FIELD BOOK OF INSECTS. 



Plate LXIX. The squamae are slightly 

 Graphomyia dusky. Some, at least, American speci- 



maculata 



mens lack the yellowish color which has 

 been recorded for the European ones on the scutellum. 

 The larvae are said to live in excrement. 



This species (Plate LXX) varies from 

 Chrysomyia to { ^ {n length> The norma l 



macellana ^ ~ . . 



lood 01 the larvas is carrion. Pupation 



usually occurs in earth or moist debris. The mature 

 larva is .75 in. long and is provided with a ring of bristles 

 between each pair of segments. These and its pointed 

 shape make it somewhat resemble a screw, hence the 

 common name, Screw T -worm. They occasionally feed on 

 living animals, including man, the eggs being laid in open 

 wounds or in the nose. In the latter case, the larvae work 

 their way into the cavities of the head and sometimes 

 cause death. 



Adults (Plate LXIX) range from .25 to 

 Cynomyia - Q in> in i engt h. T h e thorax is slaty-black, 



cadaverina . . 



with indistinct stripes on the antenor 



portion. It is very difficult to cite good characters for 

 separating this insect from Calliphora. However, common 

 species of Calliphora do not usually have markings on the 

 thorax; if they have, the markings are indistinct and not 

 as described for this species. Furthermore, the buccas 

 of cadaverina are grayish-black posteriorly and brown to 

 reddish anteriorly; those of Calliphora are usually uni- 

 colorous. Although the adults are captured about excre- 

 ment, it is probable that the larvae feed exclusively on 

 decaying flesh. 



Plate LXIX. The squamae are yellowish. 

 Myospila The larvg liye in excrement . Only a few 



meditabunda . , , , 1 



(several dozen) eggs are laid by each female. 



The eggs have a black stripe on each side and, as continua- 

 tions of these, a black curved appendage. This fly is 

 common to both Europe and America. 



270 



