116 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
Injury may be rather severe on important street and shade trees. 
Heavily infested trees may drop most of their leaves, and when this 
happens in conjunction with drought the trees may be seriously 
affected. 
A contact insecticide (p. 52) directed against the under side of the 
leaves and applied twice, at 2-week intervals, as soon as the young have 
hatched in the spring, should give adequate control. 
The oak lacebug 
ees arcuata 
(Say) ) feeds on various 
species of oak throughout 
the Eastern States north 
of the Carolinas and Ala- 
bama. 
This species may over- 
winter as either adults or 
eggs, but otherwise its 
lite history is similar to 
that of the sycamore lace- 
bug. Feeding by large 
numbers causes curling 
and whitening, then 
browning of foliage. 
Severe infestations may 
cause premature defolia- 
tion of the tree (fig. 19). 
Measures recommended 
for control of the syca- 
more lacebug are appli- 
cable for the control of 
this insect. 
A variety, Corythucha 
arcuata mali Gibson, 
closely resembles @. ar- 
cuata and is often found 
in association with it on 
oak. It, however, has 
also been recorded at 
times on hard and soft 
maples. 
Ficure 19.—Spotting of oak leaves caused by a Corythucha mollicula 
lacebug, Corythucha sp. O. & D. (=Salicis O. 
& D.) (=canadensis 
Parsh.), the willow lacebug, occurs throughout the Eastern States 
and when present in large number may seriously injure willow, its 
only known host. It is e: asily recognized by the lack of spines on the 
margin of the elytra, and may be controlled by measures recommended 
for the sycamore lacebug. 
The elm lacebug ((Corythucha ulmi O. & D.) has been recorded 
In many Eastern States and probably will be found wherever Amer- 
ican elm, its only known host. grows. Little is known of the life 
history of this species: however, heavy infestations may cause serious 
foliage discoloration, and this may happen as early as mid-June. The 
