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Thursday, April 30, 2009
Bees
The True Bees (Super-family Apoidea)This great group, comprising about five thousand species, includes all of the true bees, both the honey-gatherers which have social communities and live a strict community life, and the solitary bees. The hind feet of these insects are dilated or thickened, and that the hairs of the head and thorax are feathery. These peculiar Feathery hairs are found only in the true bees, which also differ from other Hymenoptera by the peculiar modification of the mouth-parts which are lengthened into a structure which is almost like a proboscis. It is a very conspicuous organ and is fitted in many of them for probing deep flowers and for gathering nectar. The mandibles or upper jaws play no part in this proboscis-like structure, which is composed entirely of lower lip and lower jaws, both greatly lengthened. The eggs of all bees are laid in cells of one kind or another in which the larva develop. Sometimes they are fed by the adult bees and sometimes a supply of food is stored in the cell so that after the egg is laid and the cell is completely closed the mother has no more responsibilty for the growth and development of her offspring.It is among the higher and more specialized bees that we see for the first time the extraordinary community life which is developed among them and certain other Hymenoptera, such as certain social wasps and ants, and practically nowhere else, except among the so-called white ants or Termites, which belong to quite a different order. With the social bees we find a most perfect communism ; each individual works for the good of the community, and thus only indirectly for its own ends.In the evolution of this community life strange things have happened. There has come to be a class of individuals which are practically sexless, and are called neuters or workers. These individuals do the mechanical work of the community. They are really structurally females in which the development of the sexual organs has ceased at a certain point. They are undeveloped and infertile females. The other two sexes are represented, but the number of true females, or queens as they are called, is small, only a sufficient number being found to supply eggs for the perpetuation of the community. The males are aptly termed drones, since they are drones in comparison with the active and hard-working neuters or workers. Their function in the community is simply to fertilize the queens at the proper time, and then they are of no further use in the world.The Apoidea are now subdivided into no less than fourteen fullfledged families. These include the Apidae, or true honey bees, the Bombidae, or bumblebees, the solitary bees of the Anthophoridae, the cuckoo bees of the family Nomadidae, the small carpenter bees of the family Ceratinidae, the large carpenter bees of the family Xylocopidae, the mason, leaf-cutting and potter bees of the family Megachilidae, the parasitic bees of the family Stelidae, the sharp-tongued burrowing bees of the family Andrenidae; the blunt-tongued burrowing bees of the family Colletidae, and others.The habits of the bees of these diverse families vary greatly, and most of the characteristics which they have in common have already been referred to. All, from their flower-visiting habits, are of great importance in the cross fertilization of plants, and without their aid the health of the plant world would suffer and its infinite variety would hardly have been achieved.The most famous of all bees is naturally the common honey bee, an importation from Europe, not a native, which by the hand of man has become a true domesticated animal. The life history of this creature has been so often written about and may so easily be learned by consulting any encyclopedia or standard general work of reference that it does not seem necessary to describe it in detail here. The methods of bee culture in use admit of ready study of its economy. In this brief summary of the general characteristics of bees we shall, therefore, confine ourselves to the wild and less known forms. A bumblebee has been selected for the typical life history, and little need therefore be said of the large and important family to which that species belongs, except to state that bumblebees now occur in most parts of the world, and that they are especially abundant in temperate and even boreal regions, large numbers inhabiting far northern localities where they abound in the brief artic summer, and where they live a short but extremely busy life on account of the crowding together of the flowering periods of sub-polar plants.The solitary bees of the family Anthophoridae are in general thickly clothed with hair, and many of them burrow into the earth, forming tunnels in which they form earthern cells, staring them with a supply of pollen and honey upon which the egg is laid and the cell is then closed. Much good work can be done in the way of accurate observation upon the members of this group ; the length of the larval life, duration of the egg stage, and other points have not been accurately followed out, although some of the European species are fairly well known. Certain species bore into wood instead of entering the earth, or they occupy old burrows of some carpenter bee. There are certain curious parasites Of these bees, and the life of one of them has been studied by the English observer Newport.The cuckoo bees of the family Nomadidae without exception live parasitically in the nest of other bees, and have undoubtedly originated from other bees through different lines of descent - probably from those of the group just mentioned. As their parasitic habits would prepare us to learn, their legs are without the scopa for the carriage of pollen, and their life is practically that of the cuckoo, the female laying her eggs in cells already prepared by some more industrious and conscientious bee, and her larva living at the expense of the offspring of the cell - Curiously enough, these bees seem to be on perfectly good terms with their hosts, visiting flowers in their company and visiting their burrows as unconcernedly as though they were the result of their own labors. Emerton has observed that there is frequently enough food for the larva of the cell-maker and the larva of the cuckoo bee, and that they both thrive and issue as adults simultaneously. This cuckoo life is found with bees of certain other groups, and will be referred to later.The rather smooth and active little bees of the family Ceratinidae, which have been termed small carpenter bees, are extremely interesting creatures, and are generally metallic blue, blue-black or bright green four-winged flies, not hairy, and are very active in the summer time. They bore tunnels into the stems of pithy plants and form their cells in these burrows. They are very commonly found in brambles. The cells are lined with a delicate silky membrane and are separated from one another by mud partitions. The common Ceratina dupla is a familiar example. With this bee the cells are filled with a paste of honey and pollen upon which the larvae feed. The transformation to imago occurs in the latter part of July or during August. From the cells of this bee two very remarkable parasites have been reared by the Rev. J. L. Zabriskie, namely Diamorus zabriskii Cres., and Axima zabriskii How.The large carpenter bees, however, do not confine themselves to the stems of plants. Their burrows are so large that they are frequently made in the dead trunks of old trees and commonly in lumber, and even in the joists of buildings. The commonest of the large carpenter bees in this country is Xylocopa virginica. This large black-bodied bee, as big as the biggest bumblebee, but with a flatter and less hairy abdomen, bores symmetrical tunnels into solid wood, choosing in civilized regions fence posts and boards. The burrow is a half-inch in diameter, and runs horizontally across the grain for about the length of the insect's body, and is then turned downward at right angles and runs with the grain from twelve to eighteen inches.In this boring the bee progresses at the average rate of about half an inch a day, occupying at least two days in digging the first portion against the grain of the wood. After the burrow is once commenced, their persistence in returning to continue the work, in spite of all obstacles, is very remarkable. One of these indefatigable bees once started a burrow in a lintel over the front door of the writer's house in Georgetown. She was repeatedly driven away, was struck with a broom a number of times, and finally ceased from her labors only because kerosene was squirted at her through a syringe with accurate aim. It was the hand of death alone which released her from her work. The tunnels generally run in opposite directions from the opening, and sometimes other galleries are made, one parallel with the other, using a common opening. While we may admire the industry of the carpenter bee in doing all this hard work for its young, it is not averse to an easy thing, and will use the same burrow over again, and if an old deserted burrow can be found which was made the previous summer, or even several years previously, it is preferred to the drudgery of making a new one. Moreover, there are other bees which will pre-empt the deserted burrows of the carpenter bees.After the tunnels are prepared the cells are made and supplied with pollen. With the species under consideration the cells are about seven-tenths of an inch long, and are separated from each other by partitions which are made up of a single flattened band of sawdust and fine chips glued together and rolled up into a flat partition about four layers deep. The side forming the bottom of the cell is concave and smooth, while the other side is flat and rough. Even about the common carpenter bee there is much yet to be learned, and a careful series of studies carried through an entire season cannot fail to show novel facts.The mason bees of the family Megachilidae (sub-family Osmiinae) derive their name frem the manner in which they construct small earthen cells under stones, in the burrows of other bees, in decaying wood, in deserted snail shells, in old galls, and elsewhere. These bees show a great diversity of habit. Their cells are constructed of sand, earth or clay mixed with pebbles and wood scrapings, but glued together so firmly that they are smooth inside. Ten to twenty of them are usually found together, and each one contains a store of honey and pollen, for the larvae, of which only one is found in each cell. One of these bees (Ceratosmia (Osmia) lignivora Packard) has been shown by Dr. Packard to be a true wood-borer. He saw it make a tunnel three inches long in maple wood, the tunnel containing five cells and the partitions being made of wood chippings. The leaf-cutting bees of the same family are common creatures whose habits are extremely interesting. They derive their name from the fact that they cut pieces out of the tender leaves of various trees with which to form their cells.
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