424 



NATURAL HISTORY OF ARTHROPODS. 



Fig. 631. — Lai'va pupi- 

 gera of EHstalis. 



Fig. 532. — Syrphus 7neso~ 

 grapta polituSf enlarged. 



Pacific. The larvae, as in MaUota and some other species of the family, are very 

 curious creatures. They are ovate in shape, somewhat elongate, with seven pairs of 

 abdominal legs below, each of which terminates in a booklet ; posteriorly they end 

 in a long, slender tail, composed of two joints, the last of which 

 slides within the preceding one like the joints of a telescope. 

 This curious organ enables them to breathe from the surface 

 while lying snugly concealed in mud or in outhouses, where 

 they feed upon decaying vegetable or excrementitious matters. 

 This peculiarity of structure has given them the name of " rat- 

 tailed larvae." Their skins are very tough, whence comes the designation of tenax. 

 The pupal envelope of the rat-tailed larvae is ellipsoidal in shape, with the tail bent 

 over the body. 



Interesting also are the habits of members of the genus Syrphus, of which there 

 are about twenty-five North American species. The flies are usually less than a haK 

 inch in length, very prettily banded with yellow, and, like man}' 

 others of the family, are remarkable for their rapid motions in the 

 air, and the ease with which they hover over flowers. The larvae 

 are cylindrical maggots, without a head, and the mouth-parts 

 consisting of from two to four outwardly-bent booklets. The 

 eggs are deposited by the female upon plants infested by plant- 

 lice. The young larvae as soon as hatched crawl over the stems 

 and leaves till they come in contact with the Aphides, which 

 they pierce with the booklets and, holding aloft, suck out their 

 juices, to the number of a hundred or jnore daily. When ready 

 to undergo their transformations they attach themselves to the leaves, and the larval 

 skin contracting forms an oval puparium or larva pupigera. 



Another interesting group in their early forms are the species of Microdon. The flies 



are usually dull colored, rather slow 

 in flight, and found on borders of low 

 woodlands. They can generally be 

 recognized by the presence of a pair 

 of spines on the scutellum, and by 

 their antennae being elongated. The 



Fig. 633. -Microdo™ globosus: a, larva just before pupation; Jarvas shoW a Strange resemblance tO 

 b, front view of pupa case ; c, larva pupigera. , o 



certain shells, so much indeed that 

 twice have they been described and named as species of molluscs! 



The larvae of Baccha, Sjyhoerophoria, Pipiza, and 

 Paragus are also known to feed upon plant-lice. The 

 larvae of many species live in decaying wood, in the 

 stems and bulbs of plants, under bark, in water, and 

 about ants' nests, all of which are characterized by the 

 stigmata being confined to a single or double breathing- 

 tube of variable length at the hind end of the body. 



Mallota posticata, here figured, is black, thickly 

 covered with black and yellow pile; the larvae and ma. 63i. — Maiiota posticata -, 

 pupae are found in old trees. Pipiza radicum is a "' "™ p^'P's^''*'- 



small fly of a uniform dark metallic color ; its larva lives underground, and feeds upon 

 the apple-root lice {ISriosoma pyri) and the grape-root lice {Phylloxera radicola). 



