File:Insects and insecticides - A practical manual concerning noxious insects and the methods of preventing their injuries (1904) (14579156927).jpg

Identifier: insectsinsectic00weed (find matches)
Title: Insects and insecticides : A practical manual concerning noxious insects and the methods of preventing their injuries
Year: 1904 (1900s)
Authors: Weed, Clarence Moores, 1864-1947 Metcalf Collection (North Carolina State University). NCRS
Subjects: Insect pests Insecticides
Publisher: New York : Orange Judd Company
Contributing Library: NCSU Libraries
Digitizing Sponsor: NCSU Libraries

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. Magnified. seems to have been overlooked, the badly diseased leavespresent a slightly thicker, corky aj^pearance; otherwisethe disease is not readily apparent, especially where notsevere. This green stage lasts about a week or ten days,and about June fifteenth the spots may be found chang-ing to a dark brown color, beginning on the lower sideof the leaf. The tissue of the diseased parts or spotsthen presents a dead, dry, brown or black, corky appear-ance. The spots are also more conspicuous on the lowerside, and remain unchanged until the leaves fall in theautumn. They occur either singly, scattered over thesurface of the leaves, or often coalesce, forming largeblotches which sometimes involve a large portion of theleaf. The authors of this mischief are extremely minuteeight-legged mites which resemble when magnified Fig.52. Mr. Slingerland who has studied the species mostcarefully thus describes its life history : The exceed-ingly minute oval grayish eggs are laid by the females iu
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P4 H EmO OH O THE PEAR LEAF MITE 105 the spring mthin the galls that they have formed, andhere the yonng are hatched. How long they remainwithin the gall of their parent has not been ascertained.But sooner or later they escape through the opening in

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