February, '16] SOMES: SOLAXUM INSECTS 39 



SOME INSECTS OF SOLANUM CAROLINENSE L., AND THEIR 

 ECONOMIC RELATIONS 



By M. P. Somes 



Solanum carolinense L., or, as it is commonly called, "horse nettle," 

 is among the most common weeds of Missouri, as also through a large 

 part of the United States. It is in close botanical relationship with a 

 large number of cultivated plants as tomato, potato, peppers, and 

 tobacco. It is congeneric with Solanum rostratum Dunal, the Buffalo 

 bur, from which we have, by transfer of food plant, one of our most 

 serious pests of potato, Leptinotarsa decimlineata Say. 



During our field studies we noted a series of very interesting insects 

 on the horse nettle. Recalling the natural transfer, mentioned above, 

 from an insect beneficial to man feeding on and destroying a noxious 

 weed, to a serious pest feeding on an important cultivated plant, we 

 were led to test transfers of certain of these insects. The dividing 

 line between beneficial and injurious insects is determined by man's 

 interpretation of the insect's activities. A large number of insects are 

 feeders on varied plants, sometimes even in different families, so that 

 a form of injurious status in one locality may possibly be reckoned as 

 beneficial in another. During the summer of 1914, I noted a natural 

 transfer of this sort which resulted in a harmless species suddenly 

 developing into a pest inflicting serious injury to tomato. This was in 

 the case of Jalysus spinosus Say, a common and widely distributed 

 Berytid bug, heretofore considered as of no economic importance. 

 The data concerning this bug have already been published (Mo. State 

 Fruit Exper. Station, Bui. 24, pp. 16-17) but may be briefly summa- 

 rized here. In July, 1914, a lady living near St. Louis wrote me that 

 her tomatoes were being seriously injured by what she surmised was a 

 mosquito. Visiting her place, I found numerous specimens of this 

 slender, mosquito-looking bug. The injury is due to the puncturing 

 of the fruit stems and the ovaries of the flowers, the common result 

 being that the stems die beyond the puncture and the flowers when 

 injured soon blacken and die. We have noted this injury at various 

 times but thought it due to some form of tomato blight. In the Cal- 

 ifornia Monthly Bulletin for July 1914 the following note occurs: "At 

 this season of the year many tomatoes fail to set fruit. Vines blossom 

 well and appear thrifty. However, the blossoms, after hanging on the 

 vines for a time, fall off, leaving a part of the peduncles attached to the 

 stem. The cause is a fungus which causes late blight of potato and 

 fruit spot of tomato." This description is exactly typical of the in- 



