135 
or some other, soap. Whale-oil soap should be used as directed 
on page 120 for plant-lice. Other soaps, preferably “tak-a-nap” or 
“ivory,” may be used with success—dissolving 1 pound in 6 to 
8 gallons of water—and are preferred to the whale-oil soap for 
some plants on account of the disagreeable odor of the latter. In 
spraying it is necessary to reach the under side of the leaves, for 
the liquid is effective only when it comes in contact with the in¬ 
sects. 
The Orchid Isosoma 
Isosoma orchideariim Westw. 
The Chalcididce , to which family the orchid Isosoma belongs, 
were long believed to be merely parasitic upon other insects, but 
it has been proven by entomologists that the species under dis¬ 
cussion, as also other Isosomas, are phytophagous—plant-feeders 
—and often very destructive to cultivated crops. The orchid 
Isosoma was first described in England in 1869, where it was 
probably introduced on Cattleyas from South America. The first 
recorded date of its presence in the United States seems to be 
1889, when the editors of “Insect Life” determined as probably 
of this species an Isosoma found infesting Cattleyas recently im¬ 
ported from the tropics, presumably from New Granada, the in¬ 
formation and specimens having been received from Mr. Albert 
P. Morse, of South Natick, Mass.* 
This insect has occasionally come to our notice as an orchid 
pest in Illinois during the past few years, the first office record 
for it being in 1904, when infested plants were received at the 
State Entomologist’s office from Mr. R. H. Warder, Superin- 
Fig 50. Orchid bud 
injured by larvae of 
Orchid Isosoma, Iso¬ 
soma orchidearum. 
Fig. 51. Orchid Isosoma, Isosoma orcludearum , 
adult. Length about one seventh inch. 
*The Orchid Isosoma in America. Insect Life, Vol. II, Nos. 7 and 8, 
Jan. and Feb., 1890 [written Dec. 3, 1889I, pp. 250-251. 
