FIELD BOOK OF INSECTS. 



work with caterpillars which were hatched afield. Plate 

 LXVIII shows Latreillimyia bifasciata and Epalpus sig- 

 niferus; the former is parasitic on various Ceratocampidas. 

 Trichopoda pennipes on the same plate has been bred from 

 the squash-bug, Anasa. Bombyliomyia abrupta (Plate 

 LXVI) is often seen at the edge of woods and in clearings. 

 Williston says: "The habits of the mature fly are 

 similar for nearly all the members of the group. They will 

 be found on vegetation, on leaves or flowers, in such places 

 as are frequented by the hosts which they parasitize. 

 Not a few will be caught with the beating net. . . . The 

 larvas of this group are all parasitic in habit so far as 

 known, and the parasitism is probably confined to the 

 early stages of other insects; and the individual fly is not 

 very particular in the choice of larvas which she parasitizes. 

 Their usefulness in keeping injurious insects in check is 

 immeasurable. By far the largest number of species are 

 parasitic upon Lepidoptera, of which not less than four 

 hundred have been recorded [many more now]. About 

 seventy species are known to be parasitic upon Hymen- 

 optera, less than forty upon Coleoptera, a score upon 

 Orthoptera, five upon Hemiptera, and as many upon 

 other Diptera." 



SARCOPHAGID.E 



These are popularly called Flesh Flies. The family 

 may be fairly well recognized by the key given on p. 258. 

 To be perfectly frank, I dislike writing about unclean 

 things and will use a short service with this family; be- 

 sides it is a very difficult group, taxonomically. The 

 Thomas Say Foundation, care of the Academy of Natural 

 Sciences of Philadelphia, has just published a monograph 

 of the family by J. M. Aldrich. It is claimed that 20,000 

 eggs have been found in the ovaries of a single Sarcophagid. 

 The principal genus is Sarcopliaga (see Plate LXX). 

 Although most of the Sarcophagidas justify their scientific 

 name and its English equivalent, the larvas of others 

 feed on dung and rotting vegetable material. Some 

 larvas are found under the skin of turtles, others in the 

 stomachs of frogs; while still others are parasitic in snails 



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