flow to obtain tt. 2 
nN 
H 
frequently, but whether they actually remove anything from the 
fish, or simply anchor themselves, and there feed on very minute 
animalcule, we could never be quite sure ; but this much is certain, 
they do not leave behind them a scar of any sort that we could see. 
The members of the leech tribe (//rwdinea) are all more or 
less dangerous to fish. They leave scars which soon form 
suitable resting places for the spores of Safro/egnia, and this 
often proves fatal. The great flat-footed leech ( Geometra pisctcola) 
Fig. 44. Geometra piscicola (enlarged). 
and its cousin, the horse leech (dulostomum gulo), are both 
unwelcome visitors in fish ponds. The horse leech is very 
common in many waters, and is well known, and when it attacks 
fish, the loss of blood from its tri-radiate bite is very weakening. 
It is true that the trout will eat the leeches, but we much 
prefer keeping them out of the places where trout are, as they 
destroy more than they produce as food. In their youth, their 
principal food consists of the larvae of flies and small insects. 
‘They seem particularly fond of caddis worms and soon unhouse 
and eat them—indeed they seem almost designed by Nature to 
be the dé¢e noir of these creatures. All the leeches are free swim- 
mers, progressing by an undulatory vertical movement. They also 
crawl fast, and are capable of living for some time out of water, 
so they are not very easy to get rid of. Fortunately they are not 
very prolific ; about twenty eggs per annum seems to be their rate 
of increase. 
Most anglers will have met at some time or other with a 
beautiful greenish crab-like creature adhering to fish, which is 
commonly called a “tick.” They vary in size from one to three- 
