spring, and adults begin to appear in late May. Several other species of Marmara 
have been recorded mining the inner bark of twigs of balsam fir, oak, willow, and 
other trees (433). 
Phyllocnistis populiella Chambers, the aspen leafminer, is widely distributed in 
southern Canada and the Northern States. It feeds on various species of poplar, 
especially quaking aspen. In the Eastern States, it has been recorded as far south as 
West Virginia. Eggs are laid near the tips of young leaves in the spring. The larvae 
form tortuous mines in the leaves (fig. 43), mostly on one side of the midrib (237). 
Noticeable infestations have been observed in Maine. 
-F-506745 
Figure 43.—Small track mines of Phyllocnistis 
populiella, the aspen leafminer. 
Phyllocnistis liriodendronella Clemens larvae mine the undersides of young 
leaves of yellow-poplar, and P. magnoliella Forbes mine the undersides of young 
leaves of magnolia. The mines originate near the outer margins of the leaves and 
continue tortuously until large portions of the upper surfaces are detached. The 
damaged areas have a bluish cast. P. liquidambarisella Chambers mines the leaves 
of sweetgum. 
The larvae of Parectopa robiniella Clemens feed in the leaves of black locust, 
forming triangular, blisterlike mines. 
Parornix geminatella (Packard), the unspotted leafminer, occurs throughout the 
Northern States, west and south to Colorado, Virginia, and Arkansas. Its hosts are 
apple, quince, pear, sour cherry, pin cherry, plum, and hawthorn. Eggs are laid on 
the undersides of the leaves, and the larvae devour all of the tissues between the 
upper and lower surfaces of the leaves. Four generations per year have been 
recorded in Virginia. 
The lilac leafminer, Gracillaria syringella (F.), an introduced species, occurs in 
many of the Northeastern States and southeastern Canada. Its hosts are listed as 
lilac, black ash, privet, and euonymus. The adult has a dark-brown body and a 
wingspread of about 10 mm. The forewings are brownish except for six irregular 
transverse patches of yellow, and the hindwings are grayish brown. Full-grown 
larvae are pale yellowish, translucent, and about 8 mm long. Early instars feed 
gregariously inside the leaves and produce blotchlike mines. Later, they abandon 
their mines and roll or web together several leaves on which they feed from within 
this shelter. There are two generations per year. Injured portions of infested leaves 
dry up and become unsightly. Raking and destruction of fallen leaves is a good 
control practice. 
131 
