PLANT LICE INJURING THE FOLIAGE 



199 



and kno^vn there as the '' green peach aphis." The Uce migrate 

 in early summer to various truck crops, especially spinach, cab- 

 bage, lettuce, and celery. They are light green or yellowish in 

 color, with darker markings on the abdomen. The head, antennae, and 

 honey tubes are black. This species is never covered with white 

 powdery secretion, hke the cabbage aphis. It is controlled by spraying 

 with a contact insecticide, preferably tobacco extract or 5 per cent 

 kerosene emulsion. In greenhouses this species is found throughout 

 the year, and is a troublesome pest. 



The Melon Aphis, or Cotton Aphis (Aphis gossypii Glov.) 



Melons, cucumbers, cotton, strawberries, and many other plants 

 are subject to infestation by this species of plant louse. It usually is 

 seen in the wingless form, and 

 works for the most part on 

 the under surface of the leaf, 

 which is badly curled by its 

 attack. Tender growing 

 shoots are a favorite feeding 

 place. 



The wingless louse is dark 

 green, varying to yellow. Its 

 legs are light yellow, and its 

 honey tubes are black, long, 

 and tapering. Its length is 

 one fifteenth of an inch. The 

 young stages are similar, but 

 are smaller and wingless. 

 Winged individuals are de- 

 veloped whenever the lice are 

 compelled, tlirough lack of 

 food or removal of a crop, to 

 seek new feeding ground. 

 Consequently attack may come on suddenly and unexpectedly. The 

 full life round is not known, and probably the species passes one 



Fig. 248. 



Work of the Melon Aphis. 

 Original. 



