BULLETIN 265, U. S. DEPARTMENT OF AGRICULTURE. 



DESCRIPTION. 



THE EGG. 



The egg of the dock false-worm is bean shaped or kidney shaped, 

 and somewhat flattened, pearly white, and with a soft, pliable shell. 

 It is protected by the tissues of the leaf in which it is deposited, 

 (PI. I, fig. 1.) The average length is 0.8 mm., and the width 0.6 mm. 

 About a day before hatching a dark spot shows through, which is 

 one of the eyes of the larva, the head being seen from the side. 

 Shortly before the larva breaks through the shell the outline of the 

 head is discernible. 



THE LARVA. 



The larva would not ordinarily be noticed on the plants until 

 nearly full grown, and it appears at this time as a slenderj hairless 

 larva, with a finely wrinkled olive-green or blue-green skin and a 



scattering of conspicuous white 



Fig. 2.— The dock false-worm: a, Full-grown larva, 

 enlarged; b, seventh larval segment, much en- 

 larged; c, portion of cranium, highly magnified; 

 d, actual length. (Original.) 



tubercles. After passing the last 

 molt, which brings it to the stage 

 in which it bores into pithy stems 

 or apples, the larva changes in ap- 

 pearance. (Fig. 2. ) It is no longer 

 velvety, but has rather a sleek, 

 shiny appearance, though the wrin- 

 kles still persist. Its color is a 

 brighter green — more of an apple 

 green — and the larva seems almost 

 translucent, since the alimentary 

 canal is empty. The tubercles are 

 no longer white and can not be dis- 

 tinguished. If an infested stem or apple be cut open, the larva within 

 will be found to have much the same appearance as before it entered, 

 except that it has become shrunken and curved and has lost the power 

 of locomotion. A detailed description of the various larval stages 

 follows : 



Firstinstar. — Length, 2.25 mm. General color very light gray ; food showing through 

 green. Somewhat slug shaped, thoracic region slightly enlarged, body tapering 

 gradually posteriorly, wrinkled. Head olive brown changing to dark brown, shining; 

 eyes shining black. Just before molting the larva has a shiny, swollen appearance and 

 is somewhat lighter in color. 



Second instar. — Length, 4.5 to 5 mm. As before; body wrinkles showing plainly. 

 Head very dark brown, nearly black. 



Third instar . — Length, 6 to 8.5 mm. Dorsum greenish gray, merging gradually into 

 the very light yellowish gray of the rest of the body. Body surface wrinkled, dull, 

 numbers of small, sparsely-set setae being noticeable laterally; surface minutely 

 reticulated, these reticulations being slightly raised and gray dorsally. Head olive 

 brown; mouth parts dark brown; eyes black; thoracic legs same as body, joints marked 

 by dark-brown Lines. 



