256 



LEAF-MINING INSECTS 



as the larva proceeds downward and increases in size. 

 Frequently the larva suddenly changes to the opposite side 

 of the leaf so that the mine is no longer visible on the upper 

 surface, thus presenting a broken appearance. The color 

 of the mine is white and shows plainly on the green leaf es- 



Fig. 80. The iris leaf-miner, Agromyza laterella. 1, outer leaf of iris 

 showing the characteristic mines made by the larvae; 2, full grown larva; 

 3, egg; 4, adult 9 ; 5, leaf bundle cut to show the course of the larva as it 

 mines down towards the new forming leaf. (After Claassen.) 



pecially on the low T er part of the leaf, which in the iris, is of 

 a purplish color. The larva proceeds downward just about 

 as rapidly as the new leaves are formed and comes out of 

 the leaf bundles and pass on, thus being in a situation where 

 the tissue is newest and most tender. Sometimes, however, 

 the larva may remain in an outer leaf and mine the entire 



