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 

 to some curious botanical theories, as the following extract will attest : 



An Apple Growing on a Grape-vine. 



A Vci/('>abIcPhe7iomenon. — In the garden of Capt. David B. Moore, Lexington, Va., 

 there is growing on a grape vine, a fully developed apple. On one side of the apple is an ap- 

 pearance of what might have been a grape-bloom. This interesting lusus natwrm is, as far 

 as we know, without; precedent, and of course has attracted marked attention, and caused no 

 little speculation in the circle learned in such matters about Lexington. The prevailing 

 opinion, we learn, is that an apple-bloom falling accidently upon a grape-bloom, became in- 

 corporated with it and produced the result ; but, if so, is it not singular that such an acci- 

 dent has never occurred before ? And, if so, again, does it not teach that the grape and 

 apple may be grafted on each other ? We hope the pomologists of Lexington will note very 



* This process is said by all authors with whom I am acquainted, including Baron Osten Saoken, to be 

 neutral, for which reason I suppose, it has been called the " breast-bone." I believe myself that it is dorsal. 

 As, however, it sometimes has a good deal the form of the breast-bone, or " wish-hone" of a (owl, the term may 

 be retained, though conveying a wrong idea. The larva? are also said to differ from all other insect larva) in 

 having fourteen joints. I have examined a great number of Cccidomyidous larvje without being able to make 

 out any such abnormal number, while in many species it is difficult to detect m<Te than twelve and a subjoint. 

 Usually, I have been able to clearly make out thirteen joints and a subjoint, which is,the normal number iu 

 insects. (Rules.) 



