-^^ THE VOLUCELLAL. 399 



evidently a change has taken place, for the larval condition is at 

 an end. If one of these floating creatures be taken up and cut 

 open, the pupa will be seen within the skin, which acts as the 

 cocoon, and also as a boat for the fly which will spring into life 

 in a short time. The fly, which has two perfect wings, a flat body, 

 long antennae, and which is decorated with beautiful colours, is about 

 as different an insect from the long-tailed, dull-coloured swimming 

 larvae as can well be imagined. In the engraving opposite the 

 perfect insects are seen in flight, and one is upon a rush ; two larvae 

 are shown, one on the right hand side has its tail erect, and is 

 breathing in air, and beneath the insect on the leaf, is a nymph. 



The Diptera with a short and thick trunk, mandibles united 

 to form a single blade, and with a broad and very flexible lip, 

 which makes a good sucker, are distinguished as SyrpJiidcs. 

 Their proboscis is thus long and membranous, and they like 

 honey. There are several very interesting genera in this family. 

 The VolucellcB are large flies, which have black, yellow, and 

 russet colours upon them, and they choose the nests of social 

 bees for their larvae. The female deposits its eggs in the combs, 

 and particular species have their favourite bee-hive or wasp nest, 

 as the case may be. Thus Voliicella bonibylmis visits the humble 

 bees, and Vohicella zonaria attacks the wasps, and curiously 

 enough wears the livery of those dangerous insects, amongst 

 which she leaves her eggs. The larvae of Vohicella are of a dirty 

 white colour, are covered with small spines, and the last segment 

 of the body is rounded off", and is pierced for the organs of 

 respiration. The membranous legs are furnished with little hooks. 

 The &^^ is laid in the cell which contains the wasp larva, and 

 when it is hatched the Vohicella eats its way into its victim, and 

 gradually intrudes the whole of its body except the last segment, 

 which being in contact with the. external air, and having the respi- 

 ratory orifices in it, is the only portion of the body by which the 

 parasite can be distinguished, and through which it can take in 

 air to oxygenate its blood. 



When the Vohicella larvae attain their full growth they are 

 transformed into nymphs, which have two small open tubes placed 

 upon the prothoracic region, and which communicate internally 

 with the tracheae. This apparatus is like that of the gnat. 



