68 REPORT OF No. 19 



Tulip Tree Midrih Gall (C ecidomyia tulipifera). 

 Hollow swellings, varying from .5 to 2.5 cm, in length, by 3-4 m.m. in 

 width, on the midrib and lateral veins of the leaves, of the tulip tree. Mono- 

 thalamous. Occurs on Tulip tree (Liriodendron tulipifera) . Not common. 



Spircea Pod Gall (C ecidomyia salicifolia) . 



The leaves are folded in such a way as to assume the appearance of a 

 pod. The pod is formed by the folding of the leaf along the midvein, and 

 the bulging out of the sac thus formed, the outer margin of which is closely 

 united. The pods vary in size, the largest being about five-eighths of an 

 inch long. Occurs on Spiraea {Spircea tomentosa). Common. 



Willow Club Gall (C ecidomyia rigida). 

 This gall is formed on the lateral shoots of the Bush Willow, an en- 

 largement of the whole stem, tapering from the centre to both ends. Occa- 

 sionally galls are found having terminal shoots growing from them. The 

 gall is about three-quarters of an inch long. Occurs on several epecies of 

 Bush Willow (Salix sp.). 



Goldenrod Bunch Gall {C ecidomyia solidaginis) . 

 It is found on the main stalk of Goldenrod. An apical gall which pre- 

 vents the natural elongation of the stem. This unnatural accumulation of 

 several hundred leaves into a globular mass is the result of injury to the 

 terminal bud and consequent arrest of growth in length. Occurs on Golden- 

 rod (Solidago sp.). Very common. ^ 



Goldenrod Ball-Gall (Trypeta solidaginis). 

 This is a globular ball-like enlargement of the stem of Solidago, about 

 2i cm. in diameter. Pithy in structure, hypertrophy monothalamous, the 

 central cell irregular in shape and containing a large fat larva which de- 

 velops into a fly with banded wings. It is green in summer and woody in 

 winter. Occurs on Goldenrod (Solidago sp.). Very common. 



Vein Gall on Oak (C ecidomyia quercus-majalis) . 

 These galls are produced along the veins or the under side of the leaves 

 of the Red Oak. They are, narrowly oval, inflated galls much like the 

 Cecidomyia pudibunda on Carpinus. The surface of the gall is netted with 

 veins. The wall is quite thin. The opening to the gall is upon the upper 

 side of the leaf, and runs the full length of the gall. The gall is hollow 

 and the interior wall smooth. Green or brown in color. Occurs on Red 



Oak (Quercus rubra). Not common. / 



Op 

 Hickory Nut Gall (Cecidomyia caryce-nucicola). 



A malformation of the nut produced by a Cecidomyiid, resulting in the 

 formation of large irregular knobs all over the husk of the nut, containing 

 thickwalled cells. Hypertrophy polythalamous. Occurs on Hickory (Hic- 

 oria Alba). Not common. 



Alder Bud Gall (Cecidomyia serrulata). 



A rounded monothalamous bud gall, a deformation of the terminal bud 

 of the Alder. Occurs on Alder (Alnus sp.). Not common. 



Midrib Gall on Virginia Creeper (Cecidomyia sp.) 



This gall is green and succulent. It forms along the midrib of the leaf 



and occasionally along the side veins. It is flat and generally double, that 



is, on both sides of the vein. It is on the under side of the leaf and is really 



an enlargement or thickening in a fold on the leaf near the midrib. It 



