74 
Journal of Agricultural Research 
Vol. I, No. i 
June until early September exceeds the highest mean temperature during 
the summer at Salt Lake City, Utah. This may in part explain the 
difference in habits of this insect at the two localities during midsummer. 
INJURY TO FIELD CROPS OTHER THAN ALFALFA 
MINING IN LEAVES OF COWPEA 
This leaf-miner has been found burrowing in the leaves of the cowpea 
in widely separated localities by several agents of the Bureau of Ento¬ 
mology. 
Dr. E. G. Titus,formerly an agent of the bureau, on July 12, 1904, found 
the leaves of the cowpea at Batesburg, S. C., generally attacked by leaf¬ 
mining larvae, most of which had already escaped from the mines. He 
was able to rear two adults of this species and one hymenopterous para¬ 
site. Messrs. G. G. Ainslie and Philip Luginbill have observed mined 
leaves at Columbia, S. C., the former in July, 1908, and the latter in 
September, 1912. Mr. Luginbill also reared adults and parasites of this 
insect from their mines in cowpea leaves on the plats of the experiment 
station at Purdue University, La Fayette, Ind., in connection with studies 
made at that point extending from July 6 to August 7, 1911. These 
miners were attended by great numbers of parasitic Hymenoptera, Euihri - 
chopsis agromyzae Vier. 
The junior author observed larval mines in cowpeas at several points 
in Mississippi during August and September, 1912, but in every case 
the larvae were parasitized or had escaped from the end of the mine 
through a slitlike opening and gone into the ground for transformation. 
Mr. George G. Ainslie observed considerable injury to the cotyledons 
of young cowpeas at Lakeland, Fla., May 8, 1912, there being from 2 to 12 
mines in each cotyledon—enough to make the leaves appear sickly and 
white. As many as 10 puparia were secured from moderately infested 
leaves. The larvae left the mine to pupate. 
The injury to cowpeas is seldom severe, because of the larger size of 
the leaf, but may become so when the larvae are present in sufficient 
numbers in the cotyledon of very young plants before there is sufficient 
foliage to withstand their attack. 
MINING IN LEAVES OF RAPE 
The larvae in large numbers were observed by Mr. W. J. Phillips to be 
mining in rape leaves at La Fayette, Ind., on July 6, 1909, and from the 
material collected adults of this species emerged July 9. Plate V, figure 
1, shows one of these leaves containing several larval mines. The larvae 
were observed to leave the mines and pupate on or beneath the surface of 
the soil, and the complete life cycle was found to be passed in from 25 
to 28 days. 
More extended studies were made of this species as infesting rape at 
La Fayette, Ind., during the season of 1912 by Messrs. Phillips and 
