434 INSECTS INJURIOUS TO VEGETATION. 



by ancient writers as fruits fair to the view, but crumbling 

 into dust when handled. A late writer,* however, has shown 

 that these tempting and deceptive productions are the real 

 fruits of a tree, the Asdepias ■procera^ resembling our common 

 silk-weed in its botanical characters. 



Clusters of three or four round and smooth galls are often 

 seen on the small twigs of the white oak. They are nearly 

 as large as bullets, of a greenish color on one side, and red on 

 the other. They approach in hardness to the Aleppo galls, 

 and perhaps might be put to the same use. Each one is the 

 nest of a single insect, which turns to a fly and eats its way 

 out, in June and July, having passed the winter as a chrysalis, 

 within the gall, lodged in a clay-colored egg-shaped case, about 

 three twentieths of an inch long, and with a brittle shell. 

 These little cases appear to be cocoons, but are not made of 

 silk or fibrous matter. Similar cocoons are found within many 

 other galls, and I have some which were discovered under 

 stones, and were not contained in galls, but produced gall-flies, 

 the insects having left their galls to finish their transformations 

 in the ground. The gall-fly of the white oak varies in color. 

 Sometimes it closely resembles the gall-fly of our oak-apple, 

 differing from it only in size, and in wanting the brownish 

 spot and dark-colored veins on the fore wings; and sometimes 

 it is of a dull brownish yellow color, with a brown spot on the 

 back. It is three twentieths of an inch long, and its wings 

 expand three tenths of an inch. It is the Diplolepis, or more 

 properly Ci/nips, oneratus of my " Catalogue." 



Galls of the size and color of grapes are found on the leaves 

 of some oaks. Each one contains a grub, which finishes its 

 transformations in June. The winged insect is my Cynips 

 7tuhilipennis, or cloudy-winged Cynips, so named from the 

 smoky cloud on the tips of its wings. Excepting in this re- 

 spect, it closely resembles the dark-colored variety of Ci/nips 

 oneratus, and very little exceeds it in size. 



One of our smallest gall-flies may be called Cynips seminaior, 

 or the sower. She lays a great number of eggs in a ring-like 



* Robinson's " Biblical Researches in Palestine," Vol. II., p. 235. 



