74 
PSYCHE 
[August 
further growth of the shoot is not absolutely prevented. The gall indeed lies near 
the border-line between a true gall and such pseudo-galls as wood-inhabiting beetle 
larvae produce when Ijoring i)i slender twigs. The larval ehainber is small and 
irregular in form. Typically, the shoot swells and beeomes a hollow, long-oval gall 
sueh as is sliown in the figure. All forward growth of the shoot as a whole is stopped, 
but lateral reserve buds may grow and develop leaf rosettes. More rarely, only the 
proximal end of the shoot is affected, forming a short-oval or globular gall and the 
terminal bud develops normally. The long-oval galls usually measure 2 or ,3 
centimeters. 
In April the gall of Eutreta sparsa was found to be of full .size, but the contained 
larva was still small. Tlie larva grew rapidly during May and ])upated early in June. 
This stage lasted a little over two weeks, the flies emerging about the 20th of the 
month. 
Agromyzid.ve. 
Agromyza magnicornis Loew. (Figure 3). When the leaves of the Blue Flag, 
Iris, are a few inches tall, the outermost leaf of the leaf-bundle is often found to be 
modified in so definite a manner that the resulting structure can be called a “gall.” 
The leaf ceases to grow. The upper part Irroadens and also becomes thickened over 
a limited area, so that there is a vei-y characteristic bulge on either side of the blaile. 
If this be cut into, — even early in the Spring, — a small, oval, laterally eompre.ssed 
jniparium is found. The flies emerge from these puparia about the last of May. 
This, 1 believe, is the first gall-like structure to be flescribed for an Agromyzid, 
though the point of attack, the leaf, agrees well with the habits of other members of 
the Family, many of which mine the foliage of plants. As in the Trypetid galls 
already described it seems here that the larval life is completed during the previous 
Fall. But I have not as yet obtained data on this point. 
The alteration of the outer leaf not infrecjuently injures the inner or second leaf 
of the leaf-bundle in a consjacuous way. 'I'he tip of the latter becomes caught in 
the malformed groove of the outer leaf and is held fast for a longer or shorter perioil. 
As a result the rajadly growing leaf is bent, and although it ultimately becomes free, 
yet the twisting ])roduces a noticeable series of wavy folds. 
1 am indebted to i\Ir. C. W. Johnson of the Boston society of natural history 
for identification of the Trypetids and to Mr. D. W. (Mquillett for that of the Agro- 
myza. 
Clark University, Worcester, Mass. 
