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178 DISEASES OF THE COTTON PLANT. 
vegetable life, as they are so extremely minute as to escape 
the notice of the superficial observer. When they iafest 
grape-houses, or rose-busbes, it bas been recommended to 
dust the leaves while moist with flowers of sulphur. 
The Drop or Hang Worm. — (CEceticus ?) 
The " drop-worm," as it is commonly called, is occa- 
sionally found upon the cotton leaf, but generally infests 
the arbor-vitse, larch, and hemloct-spruce. It is also found 
upon many of the deciduous-leaved trees, such as the lin- 
den, negundo, and maple. Dr. Harris states that the fe- 
male worm never quits her case, but lays her eggs in the 
skin of the chrysalis, in which she herself also remains until 
the eggs are all deposited, when she closes the end with 
down, and crawls out of the case and dies. These eggs 
being hatched, the young worms, after they are hatched, 
make little silken cocoons, open at both ends, and are cov- 
ered with fi-agments of leaves, twigs, etc., in which they 
■conceal themselves, and drag them about wherever they 
move. These cases are enlarged as the insects increase in 
size, and are still carried about by the worms. When they 
change their places, they protrude their heads, the first 
three segments of the body, and six legs, from one end of 
the case ; but when the insects wish to rest, each case is 
fastened by a few threads to the leaf or branch, and they 
retreat within. When shaken from the tree by an accident 
or by high winds, the worms are able to suspend them- 
selves by means of small threads, and hang in the air ; 
hence the name. When young, they are often blown from 
tree to tree, and thus carried to a considerable distance 
from the place where they were hatched. 
The males and their cases are much smaller than those 
