158 DISEASES OF THE SWEET PEA 



greenhouse, too, the prevalence of the aphis 

 is always correlated with an abundance of 

 mosaic, as well as with weak spindly 

 plants. 



The sweet pea aphis is very prolific. It 

 is estimated that each individual if al- 

 lowed full sway would be the progenitor 

 of 423,912 aphids in one season. These 

 lice, however, are fortunately kept in check 

 by natural enemies. The list of insects 

 known to feed on the sweet pea aphid 

 includes seven species of lady beetles, three 

 species of Syrphus or lace wing fly, a sol- 

 dier beetle, and a few minute four winged 

 Hymenopterous parasites. 



Lady Beetles. Hippodamia converg- 

 ens. It behooves every grower to learn to 

 recognize this friendly insect. Its eggs 

 are laid in clusters, found everywhere on 

 board fences or on trees. The eggs are 

 small, salmon color, and pointed at both 



