186 |3HIO EXPERIMENT STATION: BULLETIN 194 



softei portions of the leaves causing the remainder to die. Occas- 

 ionally, as the larvae approach maturity, the food supply is exhausted 

 within the vyeb and they wander to adjoining twigfs. The pupal 

 stage is passed in a thin cocoon, usually located in trash on the sur- 

 face of the ground or just below the surface, , 



Both sexes are winged moths, white, or white dotted with black. 

 The eggs are deposited upon the leaves. 



Because of the conspicuous web, one of the common methods 

 used in combatting this pest is clipping the twigs from the tree to 

 which the masses are attached and destroying them. This, however, 

 involves a loss of a part of the tree and for this reason it is preferable, 

 where possible, to spray with arsenicals when the young caterpillars 

 are known to be emerging. This occurs during the month of June. 

 See Plate 9, Fig. 2. 



„ , „^ Insects of the class to which the one 



The Bag or Basket Worm, ^^^^^ ^^^^^^^ consideration belongs, 



Thyridofteryx ephemerae- ^^^.^^ ^^^^^ p^p^j^^ .^^^^ ^^^^ ^^^ 



formis Haworth. ^^^.^^^ ^^^ ^^ ^^^^^^ ^j^.^j^ ^^ ^^^. 



structed during the larval stage. Soon after the larva is hatched it 

 contracts for itself a silken sack, smooth inside, while to the outside 

 are attached portions of bark, leaf tissue, leaf petioles, etfc. From 

 the open end of the bag the larva protrudes its head and fore legs, 

 and thus walks about at will, dragging its home with it. To one un- 

 accustomed to , the sight it is indeed a surprise when the curious 

 semi-shapely bundle of trash that has attracted his attention, sud- 

 denly develops life and moves away. 



As the enclosed larva grows, the bag is enlarged from time to 

 time by additions to the open end. Upon reaching maturity the 

 larva binds its case to a limb and pupates. At the end of the pupal 

 stage the males emerge and fly about, while the females, being 

 wingless, oviposit within their old cases and afterwards wriggle out 

 to fall upon the ground and die. 



The winter is passed in the &^s stage. 



A number of bag-constructing insects occur in Ohio: one, a small 

 species, and quite common, covers its bag with portions of grass 

 stems, and the empty cases may be found attached to fence posts, 

 etc. The one under discussion is a comparatively large species, 

 the completed bag varying in length from 1>^ to 2 inches. It was 

 observed doing considerable damage to shade trees during the past 

 season in the central and south-western portions of the state. 



A large number of trees and shrubs serve as food plants, the 

 ones most commonly found during the past season being sycamore, 

 horse chestnut, hard maple and willow. The most severe case of 

 attack coming to the author's attention was upon hard maples in 

 Cincinnati. See Plate 11, Fig 2. 



