Parasites, Diseases and Enemies. 281 



hour. This dragon-fly (Libellulida) is also called darn- 

 ing needle, mosquito-hawk and demoiselle. Perhaps 

 the adult insect has its uses, but the fishculturist has 

 no use for it. 



The great larva of the helgramite fly (Corydalus cor- 

 nutus) may kill some fish, but if it does I don't know it. 

 This larva is two and one-half inches long, and has a 

 powerful pair of pincers; it lives in brooks, under 

 stones, and crawls ashore to enter the pupa stage under 

 logs. The great insects fly by night and are seldom 

 seen; the larva is a famous bait for black bass, and is 

 called dobson, crawler, kill-devil, and about twenty 



HELGRAMITE LARVA, "DOBSON." 



other names. The female fly has short pincers, like 

 the larva, but the male has two long "horns," which 

 cross at the tips. 



The little "water boatman," which rows himself 

 along, cannot harm fish to any extent. Trout will not 

 eat them, nor will they touch "whirligigs," which play 

 in schools on the surface; nor will they taste of the 

 water cricket, "skater," or "skeeter," as it is variously 

 called the little, dried-up fellow which stands on the 

 water with only its feet touching it. These water 

 crickets eat small insects, but seem to get no good 



