54 ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 
PEAS 
The Pea Aphis 
Macrosiphum destructor Johnson 
This is a large pale green species which 
winters on clovers and other leguminous 
plants and migrates to peas shortly after 
they appear above ground. Sometimes 
there will be an invasion in the late fall 
from the wild hosts. This louse is very 
susceptible to fungus attacks. When 
abundant the lice are capable of ruining 
a whole crop in a few weeks. 
Fig. 10. Destructive Pea Louse. Winged Vivip- 
arous Female. Enlarged six times. 
Control 
Peas grown on well fertilized land are 
more resistant to the attacks of the 
aphids, and earlier varieties escape much 
of the injury. On large areas the best 
method of control is to brush the lice off 
the peas with pine boughs and as soon 
after as possible cultivate down the 
rows. This will result in the lice being 
buried in the ground and destroyed. If 
the soil is dry and hot those lice that 
are not buried will be killed by the dust 
closing their breathing pores. The treat- 
ment should be repeated every week or 
more often, until the crop is picked, and 
is only possible where peas are sown in 
rows far enough apart to allow of the 
passage of the cultivator. Another method 
is to drag long shallow pans in which 
floats a film of kerosene down the rows 
and brush off the lice into it. On the 
terminals the lice will often escape such 
treatments and spraying with whale-oil 
soap will destroy many of these. The 
wild legumes harboring the lice in win- 
ter should be destroyed if practicable. 
BEAN 
The Bean Aphis 
Aphis rumicis 1 
This is a small black plant-louse of 
European origin. The nymphs or ‘pupae 
have a conspicuous row of white spots 
on the body. The aphids cluster about 
the terminal leaves and stalks of the 
English bean and often attack the pods. 
The life history is somewhat similar to 
that of the Pea Aphis. The winter eggs 
are laid on shrubs such as the snowball 
plant, the lice migrating in spring to the 
bean, dock and other plants. The aphis 
can be controlled by spraying with whale- 
oil soap (4 pounds to 100 gallons water) 
combined with tobacco extract (Black 
Leaf “40”, 1 to 2,000) or with flour paste 
and tobacco extract. 
CRUCIFEROUS CROPS 
The Cabbage Aphis 
Aphis brassicae L. 
This grayish-green mealy aphis occurs 
all over the United States on cabbages, 
turnips and related plants cultivated and 
wild. The winter eggs are deposited on 
the leaves, the lice hatching therefrom 
in early spring. In the southern states 
and in California viviparous lice may be 
found throughout the year. 
Control 
The refuse of the crop should be de- 
stroyed in the fall. By destroying wild 
mustard and wild radishes in the vicinity 
of the cultivated crop migratory infesta- 
tion will be prevented. The lice can 
also be controlled by spraying with whale- 
oil soap 1 pound to 6 gallons of water 
or with a 7 per cent kerosene oil emul- 
sion. 
The Green Peach Aphis 
Myzus persicae Sulz. 
During the greater part of the year 
this pest may be found on a number of 
vegetables such as cabbage, turnip, cel- 
ery, spinach and lettuce. It may be con- 
trolled in the manner advised for the 
Cabbage Aphis. See under Peach. 
