. An introduction to zoology, with directions for practical work (invertebrates). INSECT A : DIPTERA 333 Volucella. then separating from its skin, -which forms a rather pear- shaped white case round the body, -which is transformed -within. The fly emerges in about ton days; it is at first small -with tightly crumpled-up wings, but in a quarter of an hour it attains its final state. Volucella is another common species of Syrphid. It lays its eggs inside the nests of humble-bees or wasps, and it used to be thought that the larva fed on the young bee and wasp larvae. Recent investigations, howeve
. An introduction to zoology, with directions for practical work (invertebrates). INSECT A : DIPTERA 333 Volucella. then separating from its skin, -which forms a rather pear- shaped white case round the body, -which is transformed -within. The fly emerges in about ton days; it is at first small -with tightly crumpled-up wings, but in a quarter of an hour it attains its final state. Volucella is another common species of Syrphid. It lays its eggs inside the nests of humble-bees or wasps, and it used to be thought that the larva fed on the young bee and wasp larvae. Recent investigations, however, seem to show that this is not so, but that the Volucella larvae are useful to their hosts, for they act as scavengers, feeding on the waste matter and dirt of the hive. Eristalis £ristalis, another tenaz (the member of the Syr- Drone-fly). phidae, is peculiar in having an aquatic larva of a very interesting and unusual type. This black, hairy " Drone-fly " is rather bee-like in form; it is a strong, active fly, a little over ^ an inch long. It lives on the honey and pollen of flowers, quit- ting, however, the fresh sunny garden, to lay its little packets of white eggs on the surface of the dirtiest, most putrid water it can find, often in a manure tank. The larva, when it hatches out, spends its time creeping over the mud and debris at the bottom, feeding on the decaying organic matter, but always keeping up communication with the air above the water, by means of the curious telescopic tail through which it breathes. This stage is a strange contrast to its later life, when it flies freely in a garden, and we are perhaps inclined to think of it as an undesirable inhabitant of our tanks, though, as a matter of fact, it lessens rather than increases the putrid condition of the water by. Fig. 253.—Jiristalis tenax. E, Eggs; L, larvae, " rat-tailed mag- gots " of two ages, one crawling on the mnd, the other suspended from the Please note that thes
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Keywords: ., bookcentury1900, bookdecade1910, bookpublisherlondo, bookyear1913
