136 GARDENING INDOORS AND UNDER GLASS 
great extent, exterminate them with a fine brush 
or feather dipped in alcohol, coal-oil or kerosene, 
any of which, if applied directly to them, will kill 
them on the spot. 
Scale. The scales infesting house plants are of 
two kinds. The more common is the brown scale, 
which has a hard, slightly convex, circular shell, one- 
quarter of an inch or so in diameter. The white 
scale is much smaller, and soon forms quite dense 
colonies. Both attack the thick-leaved, smooth- 
barked plants, such as palms, ferns, lemons, and 
abutilons. They do not appear to be doing any 
damage, but invisibly suck the juices of the plant. 
They should be destroyed at once. This is accom- 
plished by the use of fir-tree-oil soap, whale-oil soap, 
or kerosene emulsion and a stiff brush. 
Thrips. ‘These do not often appear in the house, 
but may where plants are crowded in a shady place. 
They eat the substance of the leaves, leaving only 
the skeleton structure. They are small, about a 
quarter of an inch long, and brown or Dlack. 
Aphine, kerosene emulsion or Paris green (one 
teaspoonful to twelve quarts of water) will keep 
them quiet. 
Root Aphis. Sometimes the leaves of a healthy 
plant will begin to look sickly with no apparent 
cause. It may be found upon examination that the 
blue root aphis is at work, clinging in clusters to 
the rootlets. Remove and wash away the soil, and 
