMERICAN ENTOMOLOGIST. 



four paws, while the Mottled Tortoise-beetle 

 always confines himself to two. And what is 

 very remarkable, there is a species found in 

 Hindostan which is marked almost exactly like 

 our insect.* 



Of course, in such a case as this, the re- 

 semblance must be purely fortuitous ; for the 

 discrepancy in size is so enormously great, that 

 it is impossible to believe that any, even the 

 stupidest animal, could mistake this Tortoise- 

 beetle for a real tortoise. In several other cases, 

 however, of entomological mimicry, where a 

 nest-building insect and its parasite have a 

 strong general resemblance, it has been sup- 

 posed by authors that this is a beautiful pro- 

 vision of nature, in order to enable the parasite 

 to penetrate without danger into the nest of the 

 other insect, and deposit its eggs there without 

 interruption on the part of the uest-builder. It 

 is coutended, in fact, that, from the great resem- 

 blance between the two, the nest-builder mis- 

 takes the parasite for an individual belonging 

 to its own species. So far as regards social in- 

 sects, such as Yellow Jackets and Humble-bees, 

 this theory will do very well; for as there are 

 here a great number of individuals owning a 

 nest in common, it is reasonable to suppose 

 that a parasite, that strongly resembled the 

 members of the community, might occasionally 

 slip in unobserved by any one of them. But 

 with solitai-y nest-building insects the case is 

 very different. Here there is but a single in- 

 dividual—the female — that constructs the nest, 

 the male taking no part whatever in this pro- 

 cess; and even if she mistook the parasite for 

 an individual belonging to her own species, she 

 would be just as unwilling for the stranger to 

 enter her own private and peculiar nest, as a 

 heu robin would be for another hen robin to 

 make herself at home in the nest which she has 

 herself labored to construct. Indeed, the num- 

 ber of parasites that resemble the insects upon 

 which they are parasitic is so exceedingly small 

 — certainly not exceeding the one hundredth 

 l)art of the whole number of parasites — that 

 here we are compelled, as in the case of our 

 tortoise-beetle, to attribute the seeming mimicry 

 to chance. 



There are, however, very numerous instances 

 of mimicry among insects, where the mimicker 

 gains a manifest advantage by wearing the liv- 

 ery of some other organism, and where conse- 

 quently the imitation must be attributed, not 

 to chance, but to design. Such are those well- 

 known cases among the span-worms or mcasur 



•Westw. Introd., I, p. 379 and p. 377, Fig. 



ing-worms, where the larva is of the same dingy 

 brown color as the twig upon which it rests, 

 and where it habitually stretches itself out in a 

 straight line at angles with the twig, remaining 

 all the time perfectly stiff and immovable, so 

 that even the acute eyes ot the practised ento- 

 mologist are sometimes deceived by the ma- 

 noeuvre, and mistake the living and breathing 

 worm for a bit of dead and dry stick. Such 

 also is the case of the Stick-bug, otherwise 

 known as " Walking-stick," which we referred 

 to on page 58 of our First Volume, and wliich 

 has the singular habit of projecting forwards its 

 two front legs and its antennte all in a straight 

 line, so that the whole insect, remaining immov- 

 able in this posture, looks like a straight stick, 

 as represented in the middle of the right hand 

 margin of the cover to our Magazine. Such 

 again are those other cases, where insects, for 

 instance our common Catydid, habitually living 

 among green leaves, imitate those leaves, not 

 only in the general coloring of their bodies, but 

 in the very shape and even in the style of vein- 

 ing of their wings. The very peculiar and re- 

 markable case of the Imitative Butterflies, we 

 have already treated of in a separate article.* 

 Unlike the four or five species of Tortoise- 

 beetles, which we figured and described in our 

 recent article on the Insects infesting the Sweet 

 Potato, the Clubbed Tortoise-beetle (Fig. 1) 

 infests, not the Sweet, but the common Irish 

 Potato. In the West it is rather a rare insect; 

 for in the conr.se of twelve years' collecting we 

 have only met with some half dozen specimens, 

 and we arc entirely unacquainted with the 

 larva. Mr. J. B. Ilartwell, however, of Wilkin- 

 sonville, Massachusetts, frequently finds the 

 perfect beetle feeding on the leaves of Potatoes 

 and Tomatoes, though not in sufficient numbers 

 to be seriously injurious; and Mr. Blanchard, 

 of the same State, meets with it quite commonly 

 both on the cultivated Potato and on the Bitter- 

 sweet, a weed belonging to the same genus 

 (Solanum) as the Potato. Moreover, Isaac 

 Hicks, of Long Island, N. Y., has transmitted 

 to us no less than twenty-six specimens, all 

 found upon potato-stalks in his neighborhood. 

 Thus, as the Tortoise-beetles previously figured 

 by us mostly infest plants belonging to the 

 Convolvulus 'Famih', such as Sweet Potato and 

 Morning Glory, the species that we have now 

 to do with seems to be confined to plants be- 

 longing to the closely allied Solanum Family, 

 such as the Potato, the Bitter-sweet and the 

 Tomato. It is remarkable that the East Indian 



•AsiEK. Entomologist, Vol. I, pp. 189-193. 



