226 SCALE-INSECTS, BARK-LICE, MEALY-BUGS. 
The same remedies which are applied against the next 
species, will keep it and all other scale insects in check. Where 
only small potted plants are attacked, the entire plant should be 
immersed in a weak solution, (1 to 14), of kerosene emulsion 
or whale-oil soap. A thorough spraying with the same mate- 
rials, to be followed by a spray or wash of pure water, to re- 
move the emulsion, is also effective. On a large scale fumiga- 
tion with hydrogen cyanide will kill all insects. 
Aspidiotus perniciosus Comst. (The San Jose Scale). 
This most destructive species has been found but once in 
our state, and was promptly destroyed with the trees, and as 
all the neighboring trees in the infested orchard were killed since 
by frost, none of the insects could survive. But they can exist 
in Minnesota, hence we have to be on guard against their in- 
troduction from other states. A full account of this insect was 
given by the author in the Twenty-sixth Annual Report of the 
Minnesota State Horticultural Society, which is repeated: 
“It seems that this scale was first noticed in 1873 at San 
Jose, Cal., which fact gave it the name under which it is now 
so well known. It spread rapidly until 1880, when Prof. Com- 
stock discovered and collected it in Santa Clara county, and de- 
scribed it in the Annual Agricultural Report for that year as 
Aspidiotus perniciosus. He selected this specific name because 
he found it the most pernicious scale-insect found at that time; 
nor could a better name be proposed at this date, as it is by all 
means the worst insect which ever threatened our orchards. In 
1892 the insect was discovered in the vicinity of Las Cruces, 
N. M., upon apple, pear, peach, quince and rose. In 1893 
specimens were found at Charlottsville, Va. Soon afterwards 
it was discovered in many orchards in Florida, Maryland, New 
Jersey, New York and Ohio, and in many other’states. In No- 
vember, 1895, it was reported in twenty states, and at the present 
time it is doubtful whether there is a single state in the Union 
that is not more or less infested in some orchards, while some 
of them are fairly alive with it. 
The following description of the insect is taken from a 
paper published by the Division of Entomology: 
“The San Jose Scale belongs to the same group of scale 
