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reddish lice may be seen crawling in all directions about the 
trunks and branches of infested trees. 
The Hubbard formula for kerosene-emulsion mentioned 
above, is given in the article about leaf-lice. 
The willow or cottonwood-scale is illustrated in Fig. 66, 
Plate 16. 
WHITE-SCALE OF THE CACTUS. bs 
(Diaspis cacti Comst.) 
One of the most conspicuous and beautiful of the green-house 
scales is the round or white-scale of the cactus. The scales 
possess two different forms, of which the female scale is about 
one-sixteenth of an inch in diameter, circular, with a dark- 
brown center. The male scale is about half as large, yellow- 
ish-white with a dark spot at one end, and a small ridge run- 
ning the length of the scale. These scales are often very 
closely crowded, and if very numerous may cause the death of 
the plant. 
The use ofa stiff brush with soap and water, or a wash of 
kerosene-emulsion, are the most useful remedies. 
An illustration showing this peculiar scale will be found in 
Fig. 67, Plate 16. 
THE ELM-TREE WHITE-SCALE. 
(Chionaspis americana Johnson. ) 
Many of the fine elms in the vicinity of St. Paul and Minne 
apolis are infested with small white scales closely resembling 
those on cottonwood, but less conspicuous, as the bark of the 
elm is spotted with white and therefore better adapted to con- 
ceal them, (Fig. 68, Plate 12). They are present on both the 
trunk and twigs. The female scale is white and pear-shaped, 
while the male is smaller and more slender, and has a slight 
longitudinal ridge. This scale is not known to be destructive 
at present, but notice is given so that it may be recognized 
should it ever become so. 
THE ECCENTRIC SCALE OF THE ELM. 
(Aspidiotus ancylus Put.) 
A careful examination of our silver-maples and elms some- 
times reveals the presence of a small gray scale, which so 
