Our Common Insects Part 3

Our cut (Fig. 28, _a_) also represents the pupa, or chrysalis, as seen lying in its cell. The limbs are folded close to the body in the most compact way possible. On the head of the semi-pupa, _i.e._, a transition state between the larva and pupa, there are two prominent tubercles situated behind the simple eyes, or ocelli; these are deciduous organs, apparently aiding the insect in moving about its cell. They disappear in the mature pupa.

[Ill.u.s.tration: Fig. 29. Fig. 30. Fig. 31.

Fig. 31. Larva of Halictus parallelus.

Fig. 29. Larva of Andrena vicina.

Fig. 30. Pupa of Halictus parallelus seen from beneath.]

To those accustomed to rearing b.u.t.terflies, and seeing the chrysalis at once a.s.suming its perfected shape, after the caterpillar skin is thrown off, it may seem strange to hear one speak of a "half-pupa," and of stages intermediate between the larva and pupa. But the external changes of form, though rapidly pa.s.sed through, consisting apparently of a mere sloughing off of the outer skin, are yet preceded by slow and very gradual alterations of tissues, resulting from the growth of cells. An inner layer of the larva-skin separates from the outer, and, by changes in the form of the muscles, is drawn into different positions, such as is a.s.sumed by the pupa, which thus lies concealed beneath the larva-skin. But a slight alteration is made in the general form of the larva, consisting mostly of an enlargement of the thoracic segments, which is often overlooked, even by the special student, though of great interest to the philosophic naturalist.

From Mr. Emerton's observations we should judge that the pupa state lasted from three to four weeks, as the larvae began to transform the first of August, and appeared during the last week of the same month as perfect bees.

The Andrena is seen as late as the first week in September, and again early in April, about the flowers of the willow. It is one of the largest of its genus and a common species.

Having, in a very fragmentary way, sketched the life history of our Andrena and had some glimpses of its subterranean life, let us now compare with it another genus of solitary bee (Halictus), quite closely allied in all respects, though a little lower in the scale.

The Halictus parallelus excavates cells almost exactly like those of Andrena; but since the bee is smaller, the holes are smaller, though as deep. Mr. Emerton found one nest in a path a foot in depth. Another nest, discovered September 9th, was about six inches deep. The cells are in form like those of Andrena, and like them, are glazed within. The egg is rather slenderer and much curved; in form it is long, cylindrical, obtuse at one end, and much smaller at the other. The larva (Fig. 31) is longer and slenderer, being quite different from the rather broad and flattened larva of Andrena. The body is rather thick behind, but in front tapers slowly towards the head, which is of moderate size. Its body is somewhat tuberculated, the tubercle aiding the grub in moving about its cell. Its length is nearly one-half (.40) of an inch. On the pupa are four quite distinct conical tubercles forming a transverse line just in front of the ocelli; and there are also two larger, longer tubercles, on the outer side of each of which, an ocellus is situated.

Figure 30 represents the pupa seen from beneath.

Search was made on July 16th, where the ground was hard as stone for six inches in depth, below which the soil was soft and fine, and over twenty cells were dug out. "The upper cells contained nearly mature pupae, and the lower ones, larvae of various sizes, the smallest being hardly distinguishable by the naked eye. Each of these small larvae was in a cell by itself, and situated upon a lump of pollen, which was the size and shape of a pea, and was found to lessen in size as the larva grew larger. These young were probably the offspring of several females, as four mature bees were found in the hole." The larva of an English species hatches in ten days after the eggs are laid.

Another brood of bees appeared the middle of September, as on the ninth of that month (1864) Mr. Emerton found several holes of the same species of bee, made in a hard gravel road near the turnpike. When opened, they were found to contain several bees with their young. September 2nd, of this year, the same kind of bee was found in holes, and just ready to leave the cell. It is probable that these bees winter over.

We have incidentally noticed the presence in the nests of Andrena and Halictus of a stranger bee, clad in gay, fantastic hues, which lives a parasitic life on its hosts. This parasitism does not go far enough to cause the death of the host, since we find the young of the parasitic Cuckoo bee, in cells containing the young of the former.

Mr. F. Smith, in his "Catalogue of British Bees," says of this genus: "No one appears to know anything beyond the mere fact of their entering the burrows of Andrenidae and Apidae, except that they are found in the cells of the working bees in their perfect condition: it is most probable that they deposit their eggs on the provision laid up by the working bee, that they close up the cell, and that the working bee, finding an egg deposited, commences a fresh cell for her own progeny."

He has, however, found two specimens of Nomada, s.e.xfasciata in the cells of the long-horned bee, Eucera longicornis. He also states, that while some species are constant in their attacks on certain Halicti and Andrenae, others attack different species of these genera indiscriminately. In like manner another Cuckoo bee (Coelioxys) is parasitic on Megachile and Saropoda; Stelis is a parasite on Osmia, the Mason bee: and Melecta infests the cells of Anthophora.

The observations of Mr. Emerton enable us still further to clear up the history of this obscure visitor. He found both the larva and pupa, as well as the perfect bee, in the cells of both genera; so that either both kinds of bee, when hatched from eggs laid in the same cell, feed on the same pollen ma.s.s, which therefore barely suffices for the nourishment of both; or the hostess, discovering the strange egg laid, cuckoo-like, in her own nest, has the forethought to deposit another ball of pollen to secure the safety of her young.

Is such an act the operation of a blind instinct? Does it not rather ally our little bee with those higher animals which undoubtedly possess a reasoning power? Its _instinct_ teaches it to build cells, and prepare its pollen ma.s.s, and lay an egg thereon. Its _reason_ enables it, in such an instance as this, when the life of the brood is threatened, to guard against any such danger by means to which it does not habitually resort. This instance is paralleled by the case of our common summer Yellow bird, which, on finding an egg of the Cow bunting in its nest, often builds a new nest above it, to the certain destruction of the unwelcome egg in the nest beneath.

In the structure of the bee, and in all its stages of growth, our parasite seems lower in the zoological scale than its host. It is structurally a degraded form of Working-bee, and its position socially is unenviable. It is lazy, not having the provident habits of the Working-bees; it aids not in the least, so far as we know, the cross-fertilization of plants--one great office in the economy of nature which most bees perform,--since it is not a pollen-gatherer, but on the contrary is seemingly a drag and hinderance to the course of nature. But yet nature kindly, and as if by a special interposition, provides for its maintenance, and the humble naturalist can only exclaim, "G.o.d is great, and his ways mysterious," and go on studying and collecting facts, leaving to his successors the more difficult task, but greater joy of discovering the cause and reason of things that are but a puzzle to the philosophers of this day.

The larva of Nomada may be known from those of its host, by its slenderer body and smaller head, while the body is smoother and more cylindrical. Both s.e.xes of Nomada imbricata and N. pulch.e.l.la were found by Mr. Emerton, the former in both the Andrena and Halictus nests, and both were found in a single Andrena nest.

[Ill.u.s.tration: Wood Wasp.]

CHAPTER III.

THE PARASITES OF THE HONEY BEE.

Very few bee-keepers are probably aware how many insect parasites infest the Honey bee. In our own literature we hear almost nothing of this subject, but in Europe much has been written on bee parasites. From Dr.

Edward a.s.smuss' little work on the "Parasites of the Honey Bee," we glean some of the facts now presented, and which cannot fail to interest the general reader as well as the owner of bees.

The study of the habits of animal parasites has of late gained much attention among naturalists, and both the honey and wild bees afford good examples of the singular relation between the host and the parasites which live upon it. Among insects generally, there are certain species which devour the contents of the egg of the victim. Others, and this is the most common mode of parasitism, attack the insect in its larva state; others, in the pupa state, and still others in the perfect, or imago state. Dr. Leidy has shown that the wood-devouring species of beetle, Pa.s.salus cornutus, and some Myriopods, or "thousand legs," are, in some cases, tenanted by myriads of microscopic plants and worms which luxuriate in the alimentary ca.n.a.l, while the "caterpillar-fungus"

attacks sickly caterpillars, filling out their bodies, and sending out shoots into the air, so that the insect looks as if transformed into a vegetable.

The Ichneumon flies, of which there are undoubtedly several thousand species in this country, are the most common insect parasites. Next to these are the different species of Tachina and its allied genera. These, like Ichneumons, live in the bodies of their hosts, consuming the fatty parts, and finis.h.i.+ng their transformations just as the exhausted host is ready to die, issue from their bodies as flies, closely resembling the common housefly.

A small fly has been found in Europe to be the most formidable foe of the hive bee, sometimes producing the well-known disease called "foul-brood," which is a.n.a.logous to the typhus fever of man.

[Ill.u.s.tration: 32. Phora and its Young.]

This fly, belonging to the genus Phora (Fig. 32, Phora incra.s.sata; _a_, larva; _b_, puparium; _c_, another species from Mammoth Cave), is a small insect about a line and a half long, and found in Europe during the summer and autumn flying slowly about flowers and windows, and in the vicinity of beehives. Its white, transparent larva is cylindrical, a little pointed before, but broader behind. The head is small and rounded, with short, three-jointed antennae, and at the posterior end of the body are several slender spines. The puparium, or pupa case, inclosing the delicate chrysalis, is oval, consisting of eight segments, flattened above, with two large spines near the head, and four on the extremity of the body.

When impelled by instinct to provide for the continuance of its species, the Phora enters the beehive and gains admission to a cell, when it bores with its ovipositor through the skin of the bee larva, laying its long oval egg in a horizontal position just under the skin. The embryo of the Phora is already well developed, so that in three hours after the egg is inserted in the body of its unsuspecting and helpless host, the embryo is nearly ready to hatch. In about two hours more it actually breaks off the larger end of the egg-sh.e.l.l and at once begins to eat the fatty tissues of its victim, its posterior half still remaining in the sh.e.l.l. In an hour more, it leaves the egg entirely and buries itself completely in the fatty portion of the young bee.

The maggot moults three times. In twelve hours after the last moult it turns around with its head towards the posterior end of the body of its host, and in another twelve hours, having become full-fed, it bores through the skin of the young, eats its way through the brood-covering of the cell and falls to the bottom of the hive, where it changes to a pupa in the dust and dirt, or else creeps out of the door and transforms in the earth. Twelve days after, the fly appears.

The young bee, emaciated and enfeebled by the attacks of its ravenous parasite, dies, and its decaying body fills the bottom of the cell with a slimy, foul-smelling ma.s.s, called "foul-brood." This gives rise to a miasma which poisons the neighboring brood, until the contagion (for the disease is a.n.a.logous to typhus, jail or s.h.i.+p-fever) spreads through the whole hive, unless promptly checked by removing the cause and thoroughly cleansing the hive.

Foul-brood sometimes attacks our American hives, and, though the cause may not be known, yet from the hints given above we hope to have the history of our species of Phora cleared up, should our disease be found to be sometimes due to the attacks of such a parasitic fly.

[Ill.u.s.tration: 33. Bee Louse and Larva.]

We figure the Bee louse of Europe (Fig. 33 b, Braula caeca), which is a singular wingless spider-like fly, allied to the wingless Sheep tick (Melophagus), the wingless Bat tick (Nycteribia) and the winged Horse fly (Hippobosca). The head is very large, without eyes or ocelli (simple eyes), while the ovate hind-body consists of five segments, and is covered with stiff hairs. It is one-half to two-thirds of a line long.

This spider fly is "pupiparous," that is, the young, of which only a very few are produced, is not born until it has a.s.sumed the pupa state or is just about to do so. The larva (Fig. 33 _a_) is oval, eleven-jointed, and white in color. The very day it is hatched, it sheds its skin and changes to an oval puparium of a dark brown color.

Its habits resemble those of the flea. Indeed, should we compress its body strongly, it would bear a striking resemblance to that insect. It is evidently a connecting link between the flea, and the two winged flies. Like the former it lives on the body of its host, and obtains its food by plunging its stout beak into the bee and sucking its blood.

It has not been noticed in this country, but is liable to be imported on the bodies of Italian bees. Generally, one or two of the Braulas may, on close examination, be detected on the body of the bee; sometimes the poor bees are loaded down by as many as a hundred of these hungry blood-suckers. a.s.smuss recommends rubbing them off with a feather, as the bee goes in and out of the door of its hive.

[Ill.u.s.tration: 34. Hive Trichodes.]

Among the beetles are a few forms occasionally found in bees' nests and also parasitic on the body of the bee. Trichodes apiarius (Fig. 34, _a_, larva; _b_, pupa, front view) has long been known in Europe to attack the young bees. In its perfect, or beetle state it is found on flowers, like our Trichodes Nuttallii, which is commonly found on the Spiraea in August, and which may yet prove to enter our beehives. The larva devours the brood, but with the modern hive its ravages may be readily detected.

[Ill.u.s.tration: 35. Meloe.]

The Oil beetle, Meloe angusticollis (Fig. 35, male, differing from the female by having the antennae as if twisted into a knot; Fig. 36, the active larva found on the body of the bee), is a large dark blue insect found crawling in the gra.s.s in the vicinity of the nests of Andrena, Halictus, and other wild bees in May, and again in August and September. The eggs are laid in a ma.s.s covered with earth at the root of some plant. During April and early in May, when the willows are in blossom, we have found the young recently hatched larvae in considerable abundance creeping briskly over the bees, or with their heads plunged between the segments of the body, greedily sucking in the juices of their host. Those that we saw occurred on the Humble and other wild bees, and on various flies (Syrphus and Muscidae), and there is no reason why they should not infest the Honey bee, which frequents similar flowers, as they are actually known to do in Europe. These larvae are probably hatched out near where the bees hibernate, so as to creep into their bodies before they fly in the spring, as it would be impossible for them to crawl up a willow tree ten feet high or more, their feet being solely adapted for climbing over the hairy body of the bee, which they do not leave until about to undergo their strange and unusual transformations.

[Ill.u.s.tration: Early Stages of Meloe.]

In Europe, a.s.smuss states that on being brought into the nest by the bee, they leave the bee and devour the eggs in the bee cells, and then attack the bee bread. When full-fed and ready to pa.s.s through their transformations to attain the beetle state, instead of at once a.s.suming the pupa and imago forms, as in the Trichodes represented in fig. 34, they pa.s.s through a _hyper-metamorphosis_, as Fabre, a French naturalist, calls it. In other words, the changes in form which are preparatory to a.s.suming the pupa and imago states are more marked and almost coequal with the larva and pupa states, so that the Meloe, instead of pa.s.sing through three states (the egg, larva and pupa), in realty pa.s.ses through these and two others in addition, which are intermediate. The whole subject of the metamorphosis of this beetle needs revision, but Fabre states that the larva, soon after entering the nest of its host, changes its skin and a.s.sumes a second larva form.

Newport, who with Siebold has carefully described the metamorphoses of Meloe, does not mention this stage in its development, which Fabre calls "pseudo-chrysalis." It is motionless, the head is mask-like, without movable appendages, and the feet are represented by six tubercles. This is more properly speaking the semi-pupa, and the mature pupa grows beneath its mask-like form, which is finally moulted. This form, however, according to Fabre, changes its skin and turns into a third larva form (Fig. 37). After some time it a.s.sumes its true pupa form (Fig. 38), and finally moults this skin to appear as a beetle.

Fabre has also, in a lively and well-written account, given a history of Sitaris, a European beetle, somewhat resembling Meloe. He states that Sitaris lays its eggs near the entrance of bees' nests, and at the very moment that the bee lays her egg in the honey cell, the flattened, ovate Sitaris larva drops from the body of the bee upon which it has been living, and feasts upon the contents of the freshly laid egg. After eating this delicate morsel it devours the honey in the cells of the bee and changes into a white, cylindrical, nearly footless grub, and after it is full-fed, and has a.s.sumed a supposed "pupa" state, the skin, without bursting, incloses a kind of hard "pupa" skin, which is very similar in outline to the former larva, within whose skin is found a whitish larva which directly changes into the true pupa. In a succeeding state this pupa in the ordinary way changes to a beetle which belongs to the same group of Coleoptera as Meloe. We cannot but think, from observations made on the humble bee, the wasp, two species of moths and several other insects, that this "hyper-metamorphosis" is not so abnormal a mode of insect metamorphosis as has been supposed, and that the changes of these insects, made beneath the skin of the mature larva before a.s.suming the pupa state, are almost as remarkable as those of Meloe and Sitaris, though less easily observed than they. Several other beetles allied to Meloe are known to be parasitic on wild bees, though the accounts of them are fragmentary.

THE STYLOPS PARASITE.

The history of Stylops, a beetle allied to Meloe, is no less strange than that of Meloe, and is in some respects still more interesting. On June 18th I captured an Andrena vicina which had been "stylopized." On looking at my capture I saw a pale reddish-brown triangular mark on the bee's abdomen; this was the flattened head and thorax of a female Stylops (Fig. 39_a_, position of the female of Stylops, seen in profile in the abdomen of the bee; Fig. 39_b_, the female seen from above. The head and thorax are soldered into a single flattened ma.s.s, the baggy hind-body being greatly enlarged like that of the gravid female of the white ant, and consisting of nine segments).