Ephemeroptera

“ The latter has established, for all the Palaeozoic insects, an order Palaeodictyoptera, there being a closer similarity between the fore-wings and the hind-wings than is to be seen in most living orders of Hexapoda, while affinities are shown to several of these orders—notably the Orthoptera, Ephemeroptera, Odonata and Hemiptera. It is probable that many of these Carboniferous insects might be referred to the Isoptera, while others would fall into the existing orders to which they are allied, with some modification of our present diagnoses. ”

“ Pseudogyna migrans: in Aphids, the winged descendants of the stem- mother (fundatrix) through which the species is spread.
Pseudogyna pupifera: in Aphids, the last generation of p. gemmans, which produces the true sexes.
Pseudogyna: a female that reproduces without impregnation.
Pseudo-halteres: the rudimentary primaries of Stylops.
Pseudo-neurium: a false vein formed by a chitinous thickening of a wing fold.
Pseudo-neuroptera: those net-winged insects with incomplete metamorphosis: includes the present Ephemeroptera, Odonata, Plecoptera, Isoptera and Corrodentia: = Archiptera. ”

“ Now, the majority of the Orthoptera quit the egg in a form which is distinguished from that of the adult Insect almost solely by the want of wings; these larvæ then soon acquire rudiments of wings, which appear more strongly developed after every moult. Even this perfectly gradual transition from the youngest larva to the sexually mature Insect, preserves in a far higher degree the picture of an original mode of development, than does the so-called complete metamorphosis of the Coleoptera, Lepidoptera, or Diptera, with its abruptly separated larva-, pupa- and imago-states. ”

“ Though it generally lives in the water, it sometimes, however, crawls out in good weather; and drying its wings by expanding them in the sun, takes flight, and becomes an inhabitant of the air, not to be known as the same creature, unless to those who had accurately observed it before: when tired of flying, or in danger of an enemy, it immediately plunges into the water. We are told that there are fourteen species of it, seven of which are common in Europe, in waters, &c.
Ephemeral Flies.—This species of insect is named ephemeral, because of its very short existence in the fly state. ”

“ We have seen that the inactive pupa of the male scale-insects is covered by the scale itself, or even in one case the insect forms a true cocoon of fibres of wax. The aquatic 620larvæ of the Neuroptera and Coleoptera creep out of the water, and by the movements of their bodies make a rude earthen cell in the bank, while that of Donacia spins a dense, leathery cocoon (Fig. 567) in the earth. The larvæ of the Embiidæ are protected by a cocoon, which they renew at each moult. Coniopteryx spins an orbicular cocoon, the Hemerobiidæ a spherical, dense, whitish one. ”

“ The fact that in a majority of instances it is possible to trace an intimate connection between the surroundings of a larva and its organization proves in the clearest way that the characters of the majority of existing larval forms of insects have owed their origin to secondary adaptations. A few instances will illustrate this point:—In the simplest types of metamorphosis, e.g. those of the Orthoptera genuina, the larva has precisely the same habits as the adult. We find that a caterpillar form is assumed by phytophagous larvæ amongst the Lepidoptera, Hymenoptera, and Coleoptera. ”

“ This type of insect gradually gave rise to the orders which now contain the largest number of species, including the beetles, moths, and flies. In many lines of this neuropteroid branch, as it is called, the larva has become adapted to a mode of life quite different from that of the adult. Many fly larvae, for example, live in rotting organic material or live as parasites within the tissues of other kinds of insects, whereas the adult flies often feed at flowers on pollen and nectar, visiting the site of the larval habitat only to lay eggs. ”

“ After they become flies, they prey principally on the class of insects termed lepidoptera, and diptera of Linneus. The ephemera is another of this order, which rises from the lakes in such quantities in some countries, that the rustics have carried cart-loads of them to manure their corn lands; the larva swims in the water: in its fly-state the pleasures of life are of short duration, as its marriage, (p. 017) production of its progeny, and funeral, are often celebrated in one day. The phryganea is another fly of this order ”

“ This case-maker is the larva from a fly which bears resemblances to the two families which stand on either side of it—the Lepidoptera, or true butterflies, and the Neuroptera, of which the dragon flies and other membranaceous winged insects are members. As soon as he enters the world, he begins to show his skill in tailoring, and by means of silken threads and gluten constructs his case of bits of stick, straw, dead leaves, or shells, in fact, whatever he can get, and as long as he retains the worm-like form the case is his castle, and he can defy the world. ”

“ A proof that this greater sensibility to modifying causes is not imaginary may, I think, be drawn from the consideration that while the Lepidoptera as a whole are of all insects the least essentially varied in form, structure, or habits, yet in the number of their specific forms they are not much inferior to those orders which range over a much wider field of nature, and exhibit more deeply seated structural modifications. The Lepidoptera are all vegetable-feeders in their larva-state, and suckers of juices or other liquids in their perfect form. ”

“ Considering the parallelism which prevails throughout organic nature between palæontological and embryonic development, it is therefore improbable that the oldest Insects should have possessed fewer segments than some of their descendants. But the larva of the Coleoptera, Lepidoptera, etc., never have more than nine abdominal segments, it is therefore not probable that they represent the original young form of the oldest Insects, and that the Orthoptera, with an abdomen of eleven segments, should have been subsequently developed from them. ”

“ The foregoing brief outline of our knowledge of the geological succession of insects shows that the exopterygote preceded, in time, the endopterygote type of life-history. We have already seen that those insects undergoing little change in the life-cycle, and with visible, external wing-rudiments, are on the whole less specialised in structure than those which pass through a complete transformation. These two considerations, taken together, suggest strongly that in the evolution of the insect class, the simpler life-history preceded the more complex. ”

“ The Campodea-form appears in most of the Pseudoneuroptera [Libellulids, Ephemerids, Perlids, Psocids and Termes] , Orthoptera, Coleoptera, Neuroptera, perhaps modified in the Strepsiptera [Stylops and Xenos] and Coccidæ in their first stage of development, and indeed in many of these at their first moult." Farther on he says, "A larger part of the most highly developed insects assume another larva-form, which appears not only as a later acquisition, through accommodation with certain definite relations, but also arises as such before our eyes. ”

“ The class Coleoptera now approaches the Neuroptera, and on each side the boundary we find larvæ digging pitfalls in the sand to catch their prey, and having tubular mandibles to extract its juices when caught. We find them spinning silken cocoons, in which they change into quiescent pupæ, incapable of taking nutriment; which may fairly be supposed a symptom of approach; but there is no insect whose imago I would venture to place on the circumference of the neuropterous circle at the point. ”

“ Embioptera: an ordinal term proposed for the Neuropterous family Embidae.
Hamabiosis: see symbiosis.
Heliophobic: loving darkness: applied to species that shun the light, like, e.g. Termites.
Heliotactic: light loving: applied to species that live in the open and in daylight.
Lestobiosis: see symbiosis.
Meron: in Neuroptera, a sclerite posterior to the coxa and below the epimeron: corresponds to the trochantine in Lepidoptera.
Metasternal wing: in some aquatic Coleoptera a leaf-like expansion above the coxal plates. ”

“ They appear for a few hours, fluttering about in the rays of a sun whose setting they are not to see, as they live during the space of a single twilight only. These insects have very short antennæ, an imperfect mouth incapable of taking food, and delicate, gauze like wings, the posterior ones of which are always small, or even rudimentary or wanting. Their legs are very delicate--the anterior ones very long--and their abdomen terminates in two or three long articulated filaments. One character, which is unique among insects, is peculiar to Ephemerids ”

“ Into this burrow she pushes a large quantity of spiders, which she has previously captured and paralyzed with her venomous sting. When her nest is properly provisioned she deposits an egg in it, closes the hole with a neat plug of clay, and leaves the larva to quietly consume its half-dead companions. Each female, no doubt, forms a large number of these cells during the summer. While cutting up old logs for Coleoptera, the entomologist will not infrequently come across these nests, when the insects may be found in various stages of development. ”

“ Is there not something more than analogy in the two things, and is not the same life-giving force that evolves a million young Aphides from the germ stock of a single Aphis in a single season, the same in kind with the production of the living races of insects from a primeval ancestor? When we see the Aphis giving origin in one season to successive generations, the individuals of which may be counted by the million, it is no less mysterious than that other succession of forms of insect life which has peopled the globe during the successive chapters of its history. ”

“ This system of classification has therefore been discarded by most entomologists in favour of that based on the difference between those insects which pass through the distinctive stages of caterpillar and chrysalis on the one hand, and those which emerge from the egg as diminutive likenesses of their parents on the other. In this arrangement, the Coleoptera, Hymenoptera, Lepidoptera, Diptera and Neuroptera, fall into the {130}first division, or Heteromorphæ as they are called; and the Hemiptera and Orthoptera into the second or Homomorphæ. ”

“ In all these insects it would be much more convenient to regard the metamorphosis as consisting of only two stages, viz., larva and imago, as there is really no condition analogous to the quiescent pupa of other orders. The female is rather stouter than the male, which is the sex figured, and her abdomen is of a dull bronze colour, instead of metallic blue. ”

“ Their structure and their life-histories entitle them to be ranked as the most abnormal of all Insects, and entomologists are not agreed as to whether they are aberrant Coleoptera or a distinct Order. The newly-hatched larva is a minute triungulin (Fig. 154) , somewhat like that of Meloe; it fixes itself to the skin of the larva of a Hymenopterous Insect, penetrates into the interior, and there undergoes its metamorphoses, the male emerging to enjoy a brief period of an abnormally active, indeed agitated, existence, while the female never moves. ”

“ I wish it to be observed, that Neuroptera, in the genera Psyche, Cloëon, Termes, Psocus and Mantispa, does not merely assume the form of the genera, Tinea, Chironomus, Formica, Aphis and Mantis, but actually possesses the characters and appearance of the classes Lepidoptera, Diptera, Hymenoptera, Hemiptera and Orthoptera. The obviously homogeneous character of Lepidoptera and Coleoptera, although, probably, containing in every sub-class more species than the whole of Neuroptera, clearly disproves the existence of variety amongst their contents, equal to that amongst the contents of Neuroptera. ”

“ Although so very different in general appearance to the preceding insects, this beetle will be found on careful examination to agree with them in all important respects, being only what a ground beetle might naturally become if forced to lead an aquatic existence. Breathing is effected in all the water beetles by the spiracles of the abdomen, which alone are developed. The air is taken in between the elytra and the body, and owing to the convexity of the former, a supply can be retained sufficient to last the insect some twenty or thirty minutes. ”

“ As far as Lepidoptera are concerned, and certain of Hemiptera, they are right—the antennæ in these creatures are the seat of the organs of audition. But in Orthoptera, in most of Coleoptera, Hymenoptera, and Diptera, and in certain bugs (Hemiptera) , they are located elsewhere. The habit that almost all insects have of retracting their antennæ when alarmed by noise, or otherwise, has done much to advance and strengthen the opinion that these appendages are the seat of insect ears ”

“ In the end the insects became, owing to this acquisition of wings, and afterwards to the establishment of a complicated metamorphosis, numerically the most successful type of life in existence, the number of species, extinct and living, mounting into the millions.
All aquatic insects are evidently the descendants of terrestrial forms, and the numberless contrivances and temporary larval organs, particularly of dipterous larvæ, are evidently adaptations to the needs of the insect during its aquatic life, and which are cast aside when the creature passes to a different medium. ”