82 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 16 
of the pea aphis, owing to the various difficulties that are always present 
in spraying. This is particularly true in the spraying of broadcast 
canning peas. 
Counts of the yields on infested and uninfested market peas grown 
in the fall of 1922 at Cambridge, Maryland, showed beyond doubt that 
the pea aphis does considerable injury. 
Table I. Effect of Aphis on Yield. 
Farm of W. A. Byrn, Cambridge, Md. 
October 19th, 1922 
Yield from 100 feet of heavily infested vines 
Number of pods with two or more peas 
Number of flat pods, unmarketable 
Estimated yield on basis of quantity picked 
Yield from 100 feet of uninfested vines 
Number of pods with two or more peas 
Number of flat pods, unmarketable 
Estimated yield on basis of quantity picked 
892 or 63% 
517 or 37% 
50 bushels 
1891 or 79% 
512 or 21% 
145 bushels 
A comparison of dusted and undusted fields shows that the yields on 
the former are higher and that the number of marketable peas is increased 
by control of the aphis. 
Table II. Effect of Dusting on Yield 
Hirst Farm, Cambridge, Maryland 
October 12, 1922 
Counts from 100 yards of undusted vines 
Number of pods with three or more peas per pod 374 or 37% 
Number of pods with one or two peas per pod 192 or 19% 
Number of pods with no peas 436 or 44% 
Counts from 100 yards of dusted vines, 35 lbs. per acre 5% dust. 
Number of pods with three or more peas per pod 1028 or 44% 
Number of pods with one or two peas per pod 682 or 29% 
Number of pods with no peas 634 or 27% 
Increase in marketable peas 17% 
The kind of dust material that gives the best results was tested on 
fall grown market peas. The tests show that nicotine alone, of all the 
materials tested, can be relied upon to give satisfactory results. The 
following table shows in brief the results with various combinations: 
Table III. Tests of Insecticides 
Jackson Farm, Cambridge, Md. 
Exp 
No. 
Date 
Kind of Dust 
Quantity 
in lbs. 
per acre 
Per cent 
kill 
Remarks 
1 . 
9/27/22 
» » 
Dosch 2.4% Nicotine 
45-55 
75-80 
Light, volatile dust 
2. 
Nicotine 3%, kerosene 5%, lime 
45 
75-80 
3. 
Nicotine 3%, lime 
55 
80 
4. 
Kilspray 5%. lime 
75 
10 
Pyrethrum extract 
5. 
Derrisine 5%, lime 
50 
10 
6. 
Nico-Tone, 1+1 % nicotine 
35 
15 
Very heavy 
7. 
Ace-Hy 
25 
10 
8. 
Check 
No unusual mortality 
9. 
Niagara 3%, nicotine 
50 
90 
10. 
Niagara 5%, nicotine 
45 
95 + 
Temperature 75°. Dry. Very little breeze. Noon to 4:30. 85% of plants infested at time of 
dusting. 
