44 



FOURTH ANNUAL REPORT OF 



THE APPLE-LEAF SKELETONIZER— Pemprfm Hammondi, N. Sp. 



(Lei)idoptera, PhycidiB.) 



[Fig. 21.] 





l|S It^l'/i il 



The leaves of apple trees, and especially of 

 young trees, are preyed ujjon by such a host of 

 ,-^^ insects that their histories alone would furnish 

 material for a good sized volume. The little 

 worm which forms the subject of this sketch 

 has never been described, and yet it is often- 

 times so injurious and its work is so intimately 

 associated with that of one or two other species, 

 with which perhaps it has been confounded, 

 ^ that an account of- it becomes doubly necessa- 

 B ry. Though having different habits, it is quite 

 I closel}' related to the better known Eascal 



^' 6 a ®, Leaf-crumpler. 



In the fall of the year the foliage of trees in young orchards, and es- 

 pecially in the nursery, often wears a blighted, corroded, rusty look, and 

 upon carefully examining it such ajjpearance will be found to result from 

 the gnawings of this little Skeletonizer. A badl}' infested orchard or nur- 

 sery presents such a decidedly- seared aspect that it attracts attention at a 

 great distance -, and while traveling by rail 1 have often pointed out the 

 -work of this insect and felt as sure of its presence in certain orchards, as 

 though I had closely examined the trees. 



The rusty appearance is produced by the worm feeding solel}^ on the 

 green pulpy parts of the ujjper surface of the leaf, and thus leaving un- 

 touched the more fibrous frame-work. In some cases the pulpy portions are 

 eaten off ver}^ thoroughly so that nothing remains but the semi-transparent 

 epidermis below, and the net-work of veins ; but more usually a certain 

 amount of the parenchyma is left and this it is which acquires a bright rust- 

 Ted appearance. The worm always covers the leaf with loose tender silken 

 threads, with which it mixes numerous little blacky gunpowder-like, excre- 

 mentitious grains; and it is under this covering that it feeds. It is semi- 

 gregarious, either living alone on the leaf, or in company within a bunch of 

 leaves tied together. 



The worm (Fig. 21, a) is usually of a brown color marked on the 

 back as at h, but it varies from brown to pale yellowish-brown or greenish. 

 The markings are pretty constant, however, and the distinguishing feature 

 consists of four conspicuous black shiny tubercles, with a pale basal an- 

 nulation near the head, as at c. 



The chrysalis is of a light brown color with no striking characters. It 

 is generally formed among the leaves, in a very slight cocoon, and often in 

 the folds made by a leaf-roller which is generally found in company with 

 it. In confinement I have known the worms to go below ground where 

 thej"- cemented their cocoons on the outside with grains of sand. 



