SPRING CANKER WORM 87 



this stage the insect mines a leaf and, discarding the old case, makes 

 a new one from the upper and lower layers of the leaf. It becomes 

 full grown in June or July, fastens the case to a twig, and pupates 

 within. The pupal stage lasts ten days, after which the adults 

 appear as minute gray moths. 



Control. Spray with arsenate of lead as in the treatment of 

 codling moth. Repeat for five days. Kerosene emulsion used in 

 place of arsenical poisons is effective. In connection with kerosene 

 emulsion, note caution given in the chapter on insecticides. 



The Spring Canker Worm (Palecrita vernata Peck). The pale 

 grayish female moth with dark brown stripe down middle of back 

 and dark head is wingless ; somewhat fancifully referred to as 

 resembling a spider. The male is winged with a wing expanse of 

 about an inch; wings semi-transparent; brownish-gray; three indis- 

 tinct dark lines around the forewings. 



When full grown, the larva is three-fourths of an inch long, 

 cylindrical, with but one pair of pro-legs on middle of abdomen, 

 and it walks by " looping." The color of the larva varies from 

 ash-gray to green or yellow; the predominating color, however, is 

 dark-greenish olive or blackish. It is marked with narrow, pale 

 lines down the back and has a light stripe along each side. 



Life History and Injury. The moths emerge from their pupal 

 cells in the ground in March and April. The wingless females 

 then climb the trunks of trees. After the mating, the eggs are 

 deposited in irregular masses of about fifty each on or under scales 

 of bark, in cracks, crevices, and crotches of limbs and twigs. They 

 hatch in approximately a month. The young caterpillars begin to 

 feed on the expanding leaves, the larvae when first hatched eating 

 holes in the leaves and later eating the entire leaf except the 

 midrib. They may drop from the tree and hang suspended upon 

 strands of silk when disturbed. 



The caterpillar becomes full grown in four or five weeks; enters 

 the soil to a distance of two to five inches, hollowing out a cell in 

 the ground, which it lines with silk. It then changes to a pupa which 

 is about one-third of an inch long and light brown. The summer 

 is passed in this condition. 



Control. Thorough cultivation during summer will largely 

 destroy the pupae. The caterpillars are easily destroyed by a 

 spray of arsenate of lead, three pounds in fifty gallons of water. 

 The first spraying should be given as soon as the trees leaf out, 

 and the second as soon as the blossoms drop. The first is the more 



