28 MISSOURI BOTANICAL GARDEN BULLETIN 
remove dust and soot which so frequently accumulates on 
the leaves, to the injury of the latter. This practice besides 
Den beneficial greatly improves the appearance of the 
plants. 
Insect and Fungous Diseases.—Of these two classes of plant 
diseases, only the former, the insect diseases, are ordinarily 
of much importance in the home; conditions in the house 
are not usually favorable for the development of fungous - 
diseases. Insects injurious to plants may, however, multiply 
rapidly under the conditions ordinarily obtaining in houses, 
and cause serious injury to a great variety of plants. Among 
the most troublesome are the so-called scale insects attack- 
ing palms, ferns and many other plants. hile there are 
many species of scale insects attacking plants, those usually 
infesting house plants are quite large, looking like miniature 
tortoises or footless lady-bugs tightly adhering to the surface 
of the leaves. Owing to the armor-like protecting layer over 
the scales, the latter are not readily killed by the ordinary 
mild insecticides. Control is most easily effected by scraping 
or brushing off the insects, after which the leaves should be 
washed with alcohol or soap and water, and thoroughly 
rinsed in cold water. Plant lice or aphids are another fre- 
quent source of trouble, and should be watched carefully 
because of the amazing rapidity with which they multiply. 
Tobacco liquid, which may be obtained from florists under 
a variety of trade names, will usually free plants from these 
. The liquid is best applied in the form of a fine spray. 
ther injurious insects of house plants are usually of such 
size that hey can be best controlled by the simple expedient 
of picking them off and destroying them. 
PLANTS TO GROW 
For success in growing plants indoors much depends on 
the proper choice of varieties. As might be concluded from 
what has been said, plants which can be grown successfully 
in the average house must, in general, be such as can endure 
a dry atmosphere, usually a high temperature, and frequently 
inadequate light. The plants which most nearly meet these 
unusual requirements are certain tropical forms with more 
or less thick, leathery leaves like the palms, rubber plants, etc. 
—plants ordinarily classed as foliage plants. Among the 
large number of palms useful as indoor foliage plants, the fol- 
lowing may be mentioned as among the best: Phoenix 
Roeblinii, Cocos Weddelii, Corypha australis, Chamaer 
humilis, Rhapis flabelliformis, Kentia Belmoreana, 
Noresteriana, Phoenix Rupicola, Seaforthia elegans, Areca 
lutescens, and Latania Bourbonica—one of the fan palms. 
