CORN-LEAP BLOTCH MINER 
By W. J. Phillips, 
Entomological Assistant , Cereal and Forage Insect Investigations, 
Bureau of Entomology 
INTRODUCTION 
There have heretofore been no references in the literature of economic 
entomology to Agromyza parvicornis Loew (Houser, 1912), 1 the corn-leaf 
blotch miner; therefore, it might be termed a new enemy of corn (Zea 
mays). While this is literally true, its work has been recorded previously, 
although credited to another species (Comstock, 1881). Up to the present 
time it has not proved to be a very serious pest, mainly because of the army 
of parasites that attack it. It is, however, entirely within the range of 
possibility that considerable injury may be done in the partial absence 
of these natural enemies. Every adverse influence tends to decrease the 
vitality of the plant, and, when a small plant of only three or four leaves has 
one or two of these destroyed, its metabolizing power is greatly lessened. 
Even large plants, if subjected to a heavy infestation of this insect, 
would undoubtedly suffer seriously, as each miner larva is capable of 
destroying half a square inch of leaf surface; and the injury is permanent, 
since the tissues die. 
HISTORY OF THE SPECIES 
The adult (PI. Ill, fig. 1) was described in 1869 by Loew from a male 
and female from Washington, D. C. The late John B. Smith recorded it 
from New Jersey in 1909, but without reference to its habits. Prof. C. W t 
Johnson, of the Boston Museum of Natural History, stated in a letter to 
Prof. F. M. Webster, of the Bureau of Entomology, that he has collected 
this species at Niagara Falls, N. Y., and that Mr. S. A. Shaw took it at 
Hampton, N. H. 
In 1879 Mr. Theo. Pergande, of the Bureau of Entomology, reared a 
dipterous miner from corn leaves collected in Washington, D. C. A 
record of this rearing was published (Comstock, 1881) under the name 
Diastata , n. sp. This material can not now be located, but the description 
of the mines would indicate that it was Agromyza and in all probability 
A. parvicornis. 
During August, 1883, Mr. Pergande again reared the leaf-miner from 
com leaves at Washington, D. C. Each time only a few Diptera were 
reared, though numerous parasites were obtained. D. W. Coquillett 
(1898) published the record of this second rearing under the name 
Agromyza neptis. He later wrote a marginal note on his copy of the 
1 Citations to literature in parentheses refer to “Literature cited,” p. 30-31. 
(is) 
Journal of Agricultural Research, 
Dept, of Agriculture, Washington, D. C. 
Vol. II, No. 1 
Apr. is, 1914 
K—6 
