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JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 11 
a rate of infestation twice as great as the number of seeds produced by 
a normal head. In some fields where such heavily infested heads 
occur, the pedestrian will get his trouser legs very sticky on a level with 
the excessively sticky clover blossoms. Adjoining clover fields which 
have been cut at a slightly different time will have so few aphids or 
honeydew, that much destruction of the aphis evidently follows from 
the curing of the hay in the sun. 
The most abundant Syrphid flies have been reared and await de¬ 
termination. Far more numerous than these are the new species of 
Hymenopterous parasites (Aphelinus lapisligni How.) discovered inde¬ 
pendently by Mr. L. R. Rockwood and myself, mine having been first 
considered by Dr. Howard as either a different variety or a still differ¬ 
ent species. 1 (See PI. 13, figs. 1 and 2.) Seldom more than ten of this 
parasite occur per head of clover, and the parasitized jet black aphids 
appear more often in the lower leaf petiole bracts sheathing the stem 
than in the head, indicating an earlier attack of the parasites, before 
the clover blossom heads form. This also indicates that on some 
plants, the aphis infestation proceeds perhaps from apterous female 
aphids overwintering next the crown. 
Quite as numerous in some fields are the orange-yellow nymphs of 
the Western Dark Triphleps (T. tristicolor White), averaging from 
one to three individuals per clover head. These rapidly and more 
persistently penetrate all parts of the clover bloom and stem than 
all the other aphis enemies combined. 
Preliminary tests with orchard sprayers driven through the fields 
have shown that a majority of the aphids may be destroyed with 
nicotine sulfate and soap at usual strengths. We had thought to 
chronicle the discovery that Syrphid larvae and Triphleps nymphs, 
together with the adults of Syrphids, Coccinellids, Triphleps, and honey 
bees are little affected by this spray, appearing to be as lively as ever 
two to three days after application. However, in Maine Bulletin No. 
253, p. 221, Metcalf has laboratory proof of the survival of Syrphid 
larvae so sprayed. I have since found that where adult H. convergens 
are confined in small capsules of sprayed leaves, they die. After the 
spraying, natural enemies gain the upper hand. 
Sodium arsenite sprayed by orchard or field sprayers (formula based 
on that in Wisconsin—J. G. Sanders) has proved 99 per cent efficient 
against grasshoppers in many alfalfa and clover fields of all ages of 
growth; and the addition of nicotine for aphis does not make it burn 
worse. Over 20,000 acres were sprayed with arsenite, I was told, 
under the direction of the County Agents in 1916, but too much burn- 
1 Howard, L. 0. Proc. Biol. Soc. Wash., Mar. 31, 1917. Vol. 30: 77-8; personal 
correspondence. 
