SOUTHERN GREEN PLANT-BUG. 25 



strong contact insectide or by using a gasoline torch. Even if it 

 were found necessary, in order to kill the nymphs and adults econom- 

 ically, to use measures that would injure the plants, the operation 

 might prove profitable in areas where serious damage occurs. Where 

 the plants have not been grown especially as trap crops the destruc- 

 tion of the nymphs and adults when they congregate in large numbers 

 would assist materially in reducing their destructiveness. 



SUMMARY OF CONTROL MEASURES. 



It would seem that spraying with a contact insecticide is not prac- 

 tical, unless emplo} T ed in connection with trap crops where injury 

 to the plants by the insecticide is not of importance. While it is 

 possible to use mixtures strong enough to kill even the adults, the 

 injurious effects of the insecticide upon the plants, as well as their 

 present cost, would have to be considered. 



The writer is inclined to agree with Watson (14) that hand pick- 

 ing is the most satisfactory control measure where valuable vegetable 

 crops are seriously attacked, but for less valuable crops it is question- 

 able whether this could be profitably done. 



The fact that the adults congregate on turnip and mustard late 

 in the fall in Louisiana suggests that a few of these, or other plants 

 upon which they congregate, might be grown to serve as a trap crop. 



GENERAL SUMMARY. 



A pentatomid bug, Nezara viridula L., here given the common 

 name of the southern green plant-bug, causes severe injury to culti- 

 vated crops in the southern portion of the Cotton Belt of the United 

 States. Among the vegetable and truck crops injured are tomato, 

 beans, Irish potato, sweet potato, okra, mustard, and turnip. 



The species is widely distributed over the world and attacks a 

 great variety of plants. 



The adults and nymphs cause injury by inserting their beaks into 

 the plant tissue and extracting the juices. Young growing shoots 

 and developing fruit are most seriously injured. 



Life-history studies have been carried on at Baton Rouge, La., in an 

 insectary where the average maximum and minimum temperatures are 

 slightly higher than those given by the United States Weather Bureau 

 for the same locality. One female began egg-laying 19 days after be- 

 coming adult, although the average length of this period for the several 

 females under observation was about four weeks. The number of 

 eggs deposited by different females varied greatly. Some laid no 

 eggs, while one deposited 240 and had 77 well-developed eggs in the 

 ovaries at death. The eggs are placed in clusters, and in the field 

 they have been found always on the underside of leaves. These 

 clusters were made up of from 36 to 116 eggs. 



