12 Arinals Entomological Society of America [Vol. XI, 



Puparia of these larvae were first observed on July 25, 1916. 

 In cases where larvae reached maturity in the early or mid- 

 summer, the puparia were always found at the base of one of 

 the large outer leaves. Here the larva mines more to the 

 center of the leaf-base, so that the mine is well within the 

 tissue of the leaf and not visible from the outside. A somewhat 

 enlarged excavation is made here, the larva assumes its position 

 for pupation, and transformation occurs. The base of the leaf 

 around the puparium swells just a little, thus showing a slight 

 tendency toward gall-formation, (Plate II, Fig. 7). 



Later in the fall the leaf is often found split open at the 

 base, thus exposing the puparium. These puparia remain in 

 this condition till the following spring. 



Owing to the fact that oviposition stretches over a con- 

 siderable length of time, (adults were seen around the iris plants 

 for three or four weeks) different stages of larvae were found in 

 the iris all summer. 



The larvae in the fall of the year are always found mining 

 on the innermost leaves of the leaf-bundle, and there in the 

 very latest formed leaf, just as the plant ceases growth before 

 the winter sets in, the larva enters and transforms into the 

 puparium. Plate II, Fig. 9, shows the larva as it enters this 

 inner leaf and Plate II, Fig. 10, shows the leaf after the larva 

 has entered and pupated. 



The iris plant does not die down completely in the fall, 

 but the center remains alive, and usually on each side of the 

 plant are formed offsets which produce the new plants the 

 following spring. These offsets then may be regarded as new 

 individuals, while the center represents the overwintering form 

 of the old plant. Both center and offsets are protected from 

 exposure by the old leaves which in the spring gradually drop 

 to the ground and disintegrate. Plate II, Fig. 1 shows a plant 

 with several offsets. 



In the spring when the plant resumes its growth, it is the 

 little leaf in the center which contains the puparium, that 

 causes the characteristic gall. The second leaf, crumpled, 

 stands there as an indicator, showing that the gall was formed 

 while the second leaf was still rapidly growing. 



