206 OUR HOUSEHOLD INSECTS 



As the pupae of these insects are formed underground, 

 no doubt in the above instance members of the autumn 

 brood survived the winter in the pupa condition, and 

 the ravagers of the second year were the offspring of 

 these ; hence the advisability, apart from any other 

 reasons, of not sowing onions two years in succession 

 on the same ground. As many of the Muscidce are 

 destructive to living plants, their larvae either forming 

 galls, mining in the leaves, or causing, as in the instance 

 quoted, a rottenness of the part affected, there is nothing 

 unusual in the above occurrence, except that an insect 

 which is generally credited with being a dung-feeder 

 should unite with such habits that of feeding upon living 

 plants. But a much more remarkable change of diet 

 has been recorded of the same insect. It has been 

 found by Professor Biley to be an internal parasite of 

 the so-called cotton-worm of America, its maggots feed- 

 ing upon the viscera of the insect in the same way as 

 those of the ichneumon flies. Such parasitism again is 

 a habit of other Muscidce, and the peculiarity in the 

 present case consists simply in the abandonment of a 

 vegetable for an animal diet, for which it is difficult to 

 conceive the inducement. 



By far the handsomest of all our household Diptera is 

 the greenbottle, which, though extremely abundant out 

 of doors, is only an occasional visitant indoors; it is, 

 however, closely associated with man and his surround- 

 ings. Its body is of a most brilliant metallic golden - 

 green colour, whence its popular name. Its scientific 

 name is Lucilia Coesar; its habits are similar to those 

 of Calliphora. It attacks meat, but is more frequently 

 seen on raw flesh than on cooked, and preferably sucks 

 that in which decomposition has already set in. It is 

 a great pest to fishmongers, and a piece of stale fish 



