FIELD BOOK OF INSECTS. 



The sides of the abdomen of the males are brownish near 

 the base and grayish elsewhere. The females are grayish 

 over all the abdomen with a variable pattern of darker 

 gray or black. It takes the egg about twelve hours, 

 on the average, to hatch. In about five days the larvae 

 are full-grown and the pupal stage lasts from five days to a 

 month or longer. The puparium is the old larval skin, 

 hardened and brown. Each female usually lays from one 

 to two hundred eggs in the garbage or manure which is the 

 food of the larvae. Adults may hibernate, but so also do 

 pupae and larvae. See Homatomyia. 



Pseudopyrellia ctzsarion (Plate LXIX) is easily recog- 

 nized by the characters given in the key, especially those 

 in couplet 12. The brilliant blue larvae are often abundant 

 in cow dung. 



Other flies besides Calliphora "blow," 

 Calliphora . 



that is, lay eggs on meat, but the name 



Blow-fly is usually applied to members of this genus. 

 The anatomy, physiology, and development of C. ery- 

 throcephala are very well known, thanks to Lowne's classic 

 work and Portchinski's careful observations. The other 

 two species (see the key and Plate LXX) probably differ 

 but little from it. It lays several hundred small eggs 

 on meat and dead animals. These eggs hatch in about 

 twenty-four hours or less, sometimes even hatching in the 

 female, so that she lays living larvae. It takes a week or 

 ten days to reach the pupal stage and then about two weeks 

 for adults to emerge. The mature larva may be nearly 

 or quite .75 in. long. Pupation usually takes place under 

 the food-mass or slightly below the surface of the ground. 

 All three species occur also in Europe. 



L. sylvarnm is the bluest Blue-bottle; 

 ccEsar (Plate LXX) is more often greenish; 

 and sericata usually has a bronzy gleam, especially on the 

 abdomen. See also Phormia, p. 273. Carrion is their 

 chief larval food but L. casar has been reared from excre- 

 ment and garbage. The life-histories-are completed in 

 from three to four weeks and are abfoat sgqually divided 

 between larval and pupal stages. 



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