INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



329 



TACHINID^ (Family) 



THE TACHINA FLIES 



This is one of the most beneficial families of insects, because of the 

 parasitic habits of the larvae upon destructive caterpillars, grass- 

 hoppers, bugs, beetles, sawflies, etc. 



The adults vary greatly in size and are usually grayish with striped 

 and very hairy bodies. They become very active on hot days. The 

 eggs arc usually white and stuck to the living larva 1 , upon which the 

 maggots are to feed. Upon hatching, the larva 1 bore through the skin 

 of the host, nourishing themselves throughout their development upon 

 the internal tissues, avoiding the destruction of the vital organs until 

 ready to pupate. When the host is destroyed they usually leave the 

 old carcass and form hard, brown puparia near the surface of the 

 ground. The adults issue from these in a very short time. Breeding 



Fig-. 323. — A tachina fly, Phorocera saundersii Willtoton 

 reared from caterpillars of the variegated cutworm, Men- 

 docino County, Sept. 14, 1914. The flies are dark allic 



blue; the females averaging ; inch and the males 3-16 inch 

 in length. The specimens were determined by W. R. Walton 

 through the kindness of Prof. J. M. Aldrich. (Original) 



is rapid, there being, in some species, several generations cadi year. 

 The reproductive habits are varied. Some lay large, flat, whitish 

 cogs on the host, the larvae emerging below and entering the host 

 without disturbing the empty egg-shell; others lay Large numbers of 

 minute eggs on the foliage, which are swallowed with the plant 

 tissues by the host in feeding; still others puncture the integument 



