Heliconiidae

“ In fact, one finds, as one would have expected, that every butterfly has the gait best suited to the kind of place that he lives in. Heliconius, one of the very slowest genera on our continent, is particularly at home while flying through the densest copses. It is perfectly natural that such a butterfly as a grapta, matched to the colors of the ground, should hurry, in flying from one safe spot on the ground to another, but the case of Heliconius is very different. ”

“ The species is still very rare in collections; our own, a fine pair, were received from Van Diemans Land.
Although unacquainted with the larva, and pupa state of this species, nature has stamped the perfect insect with the image of that group she intends it to represent. Its long, narrow, anterior wings, almost transparent, immediately reminds even the unpractised entomologist of the Heliconian butterflys; while the analysis of the genus Papilio, confirms this idea, by shewing that Cressida is the Heliconian type. ”

“ Under these circumstances, it is evident that any other butterfly of a group which birds were accustomed to devour, would be almost equally well protected by closely resembling a Heliconia [81] externally, as if it acquired also the disagreeable odour; always supposing that there were only a few of them among a great number of the Heliconias. If the birds could not distinguish the two kinds externally, and there were on the average only one eatable among fifty uneatable, they would soon give up seeking for the eatable ones, even if they knew them to exist. ”

“ Having first pointed out that the Heliconea butterflies are a numerous, flourishing race, whilst those species that imitate them are poor in numbers, he says, “What advantages the Heliconidæ possess to make them so flourishing a group, and, consequently, the object of so much mimetic resemblance, it is not easy to discover. There is nothing apparent in their structure or habits which could render them safe from persecution by the numerous insectivorous animals which are constantly on the watch in the same parts of the forest which they inhabit. ”

“ It is probable they are unpalatable to insect enemies. Some of them have glands near the end of the abdomen which they protrude when roughly handled; it is well known that similar organs in other families secrete fetid liquids or gases and that these serve as a protection to the species. They have all a peculiar smell. I never saw the flocks of slow-flying Heliconidæ in the woods persecuted by birds or dragon-flies, to which they would have been easy prey ”

“ As the Heliconidae are coloured in their usual manner, whilst the others depart from the usual colouring of the groups to which they belong, it is clear that the latter are the imitators, and the Heliconidae the imitated. Mr. Bates further observed that the imitating species are comparatively rare, whilst the imitated abound, and that the two sets live mingled together. From the fact of the Heliconidae being conspicuous and beautiful insects, yet so numerous in individuals and species, he concluded that they must be protected from the attacks of enemies by some secretion or odour ”

“ As it is among butterflies that instances of mimicry are most numerous and most striking, an account of some of the more prominent examples in this group will first be given. There is in South America an extensive family of these insects, the Heliconidæ, which are in many respects very remarkable. They are so abundant and characteristic in all the woody portions of the American tropics, that in almost every locality they will be seen more frequently than any other butterflies. ”

“ Powers of Vision in Land Mollusca.—The Helicidae are undoubtedly very short-sighted. Seldom emerging from their retreats except in twilight and darkness, they are naturally myopic, and see better in a subdued than in a bright light. Experiment has shown that a Helix can perceive an object better at 6 centimetres distance in a weak light than at 4 or 5 millimetres in a strong one. Cyclostoma elegans and Paludina vivipara are comparatively long-sighted, perceiving objects at a distance of 20 to 30 centimetres. ”

“ In spite of certain resemblances in the early stages between the insect we are considering and the early stages of some of the Heliconians, and in spite of the shape of the wings, which are remarkably elongated, there are structural peculiarities enough to compel us to keep this insect in the ranks of the Nymphalinæ, where it has been placed for sixty years by very competent and critical observers. ”

“ No operculum; a thin epidermis.—Obs. The land shells composing this genus are found in all parts of the world; the common snail, H. Aspersa, is well known as a destructive animal in our gardens. The genera Helix, Achatina, Bulinus, Clausilia, Anostoma, &c., have been united under one generic name by De Ferussac, and again divided under the following sub-generic names, each of which we shall illustrate by a figure. Genus Helix: Sub-genus 1, Helicophanta, consisting of species with large apertures, like Vitrina; Helix brevipes. S. gen. 2, Cochlohydra, Succinea Amphibia, Drap. ”

“ Mimicry and Protective Coloration.
Cases of Mimicry, or protective resemblance, when a species otherwise defenceless adopts the outward appearance of a better protected species, are rare among the Mollusca. Karl Semper [150] mentions an interesting case of the mimicry of Helicarion tigrinus by Xesta Cumingii, in the Philippines. It appears that all [67] species of Helicarion possess the singular property of shaking off the ‘tail’ or hinder part of the foot, when seized or irritated. Specimens captured by collectors, Hel. ”

“ Under such conditions it might well be supposed that instances of close resemblance between different species would be numerous, and this in effect is what we find.
As in Asia with its Euploeines and Danaines, and in Africa with its Danaines and Acraeines, so in S. America are the fashions set by two dominant groups of models. These are the Heliconinae and the Ithomiinae, both peculiar to this region and both characterised, like the Old-world Danaids, by slow flight and great tenacity of life. Both live on poisonous plants—the Heliconines on Passifloras and the Ithomiines on Solanaceae. ”

“ Bates also found a number of pairs of species of different genera of Heliconidæ, which resembled each other quite as closely as did the other mimicking species he has described; and since all these insects appear to be equally protected by their inedibility, and to be equally free from persecution, it was not easy to see why this curious resemblance existed, or how it had been brought about. ”

“ In colouration there are several types in the different genera of Heliconidæ. The genus Mechanitis is generally of a rich semi-transparent brown, banded with black and yellow; Methona is of large size, the wings transparent like horn, and with black transverse bands; while the delicate Ithomias are all more or less transparent, with black veins and borders, and often with marginal and transverse bands of orange red. These different forms are all copied by the various species of Leptalis, every band and spot and tint of colour, and the various degrees of transparency, being exactly reproduced. ”

“ Helcion, 405; protective coloration, 69 Helcioniscus, 405 Hele, F. M., on Hyalinia, 33; on Stenogyra, 34 Helicarion, 309, 316, 325, 332, 440; radula, 232; habits, 45, 67 Helicidae, radula, 232, 234 Helicina, 305, 306, 316–327, 338–358, 410; origin, 21; exterminated by cold, 24 Helicophanta, 335, 336, 441, 441 Heligmus, 449 Helix, 441; toothed aperture, 63; protective coloration, 70; variation, 87; carbonic acid, 163; eye, 181, 183; food, 179; smell, 194; jaw, 211; distribution, 285; tenacity of life, 37; breeding, 129 Helix alternata, 340 ”

“ Helicidae and Naninidae are equally deficient, the former, indeed, attaining some numerical predominance in the extreme south, but the species are nearly all insignificant in size and colouring. It is only in Madagascar that Helix asserts itself. Arion, Limax, Hyalinia, Clausilia, and a [329] number of other genera abundant along the Mediterranean, are either altogether absent, or are very scantily represented. Land operculates, so characteristic of other tropical countries, are almost entirely wanting. ”

“ All the insects that have special means of protection, by which they are guarded from the attacks of insectivorous mammals and birds, have peculiar forms, or strongly contrasted, conspicuous colours, and often make odd movements that attract attention to them. There is no attempt at concealment, but, on the contrary, they appear to endeavour to make their presence known. The long narrow wings of the Heliconii butterflies, banded with black, yellow, and red, distinguish them from all others, excepting the mimetic species. ”

“ Many of the species are beautiful objects on account of the brilliancy of their colouration, and some are remarkable for the variation they exhibit in this respect. Species of Helicidæ are found in nearly every part of the world and in all situations, from sea-level to an altitude of 12,000 feet. They are fond of moisture, and in hot and dry weather retire within their shells, remaining torpid until the return of dew and rain. ”

“ This is a tropical subfamily, and has only one representative within the borders of the United States. Heliconius charitonius, the Zebra butterfly, is a slender, long-winged, black-and-yellow species common along the roadsides of southern Florida. This butterfly has such an evil taste and odor that no known animal will eat it. The eggs are deposited upon the passion-flower vine; the young larva is hairy, but the mature caterpillar is provided with a great number of branching spines. The chrysalis is dark brown and of an odd shape; it makes a peculiar creaking sound by moving its abdomen. ”

“ The Heliconidae, a tribe of butterflies peculiar to tropical America, with long, narrow, weak wings, are distasteful to most animals: I have seen even spiders drop them out of their webs again; and small monkeys, which are extremely fond of insects, will not eat them, as I have proved over and over again. Probably, in consequence of this special protection, they have not needed stronger wings, and hence their weak flight. They are also very bold, allowing one to walk close up to flowers on which they alight. ”

“ Wings hyaline, clouded with irregular waved bars of blue; body, thorax, and macular band round the margin of the inferior wings, orange.
The diurnal or Heliconean Hawk-mouths, form one of the most natural and remarkable groups among Lepidopterous insects. They fly during the heat of the day; and, (as representing in their own family the tribe of Phalænides) they have much of the general appearances of moths. In their slow flight, long transparent wings, and proneness to imitate death on being handled, they afford a most beautiful analogy to the Heliconian Butterflys. ”

“ I have kept alive in my room specimens of Heliconidæ for six and eight months, while mud-dauber wasps have repeatedly wintered in my room, and have witnessed the outcomings of spring broods. Thus, it not infrequently happens that these insect mothers are gratified by a sight of their offspring, though sometimes they evince painstaking care and solicitude toward creatures which they will never see. ”

“ Bates notices fifteen distinct species of Pieridæ, belonging to the genera Leptalis and Enterpe, each of which closely imitates some one species of Heliconidæ, inhabiting the same region and frequenting the same localities. It must be remembered that the two families are altogether distinct in structure. The larvae of the Heliconidæ are tubercled or spined, the pupae suspended head downwards, and the imago has imperfect forelegs in the male; while the larvæ of the Pieridæ are smooth, the pupæ are suspended with a brace to keep the head erect, and the forefeet are fully developed in both sexes. ”

“ If they owe their flourishing existence to this cause it would be intelligible why species whose scanty number of individuals reveals a less protected condition, should be disguised in their dress, and thus share their immunity. Is it not probable, seeing the excessive abundance of the one species and the fewness of individuals of the other, that the Heliconea is free from the persecution to which the Leptalis is subjected?” [107]
No sooner was this suggestion made than naturalists all over the world began to test it, or rather to say that it ought to be tested. ”

“ By the larger species this loss will be hardly felt; to the smaller it will mean the most dreadful persecution resulting in a loss of half the total population. But, let the two species become superficially alike, so that the birds see no difference between them. The quota of 500 will now be taken from a combined population of 101,000 butterflies, and if proportionate numbers of each suffer, then the weak species will only lose five individuals instead of 500 as it did before. Now we know that the different species of Heliconidae are not equally abundant, some being quite rare ”

“ So general are these deceptive resemblances throughout nature, that it is often difficult to determine whether sexual preferences or the preservation of mimetic forms has been most potent in moulding the form and coloration of species, and in some the two forces are seen to be opposed in their operation. Thus in some butterflies that mimic the Heliconidae, the females only are mimetic, the males retaining the normal form and coloration of the group to which they belong. ”

“ The various forms of Heliconius erato are well known to entomologists. They are strikingly distinguished by the colours of the strong comb-like marking on the hind wing, which may be red, yellow, green or blue. In various parts of the distribution in South America sometimes two and sometimes three of these distinct types co-exist. [7]
The distribution of the varieties of Noctua castanea typifies a large range of cases. The form which is reckoned the normal of the species has red fore-wings. It is practically restricted to Great Britain and Germany, according to Tutt. ”