108 BULLETIN 932, U. S. DEPARTMENT OF AGRICULTURE. 



HABITS OF NEWLY HATCHED LARVJE. 



The natural instinct of newly-hatched insect larvae is to seek suit- 

 able food on which to commence feeding. In the case of the codling 

 moth the fruit of the apple and pear is the preferred food, but the 

 larvae will also attack the foliage and occasionally will burrow into 

 the tips of tender twigs. The injury to the foliage is of little conse- 

 quence, consisting of small holes through the lower epidermis, usually 

 where the leaf is fleshy, as at the junction of the veins with the 

 midrib. 



The frequency and amount of foliage feeding depend mainly on the 

 distance of the eggs from the fruit and the ease with which the 

 larva? find their ultimate object. Normally the earty-season eggs are 

 deposited upon the whorl of leaves about the fruit, while later in 

 the year many eggs are laid directly on the fruit. It has been ob- 

 served that some larva? spend considerable time before they reach 

 the fruit and that these satisfy their appetites on the foliage during 

 the interim. 



Upon reaching the fruit, the larva? seek a place of entrance, as 

 through the calyx, side, or stem. (See PL VI, A.) Some individuals 

 crawl over the fruit for some little time before making an attack, 

 while others proceed to enter with little hesitation. The larva? 

 will frequently take advantage of depressions or ruptures in the skin, 

 as frost pits, hail marks, or injury from other causes. 



The larva?, in starting to feed, tear away the skin by means of 

 their mandibles and cast most of it aside, consuming very little. 

 They first work directly beneath the skin, forming a shallow excava- 

 tion just large enough to accommodate them, and at the same time, 

 plug their entrance with f rass. 



THE CODLING-MOTH "STING." 



The so-called " sting " is caused by the larva? that succumb to the 

 poison before they are able to make more than the shallow excavation 

 above referred to. They sometimes die from natural causes after 

 having penetrated beneath the skin and occasionally they leave an 

 entrance hole to start a new one. 



CODLING-MOTH LARViE FEEDING ON PEAR TWIGS. 



On June 24, 1915, an examination of a pear orchard was made to 

 determine the cause of the browning of the leaves. At first sight the 

 orchard appeared to be affected with pear blight, Bacillus amylovorus 

 (Burrill) De Toni, but on closer inspection it was found that cod- 

 ling-moth larva? were responsible for the injury. There was practi- 

 cally no fruit in the orchard, owing to the spring freezes, and, as a 

 result, the larva? burrowed into the terminal ends of the twigs to a 



