40 
when they are likely to spin down and wander about. They change 
to the chrysalis (Fig. 41, 6) within the bags, which they fasten to 
the twigs of the trees as a preliminary, but the grublike female 
moth, destitute of wings and with only minute and useless legs, 
deposits her eggs within her native sack, works her way out of it, 
drops to the ground exhausted, and dies. The winged males (Fig. 
41, (/) appear in September and October, and soon thereafter the 
eggs are laid. 
The bag- worm is a southern insect in its general range, and is 
rarely seen in northern Illinois. It increases in importance south- 
ward, and in southern Illinois is often a troublesome pest. In a 
general trip to eighteen towns, well distributed thruout the state, 
Mr. J. J. Davis, in 1910, found the bag-worm in four out of six 
southern Illinois towns visited, but in no others. 
The simplest method of destroying these insects is to collect the 
bags during the winter and burn them — a thing easily done with the 
aid of pruning shears if they can not be reached by hand. If this 
measure is neglected, infested trees may be cleared by spraying them 
with arsenical poisons soon after the hatching of the eggs — the latter 
part of June or early July. A pound of arsenate of lead to forty 
gallons of water is a safe and efifective poison. 
The Poplar and Willow Borer 
{Cryptorhynchns lapathi Linn.) 
The weeping Avillow, the Carolina poplar, the balm of Gilead, and 
the red birch are ornamental trees of sufficient popularity to make 
the existence of any insect pest destructive to them a matter of gen- 
eral interest. The Carolina poplar especially has had an enormous 
distribution of late years in Illinois towns, largely because of the 
ease and certainty with which it may be raised, and the rapidity with 
which it grows in our soils. 
The advent into this country nearly thirty years ago of a 
European snout-beetle well known in the Old World as a destroyer 
of alders, poplars, and willows, and occasionally injurious to birches 
also, has seriously endangered our American plantations of these 
trees. Detected first in New York in 1882, and found on Staten 
Island in 1886, it appeared in considerable numbers near Buffalo by 
1896, and the following year was reported as abundant in Boston. 
Mass., and very destructive there to willows and poplars of all kinds, 
and to the red birch. By 1901 it had reached northeastern Ohio; in 
1903 it was found in two Wisconsin nurseries; and in 1904 it was re- 
ported from North Dakota in poplars lately brought into that state 
from New York. In Illinois it was first seen by us in 1908 in Caro- 
lina poplars at Chicago ; but once detected there it was soon found 
to be generally distributed and very destructive to both poplars and 
willows in all parts of the city. (Fig. 43.) It has not yet occurred, 
