^12 JOUENAL OF THE ROYAL HOKTICULTURAL SOCIETY. 



its way out of the shell. Most of them come out through the top covers, 

 but a few were observed in which the larva- had evidently emerged through 

 the lower surface of the egg, next to the apple or leaf. 



The young caterpillar is about one-fifteenth of an inch in length and 

 is of a semi-transparent colour. Later dark spots appear around the hairs. 



The young larva, after piercing the apple, makes a shallow mine just 

 under the skin. Those mines can be easily recognised by the lighter 

 colour and by the excrement which is cast out. The larvae which enter 

 by the calyx also take their first few meals at the surface inside the 

 calyx. 



By counting infested apples on unsprayed trees I found that about 

 ()0 per cent, of the larv* of the first brood enter at the calyx end. In the 

 later broods but few enter the calyx end. Many enter the apple at the 

 stem end. The greater proportion, probably from 60 to 90 per cent., 

 enter at any part of the apple. A favourite place of entrance is at the 

 point where two apples touch. 



At the end of four or five days the larva commences to tunnel toward 

 the central portion of the fruit. Arriving at the centre, it commences 

 irregular excavations, which are filled with excrement, the pellets of 

 which are bound together by silken threads. Surrounded by abundance 

 of food, the insect grows rapidly, casting its skin many times. I have 

 found many burrows, sometimes as large in diameter as a full-grown 

 larva, in which no larva could be found ; therefore I believe that some- 

 times a larva feeds upon more than one fruit. In all cases where fruits 

 touch they are both injured. 



While one larva usually feeds upon but one apple, one apple may be 

 eaten by many larv*. A large apple was found with thirteen worm- 

 holes in it, both entrance and exit, and three larvae, of various sizes, were 

 feeding inside. It is a very common occurrence to find from four to seven 

 holes in an apple. These different holes are usually made by insects of 

 different broods. In a badly infested orchard the earlier apples rarely 

 had but one insect in each. A larval stage of from ten to fourteen days, 

 as given by Professor Card, is, I think, nearly correct for Idaho. 



On summer apples and most fall apples the effect of the insect is to 

 cause the fruit to ripen prematurely. In the winter varieties, such as 

 Winesap, there is no such ripening. In all cases the fruit is rendered 

 unfit for use. When full grown the larva eats its way to the surface of 

 the apple. The burrow is kept closed by frass, or sometimes an adjacent 

 leaf is fastened over the hole with silk. Having eaten as much as it 

 desires, the larva pushes out the plug or removes the leaf and leaves the 

 fruit. In warm weather the worms, for the greater part, leave the 

 apples in the early evening or night ; but in colder weather, in the fall, 

 they emerge during the heat of the day. If the fruit has fallen, the larva 

 crawls along the ground to a suitable place to spin its cocoon. The 

 worms have two modes of leaving the fruit left on the tree. In some 

 cases they drop by a silken thread to the ground. I have observed a 

 larva hanging by this thread, and many threads were noted hanging 

 from the trees. The other, and by far the most common method, is 

 for the larvae to crawl from the apple to a branch and thence to the 

 tree- trunk. 



