INSECTS INJURIOUS TO TOBACCO 



223 



late in the season, it would seem that the moths might be attracted 

 to a trap crop of late corn in the same manner as cotton is pro- 

 tected from it. 



The Tobacco Leaf -miner * 



The larva of a small moth has become quite injurious in part, 

 of North Carolina and Florida by mining the inside of the leafs 

 and is thus known as the Tobacco Leaf -miner. This insect occurs 

 in other parts of the country, but has become injurious only in the 

 states named and in recent years. The injury is done by the 

 larva? eating out irregular patches of the tissue in the leaves, leav- 

 ing only the upper 

 and lower surfaces, 

 the lower leaves 

 being infested the 

 worst. The leaves 

 are rendered unfit 

 for wrappers, split- 

 ting and tearing very 

 easily on account of 

 these blotches. A 

 larva does not con- 

 fine its work to one ^ IG - 1^. Tobacco leaf-rr.iner or split-worm: adult 



moth above; larva below at right; pupa below at 



left, with side view of enlarged anal segment 

 all enlarged (After Howard, U. S. Dept. Agr.) 



place, but makes 

 several mines, and a 

 single larva may thus destroy the value of a leaf for wrapping pur- 

 poses. This migratory habit is of considerable importance, as 

 in leaving the old and in making new mines the larvae must 

 necessarily eat a certain amount of the surface of the leaf, and 

 can thus be killed by an arsenical spray. The life history of the 

 insect is not completely known, but as only about twenty days 

 are required for all its transformations, several broods probably 

 occur during a season. The original food-plant of this pest has 

 been found to be the common horse or bull-nettle (Solarium 

 carolinense), which fact further emphasizes the caution already 

 given, to keep all weeds carefully cut down around the tobacco- 

 field, especially those nearly related to tobacco botanically. Many 

 planters destroy the larvae by simply crushing them with the hand, 

 and this can be done quite rapidly, and if done before the mines 

 become numerous should be sufficient to check the injury. 

 * Phthorimcea operculella Zell. Family Tineidce. 



