HOST INDEX 
It ia asaumod that anyone with the curloeity to learn the name of a casually 
oollected gall will know the name of the host plant on whioh it occurred, or at 
least the common names of the native oaka. Therefore the first place to look is 
In this host index under the name of the oak where the galls are grouped accord¬ 
ing to the part of the plant on whioh they ooour. "Root” galls simply means that 
they ooour at the crown, often buried out of sight by forest litter* The name of 
•ach described species is followed by its number In the SYNOPTIC LIST where the 
original description is cited and where, if one has access to the entomological 
literature, a more complete description may be found. Otherwise the short charac¬ 
terization and the figure are the beginner's main relianoo for identification* 
In addition to the described species there are also Included brief descrip¬ 
tions of several of the more common kinds that have never been described or 
reared# many of these with a figure* Here is opportunity for the amateur to make 
some contribution to science. The primary purpose of this popular paper is to 
stimulate interest in the group and point out some of the taxonomic and biologl- 
oal problems involved* 
In descriptions it is of significance whether a gall occurs in spring or in 
fall, whether single or in numbers, on upper or lower aide of leaf and whether 
it oontaina many colls (polythalamoue) or only one larval coll (raonothalamoua)• 
In case the name of the oak is not known then the plaoe to look is in the 
NOTES ON ILLUSTRATIONS where all the root galls, regardless of host, are grouped 
together. So also the flower, acorn, stem and leaf galls. A single oollected 
speoimen may not fit any description here* It may not be a normal cynipid 
structure. A gall is sometimes attacked in its early stages by guests or para¬ 
sites and its size and structure greatly modified. If several specimens are 
found and on different trees it is probably the normal reaction of the tree to 
the stimulus of the gall maker. 
A stone gall is a hard,many-celled mass inside a mature acorn in late fall* 
A pip gall is one produced between the acorn and the cup of a mature or immature 
acorn. A plum gall ia red,globular,attached to the side of the acorn cup. 
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