Parthenogenesis, in the production of males, has also been found by Siebold to be true of other bees and wasps, and of some of the lower moths, in the production of both males and females. While the great Bonnet first discovered what may be noticed on any summer day, all about us, even on the house-plants at our very windows, that parthenogenesis is best illustrated by the aphides or plant lice. In the fall males and females appear, which mate, when the female lays eggs, which in the spring produce only females; these again produce only females, and thus on, for several generations, till with the cold of autumn come again the males and females. Bonnet observed seven successive generations of productive virgins. Duval noted nine generations in seven months, while Kyber observed production exclusively by parthenogenesis in a heated room for four years. So, we see, that this strange and almost incredible method of increase, is not rare in the great insect world. About two days after she is impregnated, the queen, under normal circumstances, commences to lay, usually worker-eggs, and as the condition of the hive seldom impels to swarming the same summer, so that no drones are required, she usually lays no others the first season. It is frequently noticed that the young queen at first lays quite a number of drone-eggs. Queen-breeders often observe this in their nuclei. This continues for only a few days. This does not seem strange. The act of forcing the sperm-cells from the spermatheca is muscular and voluntary, and that these muscles should not always act promptly at first, is not strange, nor is it unprecedented. Mr. Wagner suggested that the size of the cell determined the sex, as in the small cells the pressure on the abdomen forced the fluid from the spermatheca. Mr. Quinby also favored this view. I greatly question this theory. All observing apiarists have known eggs to be laid in worker-cells, ere the cell was hardly commenced, when there could be no pressure. In case of queen-cells, too, if the queen does lay the eggs--as I believe--these would be unimpregnated, as the cell is very large. I know the queen sometimes passes from drone to worker-cells very abruptly while laying, as I have witnessed such a procedure--the same that so greatly rejoiced the late Baron of Berlepsch, after weary hours of watching--but that she can thus control at the instant this process of adding or withholding the sperm-cells, certainly seems not so strange as that the spermatheca, hardly bigger than a pin-head, could supply these cells for months, yes, and for years. Who that has seen the bot-fly dart against the horse's legs, and as surely leave the tiny yellow egg, can doubt but that insects possess very sensitive oviducts, and can extrude the minute eggs just at pleasure. That a queen may force single eggs, at will, past the mouth of the spermatheca, and at the same time add or withhold the sperm-cells, is, I think, without question, true.