iiioiv ahiiiulant of later years. It l)reeds in the dust under cariK'ts. 

 and its larva is a white, very slender, almost threaddikf crenttire. 



Not much complaint would be made of house flies were the true 

 house fly a nonexistent form. Under ordinary circumstances it far 

 outnumbers all other species in houses. Connnon and widespread as 

 this species is, there is very general ignorance, as with many other 

 extremely connnon insects, as to its life history and habits outside 

 of the adult stage. Writing in IST:'), Dr. A. S. Packard ^ showcMl 

 that no one in this country had up to that time investigated its habits, 

 and that even in Europe but little attention had been given to it. He 

 showed that the habits were mentioned in only three w^orks, one of 

 Avhicli was published during the ]H'esent century, with figures so 

 poor and inadequate as to be 

 actually misleading. De Geer 

 (lTr)2) showed that the larva 

 lives in warm and humid dung, 

 but did not say how long it re- 

 mains in the ditferent stages. 

 Bouche (1S;U) -tates that the 

 larva lives in horse and fowl's 

 dung, especially when warm. 

 Tie did not, however, give the 

 length of the larval state. 



Dr. Packard studied the spe- 

 cies Avith some care, and ob- 

 tained larse numbers of the 



a, J, 



KiG. 3.— The common house lly; ■(, piipa removed 



ea'Ji'S bv eXi:)OSino' horse manure. fn)m puparium; b, hind eml of body of larva msec- 

 "^ ■ ,. 11 /• iV 1,1 , Olid stage; c, anal spiracles of larva m fir^5t stage- 



He carefully followed the trans- all enlarged (author's illustration). 



formations of the insect, and 



gave descriptions of all stages. He found the duration of the egg- 

 state to be twenty-four hours, the duration of the larval state five to 

 seven days, and of the pupal state five to seven days. The period 

 from the time of hatching to the exclusion of the adult therefore 

 occupies, according to Packard, from ten to fourteen days. His 

 observations were made at Salem, Mass. 



As is quite to be expected, as we go farther south, the house fly 

 becomes more numerous and more troublesome. The number of gen- 

 erations annually increases as tlie season becomes longer, and Avith the 

 warm climate the development of the larva^ becomes more rapid. A 

 few rearing experiments were made in this office during the summer 

 of 181)5, and it was unexpectedly found that the house fly is a dillicuh 

 insect to rear in confinement. Buzzing about everyAvhere, and ai)|):ir- 

 entlv liviuii- with ease under the most adverse conditions, it is ne\-er- 



' On the Transformation of the Common House Fly, with Notes on Allied Forms. 

 Pi-oc. iioston Snc. .Nat. Hist., A'ol. XVI, 1874, p. loG. 

 ICir. :55] 



