. Annual report. Entomological Society of Ontario; Insect pests; Insects -- Ontario Periodicals. 48 ON GRAPE YINE GALLS. COMPILED BT JOSEPH WILLIAMS, LONDON, ONTARIO. The Grape-Vine Apple Gall, (Vitis povmm) Walsh & Riley, Order, Diptera Family, Cecidomi/idce. The following discriptions have been compiled from the valuable reports of Prof C. V. Riley, St. Louis, Mo. Besides the leaf-gall caused by the Grape Phylloxera, the Grape Vine is subject to various other gall-growths or excrescences, the nature of which often puzzles the vine grower. 1 shall give an account of four of the most consp
. Annual report. Entomological Society of Ontario; Insect pests; Insects -- Ontario Periodicals. 48 ON GRAPE YINE GALLS. COMPILED BT JOSEPH WILLIAMS, LONDON, ONTARIO. The Grape-Vine Apple Gall, (Vitis povmm) Walsh & Riley, Order, Diptera Family, Cecidomi/idce. The following discriptions have been compiled from the valuable reports of Prof C. V. Riley, St. Louis, Mo. Besides the leaf-gall caused by the Grape Phylloxera, the Grape Vine is subject to various other gall-growths or excrescences, the nature of which often puzzles the vine grower. 1 shall give an account of four of the most conspicuous which are found in Missouri. They are all caused by Gall gnats (Ceoidnmyidce), thehirva^ of which are distinguished by being of an orange-colour ; but more especially by having on the upper surface, near the head, a horny process known as a breast-bone.* This process is variable in shape, but more often clove- shaped, Y-shaped, or oar-shaped. It always has a .stem, which is mostly hidden, and termi- nates in two projections or prongs (sometimes three in those which are oar-shaped), which are armed with sharp points. It is retractile, and the prongs may be exerted at will, and are doubtless intended to assist in abradins; the tissues of plants, so as to cause an abnormal flow of sap, which serves as food for the larvaj. That they have little, if anything, to do in causing the gall growth, we may infer from analogy, and from the fact that many Ceci- doniyidous galls are formed before the larva; hatches, and de- pend on something deposited with the egg. The perfect flies are of a dull black colour, like that represented at figure 37, (a female, b, antennie of male), aud many species so closely resemble each other, that it is next to impossible to distinguish ]i'i„.37 themwhendry. Thosewhich produce the galls here mentioned, are difficult to rear, and with one exception not yet known. The Grape-Vine Apple-gall has been a fruitful source of speculation, and has given rise t
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