234 
WISCONSIN STATE AGRICULTURAL SOCIETY. 
INSECTS INJURIOUS TO AGRICULTURE. 
Aphides (Plant Lice.) 
BY P. K. HOY, M. D. * 
From advance sheets of the Transactions of the Academy of Arts, Sciences and Letters. 
Entomology, the history of insects, their metamorphoses, 
habits, relation to plants, etc., is a branch of natural history 
which has peculiar claims on the agriculturist. In view of the 
millions of dollars annually lost to the state by the depreda¬ 
tions of insects, it becomes an interesting problem how to dis¬ 
tinguish, in all stages of growth, our insect friends from our 
insect foes, that we mav be the better fitted to cherish the one 
and destroy the other. 
When will the representatives of the people understand that 
Wisconsin can ill afford to dispense with the invaluable ser¬ 
vices of a state entomologist ? We have a host of insects, pe¬ 
culiarly destructive, waiting for careful study, the better to en¬ 
able us to counteract their evil work. Not the least of the ad¬ 
vantages to be derived from the labors of an active, enthusi¬ 
astic state entomologist, is the education of the farmers by 
personal contact; thus teaching them how to distinguish the 
various insects by which they are surrounded, in their different 
stages, so that this practical knowledge may be of value to 
themselves and to their neighbors. 
Plant Lice. —Small, green, brown, black or white, soft 
bodied insects, with or without wings ; crowding together on 
leaves, stems, bark or roots of various trees and herbs. Many 
species are covered with a white cotton}' substance, hence called 
Woolly Aphides. The number of species is very large, not a 
germ of plants that has not its peculiar species ; many, more 
than one. The apple alo'ne, according to Eitch, has not less 
than five species of plant lice. One of the most common spe¬ 
cies infest the tender leaves of the apple, the Aphis Mali , Fab. 
