PARASITES OF FLIES 235 



household cheese-, ham- and flour-mites" (Howard, 1911, 

 p. 75). Flies are, therefore, probably agents of some importance 

 in spreading mites destructive to certain foods. 



" Flies emerging from pupae in a rubbish heap or hot-bed 

 will frequently be found to be carrying numerous small brownish 

 mites. Many of these belong to a group Ganmsidce which are 

 rather flat and broad mites, and their larvse occur in large 

 numbers in such situations as rubbish heaps, etc. To these 

 immature forms the fly serves as a most convenient transporting 

 agent and assists in the emigration of the mites to new fields. 

 Some of these forms are parasitic, as I have found them firmly 

 attached by their mouth parts to the under-sides of flies" 

 (Fig. 26) (Hewitt, 191 2, p. 60). 



Fig. 27. Chelifer, Cheriies nodosus. 



False-scorpion. Chernes nodosiis Schrank. 



Small reddish scorpion-like creatures, often called CJielifers, 

 belonging to the order Pseudo-scorpiouidca, are frequently found 

 attached to the legs of flies, the most common species being 

 C. nodosus. This creature, which is about 2*5 mm. in length, 

 possesses four pairs of legs, and a pair of large pincer-like append- 

 ages with which it clings firmly to the fly. It is reddish-brown 

 in colour. The head and thorax are united in a single segment, 

 and the abdomen is clothed with a large number of hairs. It 

 commonly lives among refuse such as decaying vegetation, 



