114 



INSECTS INJURIOUS TO VEGETABLES 



does severe damage, hence little precaution need be observed in 

 the treatment of it, further than to destroy all affected pods, 



Fig. 69.— Gray hair-streak, a, b. Butterfly; c. larva; d, pupa; e, egg, much en- 

 larged; others somewhat enlarged. (Howard & Chittenden, U. S. Dept. Agr.) 



that the insect may not develop and do injury later and in after 

 years (fig. 69). 



It may be successfully controlled by a spraying with an ar- 

 senical on its first appearance. 



The Pea Aphis {Ncctarophora destructor Johns.). — Until the 

 year 1899 peas grown in the United States sulYered little injury 

 from insects other than the pea weevil. In that and the fol- 

 lowing year, however, this crop was badly injured by the pea 

 aphis, which caused enormous losses in our principal pea- 

 growing regions, especially where peas are grown for canning. 

 It was, in fact, one of the most destructive of all insects that 

 ravaged crops in the United States at that time. 



This aphis is of unusual size among those found in gardens, 

 and the largest green species which attack the pea and related 

 plants. The length of the body of winged viviparous females 

 is about 3/16 inch, and the total wing expanse about 4/10 inch. 

 The general color of both the winged and apterous or wingless 

 forms is uniform pea-green, the same as its food plants. As 

 to whether this insect is native or of foreign origin there is 

 till some doubt. 



