CLASSIFICATION AND DESCRIPTION OF COMMON INSECTS 271 



and may lay several times; hatch in about 8 hours in mid-summer. 

 Laid in horse manure, pig manure, and to a less extent in other manure, 

 human excreta, in decaying grain, moist bran, moist mixtures of hay 

 and grain from feed troughs, in excreta-soiled straw, decaying kitchen 

 refuse, rotting fruits, vegetables, in ensilage. 



Fig. i73.^The common house-fly (Musca doynesticd) . Puparium at left; adult next; 

 larva and enlarged parts at right. All enlarged. {After Howard.) 



Larva. — At first glistening white; two moults; duration about 5 days; 

 yellowish when full grown, slender in front and truncate behind; a 

 large hook above the mouth; active. Develops in horse manure 

 and other filth in substances more or less alkaline. ^ 



Pupa. — ^Puparium nearly cylindrical, 

 dark chestnut; duration 3-4 days. 



Duration of Hfe-cycle 10-14 days. Prob- 

 ably seven to ten generations develop be- 

 tween April 15th and October loth. It 

 hibernates as larva or pupa in the South 

 but probably more commonly as adult in 

 the North. (Consult Howard's and 

 Hewitt's books on "House Flies.") 



Stable Fly {Stomoxys calcitrans Linn.). 

 — Occurs in stables, yards, shady groves, dwellings, etc. 



Adult. — Resembles house-fly, but has piercing mouth-parts; bright 

 golden tinge at front end of median, light stripe on thorax; six black lines 

 on thorax; dorsal surface of abdomen with a number of nearly round 

 dark spots. Bite severe but not poisonous. A carrier of disease; 

 breeds in moist straw and hay. 



P e 



Fig. 174. — Extremity of 

 tarsus: e., empodium; p., 

 pulvillus in A, Bibio; B, 

 Musca. 



