THE INSECT WORLD. 



275 



It is, indeed, a helpless, grub-like creature that awaits the visit 

 of the male without making an attempt to emerge from its sac, 

 in which it remains even after impregnation. The eggs develop, 

 finally fill up the bag, and then 



the female dies, the eggs rest- ^^^- 299- 



ing in the fluffy mass already 

 described until the spring fol- 

 lowing. 



This species is best treated 

 by picking off and destroying 

 the bags during the winter, and 

 if this is thoroughly done no 

 caterpillars will appear on the 

 trees in the spring, unless they 

 crawl on from other points 

 where an egg-sac may happen 

 to be attached. The meas- 

 ures recommended against the 

 ' ' white-marked tussock moth 

 can be employed here as well, 

 and trees once cleared can be 

 kept free without much diffi- 

 culty. When arbor- vitae is at- 

 tacked, the picking should be 

 thoroughly and carefully done, because these hedges suffer very 

 rapidly, and once defoliated, usually die. In orchards where 

 spraying is done against the codling-moth, the "bag-worms" 

 are destroyed incidentally and no special measures need be taken 

 against them. 



Next follows the family of " prominents," so called from the 

 fact that the moths frequently have a tooth at the inner margin 

 of the fore wings, and the caterpillars are sometimes a little 

 humped. They are technically termed NotodontidcB. Most ol 

 them have a small, retracted head, many of them a short or 

 obsolete tongue, and some are more or less troublesome on cul- 

 tivated plants. 



One of the best known is the "yellow-necked caterpillar" 

 often found feeding on apple-trees in colonies of from fifty to 

 more than one hundred. When full grown it is nearly two inches 



The bag-worm. — a, sack of female cut 

 open to show the grub-like creature at its 

 mouth; b, the female removed from the 

 bag, much enlarged. 



