ORCHARD INSECTS 311 



black and yellow tubercles, to almost black. The moths 

 have a wing expanse of about IT inches, and are pure white 

 or more or less spotted with black. In the North the moths 

 emerge late in June and lay their eggs in late July. Four 

 or five hundred eggs are laid in a patch on a leaf, and hatch 

 in about ten days. The young larvae at once spin a web 

 over the foliage on which they are feeding, which is enlarged 

 as necessary, so that before long it may cover a whole limb. 

 These webs are usually first noticed in early August in the 

 north and a month earlier in the Middle States. Within the 

 web the surfaces of the leaves are eaten off until they are left 

 dry and brown. The caterpillars then leave and form a new 

 web on a fresh branch, so that before long a tree may become 

 covered with the webs. The caterpillars become grown in 

 four to six weeks and then find secluded places under the 

 bark, in rubbish at the base of the tree, or just under the soil, 

 and there spin flimsy silken cocoons in which they transform 

 to small brown pupae, which hibernate over winter. In the 

 Middle States and farther south there are two generations 

 each year, the first generation of caterpillars appearing in 

 June and July and the second in August and September. 



Orchards which are well sprayed with arsenate of lead 

 for the codling moth will rarely be troubled with this cater- 

 pillar, but when unusually abundant it will be well to spray 

 with arsenate of lead for this and other leaf-eating cater- 

 pillars just as they are hatching from the eggs, which will be 

 about August first in the North. 



The Canker Worms * (1) are also common pests of or- 

 chard and shade trees, particularly of old orchards which 

 have been in sod and have not been sprayed. They are 

 among the most common of the "loopers" or "measuring 



* Paleacrita vernata Peck and Alsophila pometaria Harris. Family 

 Geometridce, see page 87. 



