PEA AND BEAN INSECTS 71 



the anteniiffi arc carried back over the head. In this stage the 

 insect is shiggish and takes no food. In four to fourteen days, 

 depending on the season, the nymph transforms to the adult. 

 In CaUfornia there are seven generations a year, the first and 

 last being small. In the early part of the season the thrips 

 are most abundant on their wild food plants. They do not 

 become abundant on beans until later in the season, although 

 a few may be found on this crop from the time it first comes up. 



Control. 



The injury caused by the bean thrips may be lessened by 

 clean cultivation to destroy the weeds on which the insect 

 breeds. Early planting and thorough cultivation will tend to 

 produce a rapid and healthy growth ajid render the plants 

 more able to withstand injury. In the garden the thrips may 

 be controlled by spraying with "Black Leaf 40" tobacco ex- 

 tract, 1 part in 800 parts of water in which enough soap has 

 been dissolved to produce a good suds. 



Reference 

 U. S. Bur. Ent. Bull. 118. 1912. 



The Pea Aphis 



Macrosiphum pisi Kaltenbach 



Without doubt the most serious insect enemy of the pea is 

 this large green plant-louse. The insect was undoubtedly intro- 

 duced into this country from Europe. Although there is evi- 

 dence that it was present here as early as 1878, it did not attract 

 attention as a pest until 1899 when there was an extensive and 

 highly destructive outbreak in the Atlantic states, most serious 

 in Virginia, Maryland, Delaware and New Jersey. The losses 

 occasioned by this insect in the Atlantic states during the years 

 1899 and 1900 have been estimated at $7,000,000. While the 

 pea aphis has not maintained this rate of destructiveness in 



