144: FIRST ANNUAL REPORT OF 



THE WHITE-MARKED TUSSOCK MOTH— Orgyia leuoosligma, 

 Sm. & Abbott. 



(Lspidoptera, Arctiidse.) 

 [Fig. 81.] 



a b c d 



During the winter little bunches of dead leaves are sometimes 

 found to be quite numerous on our apple trees. They are generally 

 fastened to the twigs, and upon examination are found to contain gray 

 cocoons. The greater portion of these cocoons have an egg-mass 

 glued to them, which is composed of numerous perfectly round, cream- 

 colored eggs, of about 0.03 diameter, and partly covered with glisten- 

 ing while froth-like matter; while the other proportion of these cocoons 

 have no such egg-mass. 



About the middle of the month of May these eggs begin to hatch, 

 and continue thus to hatch in different parts of the orchard for over a 

 month. The young caterpillar which hatches from these eggs is rep- 

 resented at Figure SI, b. It at first measures 0.10 in length, and is of 

 a dull, whitish-gray color with the underside paler or oi' a dirty white, 

 and with the tufts on the back of a dark brown. In two days after 

 hatching, orange spots commence to appear along the back, and espe- 

 cially on segments 2, 3, 8 and 9. On the seventh day after having re- 

 mained stationary for about two days, fastened to some part of the 

 tree with silk, it casts its skin for the first time, after which operation 

 the hairs are more numerous, the dark portions more intensely black- 

 the orange parts of a brighter orange and the two tufts near the head 

 longer. As it approaches the time of the second moult, the underside 

 becomes more glaucous, a yellow line begins to appear at the sides, 

 and in some cases the orange marks become yellow, with the excep- 

 tion of a small, perfectly round spot on segments 9 and 10 which al- 

 ways remains orange; the neck or first segment, where it joins the 

 head, also becomes orange or yellow. Six days from the time of the 

 first moult the second moult takes place, the worm having become 

 lighter colored each day. Immediately after the shedding of the sec- 

 ond skin it measures 0.30; the collar is more intensely orange as well 

 as the head, while four cream-colored tufts appear on the back of seg- 

 ments 4, 5, 6 and 7, and the two round spots on segments 9 and 10 are 

 of a very bright scarlet-orange. As it grows and approaches the third 

 moult, the orange collar becomes more conspicuous, the back be- 

 comes of a perfect velvety black; the cream-colored tufts become 



