INSECT ENEMIES OF EASTERN FORESTS 521 
makes a subglobular, brownish leaf gall that shows equally well on 
both sides of the foliage. 
ULMUS (ELM) 
Oligarces ulmi Felt was described from material reared from the 
decaying bark of an elm in New York. It has also been reported as 
severely damaging the twigs of cedar elm in several counties in Texas. 
Famity AGROMYZIDAE 
The agromyzids are small insects, usually blackish or yellowish, 
with short antennae and a bare or pubescent arista. Oral vibrissae 
and mesopleural bristles are present. 
The larvae of this family differ from other leaf-mining Diptera 
mainly as follows: The head is incomplete and not differentiated from 
the thorax; a buccopharyngeal armature is present, the mouth hooks 
are usually quadrangular or triangular with two to four teeth; the 
posterior segment is not produced into a prominent tubercle. The 
maggots are small, 3 to 4 mm. in length, or slender forms of 1 mm. 
or less in diameter. 
These flies are essentially phytophagous and have a wide range of 
hosts. Most of the species belonging to the genus Agromyza are usu- 
ally stem and root miners, although a few species mine beneath the 
bark, and a few are gall makers. The species of the genus Phytomyza 
are leaf miners. Dipterous leaf miners of woody plants are few in 
number, and, with the exception of the holly leaf miner (Phytomyza 
ilicits (Curt.), none have caused injury serious enough to warrant con- 
trol measures. 
Leaf Miners 
Agromyza clara Mel., the catalpa leaf miner, makes a serpentine 
mine which later becomes a blotch mine often involving the entire leaf. 
The host plant is Catalpa bunget. 
Agromyza ulmi Frost., the two-winged elm leaf miner, mines the 
leaves of American elm. The species has a single generation, over- 
wintering in the puparium and emerging as adult early in the spring. 
A. viridula Coq. makes a blotch mine in the leaves of red oak. The 
larva of A. melampyga Loew makes a curved linear mine in the leaf 
of mock orange that later expands at its distal end, forming a blotch 
mine an inch or so long and half as wide. 
The holly leaf miner (Phytomyza ilicis (Curt.) ) makes a tortuous 
yellow-brown mine in the new foliage (fig. 142). Several kinds of 
holly are attacked. The adults appear early in the spring and have an 
extended emergence period. ‘There is only one generation, the species 
passing the winter in the puparium within the mine. Satisfactory 
control has been obtained by Felt and Bromley (754) by using a spray 
of 2 gallons of volck, 1 pint of nicotine, and 1 pound of lead arsenate 
to 100 gallons of water. The spray was applied when the adults were 
about to emerge. On small plants an infestation can be greatly re- 
duced by picking off the infested leaves and destroying them. 
An introduced European species, Phytomyza obscurella var. nigri- 
tella (Zett.) Mel., mines the leaves of wild black cherry, peach, and 
bush honeysuckle. The mine is linear in form, the frass being ar- 
ranged in conspicuous rows of spots along the center. There are two 
generations a year, the species overwintering in the puparium. 
