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Indiana University Studies 
ways large, polythalamous, and spiny. Where wheeleri and 
derivatus have hybridized, as in the hybrid variety erinacei, 
smooth and intermediate and spiny galls appear in about equal 
numbers. The hybrid wheeleri x pezomachoides, which we 
have recognized as variety advena of the Cumberland High- 
lands and southern Appalachians, has small galls which are 
only very finely spiny. Where wheeleri comes into contact and 
hybridizes with pezomachoides further east on the Atlantic 
Coastal Plain, as it does commonly about Boston and thru all 
but the easternmost edge of Virginia, the smooth galls pre- 
dominate, in many localities to the complete suppression of 
the spiny galls. One collecting galls in such localities would 
feel sure he had pure populations of pezomachoides, and only 
subsequent breeding of insects would show the wheeleri hy- 
brids actually present. 
The galls of wheeleri may be exceedingly abundant on indi- 
vidual white oak trees, falling to the ground still attached to 
the leaves in October and November. I have emergence rec- 
ords for November 7, 12, 13, 15, 16, 18, 20, 21, 22, 24, 25, 26, 
and 27 ; and for December 1, 4, 6, 8, 9, 10, 12, 15, 16, 17, 20, 22, 
23, and 24, and January 2 and 10. Most of the emergence in 
the north is in the latter half of November, that further south 
is in the first half of December. November emergence in the 
north comes during colder weather than the emergence for the 
other varieties of pezomachoides. In the neighborhood of 
Boston, the insects remain active on cold days, and in 1917 
and 1918 I repeatedly observed oviposition out-of-doors at 
temperatures down to 15° F. Crawling very slowly over the 
ice or snow-laden branches, with their antennae bent forward 
and moving in a way that would suggest their function as 
organs of smell (compare the sensory structures noted by 
Triggerson for variety erinacei) , the insects finally reach dor- 
mant, lateral or terminal buds of the oak. The gall makers are 
negatively geotropic, as simple experimentation under con- 
trolled light conditions easily proves, and when both the 
light and gravity stimuli serve to send them upward they 
reach the tips of the branches — tho not necessarily the highest 
branches — of the trees. I have on several occasions observed 
insects start from among the dead leaves on the ground, climb 
the trunks of the trees, and arrive at the ends of large 
branches. 
