SCALE-INSECTS, BARK-LICE, MEALY-BUGS. 223 
hatch soon after will find a matted, soapy mass surrounding them, 
which ,they can not penetrate. 
“Tf the trees or plants are known to be infested they can 
be winter treated, i. e., cut back, burn cuttings, apply potash 
followed by kerosene or fish-oil soap. : 
“The insect is one that is usually kept in check by natural 
conditions, and becomes injuriously abundant at irregular in- 
tervals only. Even if no treatment is adopted the natural bal- 
ance is soon restored, but not without the destruction or serious 
injury of considerable plant-life.” (Smith). 
No species of the genus Ceroplastes occur in Minnesota. 
SUB-FAMILY DIASPINA. 
In this sub-family the scales are composed in part of moulted 
skins, and partly of an excretion of the insect, but the most im- 
portant character is the peculiar form of the last segment of the 
body, which is furnished with many openings and appendages, 
varying greatly in number and form, thus affording good char- 
acteristics to distinguish between otherwise very similar species 
(consult Fig. 185, b). But to use the characters we have to dis- 
tinguish between the scale of the males and the females. In the 
scale of the fully developed female there are two moulted skins, 
while in that of the male there is but one. 
Prof. Comstock gives the following table to separate the — 
genera: 
A. Scale of female circular with the exuvie either 
central or more or less nearly marginal. 
B. Scale of male but little elongated, with the 
exuviz more or less central; scale usually 
resembling that of the female in color 
SUMED POXCEUR Cs) space tava ctenat coop eos ajote chai: ois Pacman ASPIDIOTUS. 
BB. Scale of male elongated, with the exuviz at 
one extremity. 
C. Scale of male, white and carinated..... DIASPIS. 
CC. Scale of male, not white and with no 
Central Canina: ene oma eo ere eG. : PARLATORIA. 
AA. Scale of female elongated, with the exuvie at 
one extremity. 
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