236 NORTH AMERICAN INSECTS. 
wasps; viz., that of the Cynips oneratus (Fig. 64), and Cynips 
seminator (Fig. 65), both found on the white oak. 
At almost any season of the year, by examining the 
small twigs of the white oak, we may find around them 
clusters of oak-balls, of the size of a small marble, which 
are as hard as wood. ‘These hard excrescences are the re- 
sults of the punctures made in the tender twigs by the 
Cynips oneratus, who at the same time deposits its eggs in 
them. The swelling of these punctures is caused by the 
gradual enlargement of the egg, and also by the continual 
irritation of the little maggot, who is thus furnished with 
food and a secure dwelling until it is ready to perforate 
the oak-ball and come forth as a perfect four-winged wasp, 
which metamorphosis usually takes place in June or July. 
This little wasp is very small, being only about the sixth 
of an inch long. 
Oak-balls of this kind are found every where in North 
America, and they might possibly be substituted for those 
we receive from the Levant, and which constitute such a 
valuable dye-stuff. They have never been used as such to 
our knowledge; but the suggestion is well worth the atten- 
tion of chemists and dyers; for, if experiment should prove 
them as valuable as the foreign oak-balls, a vast amount 
Figure 65, 
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The Sower Gall-wasp. 
