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. 



BEA> 



The Beau Aphis 



Aphis rumicis L. 



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. 



CBCCIFEROrS CROPS 



The Cabbage -\phis 



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. 



rill- (iri'CM Peacli Aphis 



Mi/zus pfrsicae 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 tor the 

 Cabbage Aphis. See under Peach. 



