504 THE INSECT WORLD. 



the type. Secondly, Elenchus^ of which Elenchus Walkeri is the 

 type. Thirdly, Sty lops (Fig. 543), parasitical on various species of 

 AndrencBf of which Stylops Melittm, having a fleshy abdomen and the 

 wings longer than the body, may be con- 

 sidered typical : and lastly, Halidophagus^ 

 of which only one species, infesting Halidus 

 (ie?'atus,^'' named Halictophagiis Ctirlisii, is 

 known to exist, and which makes its ap- 

 pearance in the month of August. 



These singular insects are found in 



various parts of the world — Europe, Aus- 



Fig. 543.-Styiops (magnified). ixdi\\2i, and America. They were discovered 



by Professor Peck almost simultaneously 



with Mr. Kirby's discovery in this country, and to whom he sent 



specimens of a species which has received the name of Xenos Peckii 



lately, in New Zealand and elsewhere. 



Siebold, in 1843, having obtained some eggs, was able to observe 

 the larvae, and he soon discovered that the females of Stylops, one 

 of the Strepsiptera, were blind, had no legs, and always retained the 

 appearance of larvae, and that they never quitted the bodies of those 

 insects, in which they pass a parasitic existence. George Newport 

 paid great attention to the history of these curious insects, and when 

 he wrote his article, " Insecta," in the "Cyclopaedia of Anatomy and 

 Physiology," four distinct genera of these minute parasites had already 

 been discovered. One of the largest species (Stylops Spencii) is 

 scarcely more than two lines in length, while the smallest species yet 

 known is not more than two-thirds of a line, or scarcely a line in 

 breadth with its wings expanded. They undergo metamorphosis ; 

 and the males, when they have become perfect insects, fly and roam 

 about, but the females are condemned to a perfectly quiet life. The 

 head and the thoracic segments of the bodies of these last are united 

 completely, but the abdomen, which is very large, always remains 

 soft, so that the whole of the body only appears to be formed of 

 two portions. They are ovo-viviparous insects, and the young larvae 

 escape as such from the body of the mother. They are active 

 creatures, and, being furnished with long legs, crawl over the hairs 

 and skin of the hymenopterous insect they are parasitic upon. They 

 behave like the larvae of Meloe and Sitaris, whose peculiar methods 

 of life have been noticed in our description of the Coleoptera. 

 Clinging on to a wasp or a bee, they are carried off, and finally 



* Halictus and Andrena are two genera of Bees. 



