DISEASES OF THE APPLE TREE ] 281 



of the leaf by the larvae of Ornix petiolelta Frey., 

 Cemiostoma scitella Zell., Nepticula pulverosella Stt., 

 and Lithocoiletis coryhfoliella Hw. Tortuous tunnels are 

 produced on the upper surface of the leaf by the 

 larvae of the following: Nept cula aeneella Hb., N. 

 desperatella Frey., N. Pomella Vaugh., N. oxyacanthella 

 Stt., and N. malella Stt. Deep tunnels visible on both 

 surfaces of the leaf are produced by the grub of 

 Lyonetia Clerkella L. On the lower surface of the 

 leaf tunnels are made by the tiny grubs of the following 

 species: Lithocoiletis pomifoliella Zell., L. apparella H.S., 

 and Incur varia pectinea Hw. 



In large web-like structures which cover whole 

 branches are found the following larvae which eat both 

 the leaves and the blossoms in continental orchards: the 

 dark grey larva of Porthesia chrysorrhea L., having two 

 red lines along its back and two white lines at the sides ; 

 the ashy-grey hairy larva of Aporia Crataegi L. black 

 above, with two orange yellow lines along the back, and a 

 reddish line on each side just above the feet ; the greyish 

 brown larva of Vanessa polychloros L., having a yellowish 

 line on each side of the back; the black blue larva 

 of Bombyx lanestris L., having two lines of orange 

 yellow protuberances on the back, and three white 

 dots on each segment of the body. The larvae of 

 Hyponomenta malinella Zell. live together in large 

 colonies on the branches, surrounded by a large veiling 

 of web, eating and destroying the foliage. These larvae 

 are yellowish grey, with a black head, and two series 

 of black spots on the back, and three such lines of 

 black dots on each side. The larger dirty grey larvae 

 of H. padella L. behave in the same manner. There 

 is no remedy against these larvae except picking by 

 hand, and crushing them or throwing them in an 

 insecticide solution; but more than by human agency 

 these grubs are kept in check by being preyed upon 

 by insectivorous birds. 



