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time. The usual method of prevention recommended is that of re- 
moving the egg clusters in the fall. The eggs are laid by the female 
upon the outer surface of the cocoon from which she has just 
emerged, forming very conspicuous objects upon the leafless limbs. 
As they do not hatch until May or June, they may be removed at 
any time in the winter or early spring. Doubtless, if this has been 
neglected, the spraying of the foliage during the months of June or 
September with Paris green or London purple, suspended in water, 
would also be a perfect remedy. 
Tue Bac-worm (Thyreodopteryx ephemereformis, Haw). 
Fig. 21.—The Bag-worm, (Thyreodopteryx ephemerwformis, 
Haw). a, Larva, fully grown; b, male chrysalis; ec, female 
moth; d, male moth; e, bag containing female chrysalis, 
with eggs; f, fully grown larva carrying its bag; g, young 
worms. 
The general abundance of this pest upon cedars and some other 
trees in Southern Illinois calls for special mention.. The small 
conical bags, attached to the twigs of the tree, cannot be mistaken 
for anything else. Many of these contain the eggs, which remain 
throughout the winter and hatch in the following May. They may 
consequently be removed and destroyea by hand in the winter and 
spring, or the trees may be protected by spraying with Paris green 
or other similar poison in June or July, when the worms are eat- 
ing the leaves. 
