108 
INSECTS AS FOOD FOE FISH. 
they consume a much larger quantity of putrescent organic 
material than the quadrupeds and the birds which feed upon 
such aliment. 
Destruction of Insects. 
It is well known to naturalists, but less familiarly to com¬ 
mon observers, that the aquatic larvae of some insects consti¬ 
tute, at certain seasons, a large part of the food ot fresh-water 
fish, while other larvse, in their turn, prey upon the spawn 
and even the young of their persecutors.* The larvse of the 
mosquito and the gnat are the favorite food of the trout in the 
wooded regions where those insects abound.f Earlier in the 
year the trout feeds on the larvse of the May fly, which is 
itself very destructive to the spawn of the salmon, and hence, 
by a sort of house-that-Jack-built, the destruction of the mos- 
* I have seen the larva of the dragon fly in an aquarium, bite off the 
head of a young fish as long as itself. 
t Insects and fish—which prey upon and feed each other—are the only 
forms of animal life that are numerous in the native woods, and their 
range is, of course, limited by the extent of the waters. The great abun¬ 
dance of the trout, and of other more or less allied genera in the lakes of 
Lapland, seems to be due to the supply of food provided for them by ihe 
swarms of insects which in the larva state inhabit the waters, or, in other 
stages of their life, are accidentally swept into them. All travellers in the 
north of Europe speak of the gnat and the mosquito as very serious draw¬ 
backs upon the enjoyments of the summer tourist, who visits the head of 
the Gulf of Bothnia to see the midnight sun, and the brothers Lacstadius 
regard them as one of the great plagues of sub-Arctic life. “ The persecu¬ 
tions of these insects,” says Lars Levi Lsestadius \Gulex pipiens, Culex rep- 
tans, and Culex pulicaris ], “ leave not a moment’s peace, by day or night, 
to any living creature. Not only man, but cattle, and even birds and wild 
beasts, suffer intolerably from their bite.” He adds in a note, “ I will not 
affirm that they have ever devoured a living man, but many young cattle, 
such as lambs and calves, have been worried out of their lives by them. 
All the people of Lapland declare that young birds are killed by them, and 
this is not improbable, for birds are scarce after seasons when the midge, 
the gnat, and the mosquito are numerous.”— Om Uppodlingar i Lappmar- 
ken , p. 50. 
Petrus Lsostadius makes similar statements in his Journal for forsta 
drct , p. 285. 
