42 
clover fields of the university farm we have taken two hundred species 
of insects — not all of them injurious, tho more than half of them feed 
on the plant. Adding to these the other species that have been listed 
as feeding on clovers, vetches, and alfalfa, it is seen that these plants 
are food for more than two hundred different kinds of insects. A 
hundred more are predaceous or parasitic on these clover insects, or 
else feed on animal or vegetable matter in the soil of the clover field. 
No part of the plant escapes attack. The roots are eaten by the 
larvae and the beetles of the root-borer, as well as by those of half a 
dozen other species, and are drained of their sap by the mealy bug. 
The stem is hollowed out by the common stem-borer. Both the stems 
and the leaves are pierced by many hemipterous insects, especially 
aphids and jassids, and are eaten by a great variety of caterpillars, 
beetles, and grasshoppers, as are also the heads of the flowers. The 
ovule is destroyed by the maggot of the seed-midge, and the developing 
seed is eaten out by the seed-chalcid. Even clover hay is the special 
food of a certain caterpillar, hence called the clover hay-worm. 
Some of the insects of the clover field are, of course, beneficial. 
Such are those that pollenize the flowers, — bumblebees and, to some 
extent, honey-bees, — as well as those that act as checks on the injurious 
insects. 
Most of the clover insects are not limited to clover, but have other 
food plants as well. The seed-midge and the seed-caterpillar are, how- 
ever, confined to the clovers, and the seed-chalcid to clovers and alfalfa, 
so far as known. The root-borer is said to eat peas as well as clover. 
The hay-worm has been found only on hay as yet, but the moth has 
been raised from masses of dead grape leaves taken in a vineyard. The 
leaf-weevil is reported from beans and timothy, as well as clover and 
alfalfa. The clover-louse has been a pest of the worst kind on peas 
and has a long list of food plants. Of the less important clover in- 
sects,^ a few have no other food plant ; but the majority can easily main- 
tain their existence when no clover is at hand. 
In Illinois, where alfalfa is a recent introduction, its insects are 
essentially the same as those of red clover, and it has as yet no insects 
peculiar to itself. The leaf-weevil, seed-chalcid, and root-borer feed 
on alfalfa, but not enough to have done any damage up to the present 
time. Even the numerous caterpillars, beetles, and grasshoppers that 
eat the foliage have not yet injured this newly introduced plant to any 
great extent. An insect that eats a few alfalfa leaves is not necessarily 
inflicting permanent injury upon the plant; for, up to a certain point, 
the plant is injured by leaf -eating insects no more than a fruit tree is 
injured by pruning. Red clover, also, is such a vigorous plant that it 
easily withstands or repairs injuries of an ordinary kind. Thus in 
April, 1907, 25 to 50 percent of the new leaves of red clover were 
frozen and killed in this region, but the hay crop was as good as ever. 
The temporary damage was far greater than that ordinarily inflicted 
by the miscellaneous clover insects — leaving out of consideration the 
seven pests nam^^d in the previous paragraph. 
