GALLS CAUSED BY GALL-WASPS 
45 
cases, etc. That the species is injurious in many instances 
there can be no doubt. It only frequents stub or young 
oaks, not over 3 or 4 feet high. These, when they appear 
in numbers in nurseries, they frightfully distort, and not 
infrequently render saleless.” 
The leaf-rolling saw-fly (Blcnnocampa pusilla ) has of late 
years attacked cultivated Roses in various parts of England, 
in some cases to such an extent that no blossoms were 
produced. 
Cultivated Orchids are sometimes attacked by Isosoma 
orchidearum (see J. O. Westwood’s paper in the “ Gardener’s 
Chronicle,” 1885, vol. xxiv., p. 84, on “Galls on the Roots 
of Orchids ”). The surface of the stem is covered with 
distinct swellings, and exhibits necrosis in irregular patches. 
There are circular or oval holes leading into cavities of 
irregular form. The base of the leaf, and often the floral 
sheath, is thickened and swollen; other parts bear isolated 
rounded swellings. Attacked buds are swollen, globular, 
and thickened. Westwood observed these galls on a 
species of Dendrobium, and Fitch found them on Cattelya 
T riansei. 
