Tue Insect Faunas OF THE GENUS CRATAEGUS 1053 
live (fig. 103). The leaf does not become thickened in these galls. The 
galls become extremely abundant on some trees, so that almost every leaf 
is deformed. The mites seem to prefer the shady branches of trees, 
rather than those in bright 
sunlight. They become most 
abundant during August, 
when the galls are swarming 
with the microscopic white 
mites. The galls were found 
‘most abundantly on Crata- 
egus punctata, but they were yg. 103. cross SECTION OF A CRATAEGUS LEAF, 
found also on C. pruinosa THROUGH THREE SERPENTINE GALLS 
and other native hawthorns. 
Eriophyes sp. No. 2 (Hawthorn 
a marginal gall) 
Galls very similar to those 
of Hriophyes goniothorax Nal., 
which are found on hawthorns 
in Europe, are produced by 
Hriophyes sp. No. 2. The 
margin of the leaf is curled 
tightly downward for a dis- 
tance of two centimeters or 
more (figs. 104 and 105), and 
the curled margin is paler green 
than the rest of the leaf. The 
mites live within the curl. This 
gall is not very common about 
Ithaca, but was found in a few 
cases on Crataegus coccinea. 
Eriophyes sp. No. 3 (Thorn leaf 
pouch gall) 
Many small, pale green 
pouches, standing on the upper 
side of the leaf and opening 
Fic. 104. HAWTHORN MARGINAL GALLS beneath the leaf by a small slit, 
are caused by microscopic 
white mites which live within the pouches. The 
galls vary in size and shape, but are generally 
about two millimeters high and are rounded on top 
(figs. 106 and 107). They may be found at any 
place on the leaf except on the larger veins. Pa Ohe fe aes 
They are fairly common on Crataegus punctata arty rani) GAS 
but are not so abundant as the serpentine galls, OF LEAF 
