Insect Study 



347 



THE CODLING MOTH 



Teacher s Story 



is difficult to decide which seems the most disturbed, 

 the person who bites into an apple and uncovers 

 a worm, or the worm which is uncovered. From 

 our standpoint, there is nothing attractive about 

 the worm which destr.jys the beauty and appetizing 

 qualities of our fruit, but from the insect stand- 

 point the codling caterpillar (which is not a worm 

 at all), is not at all bad. When full-grown, it is 

 about three-fourths of an inch long, and is likely 

 to be flesh color, or even rose color, with brownish 

 head; as a young larva, it has a number of 

 darker rose spots on each segment and is whitish 

 in color; the shield on the first segment behind the head, and 

 that on the last segment of the body, are black. When full-grown, the 

 apple worm is plump and lively; and while jerking angrily at being dis- 

 turbed, we can see its true legs, one pair to each of the three segments of 

 the body behind the head. These true legs have sharp, single claws. 

 Behind these the third, fourth, fifth and sixth segments of the abdomen 

 are each furnished with a pair of fleshy prolegs and the hind segment has a 

 prop-leg. These fleshy legs are mere makeshifts on the part of the cater- 

 pillar for carrying the' long body; since the three pairs of front legs are 

 the ones from which develop the legs of the moth. The noticing of the 

 legs of the codHng moth is an important observation on the part of the 

 pupils, since, by their presence, this insect may be distinguished from 

 the young of the plum curculio, which is also found in apples but which 

 is legless. The codling moth has twelve segments in the body, back of 

 the head. 



The codling larva usually enters the apple at the blossom end and 

 tunnels down by the side of the core until it reaches the middle, before 

 making its way out into the pulp. The larva weaves a web as it goes, 

 but this is probably incidental, since many caterpillars spin silk as they 

 go, "street yarn" our grandmothers might have called it. In this web are 

 entangled the pellets of indigestible inatter, makuig a very unsavory 

 looking mass. The place of exit is usually circular, large enough to 

 accommodate the body of the larva, and it leads out from a tunnel which 

 may be a half inch or more in diameter beneath the rind. Often the larva 

 makes the door sometime before it is ready to leave the apple, and plugs 

 it with a mass of debris, fastened together with the silk. As it_ leaves the 

 apple, the remnants of this plug may be seen streaming out of the open- 

 ing. Often also, there is a mass of waste pellets pushed out by the young 

 larva from its burrow, as it enters the apple; thus it injures the appear- 

 ance of the apple, at both entrance and e.Kit. It the apple has not received 

 infection by lying ne.xt to another rotting apple, it first begins to rot 

 around the burrow of the worm, especially near the place of exit. 



The codling caterpillar injures the fruit in the following ways: The 

 apples are likely to be stunted and fall early; the apples rot about the 

 injured places and thus cannot be stored successfully; the apples thus 

 injured look unattractive and, therefore, their market value is lessened; 

 wormy apples, packed in barrels with others, rot and contaminate all the 



