>» an icy’ Pe 
y, ¥ nF ae ? oi ov ae 
_ 5 e ves Tay reds! 37 
‘ ' 
: ee atic yt 
460 MINNESOTA STATE HORTICULTURAL SOCIETY. = 
\ ; AN a 
SCALES IN MINNESOTA. aaa 
PROF. OTTO LUGGER, MINN. STATE EXPERIMENT STATION, A / 
PTs: 
When we compare the conditions prevailing in Minnesota as far 
as scale-insects are concerned with those in other states, we can be 
but thankful that such insects are at the present time not nearly so ae 
numerous and destructive as they probably will be in the future. : 
This is at least the opinion of the writer, based on long experience, ; 
who—some thirty years ago—had to search long and very carefully rata 
to discover scales to go in the state collection of Missouri. Nor 
were they very abundant and easily found in Maryland twenty years 
ago. Since that time conditions have greatly changed, and scale- + 
insects are now in both the states mentioned more than common. 
In fact, few fruit trees can be found in those states that are not more 
or less badly infested, and the insects are still on the increase, not 
alone in individuals but also in species. In former times economic 
entomologists did not need to worry about such insects and how to 
destroy them; now it is almost their chief work in many states to 5 
study them with a view to discover remedies against them. It is 
frequently claimed that Minnesota is too far north to furnish a suit- 
able home for insects of this character. This would be a very good 
thing, indeed, if such was the case, but all the species that have 
thus far found their way to our state have prospered well, too well 
in some cases. Even the San José scale forms no exception. \ 
Before discussing the different species now found in Minnesota, : 
it will be best to describe in a few words the family of scale-insects, ie 
or bark-lice. They take their first name from the scale-like covering 
with which most species are provided, and the second one from 
their usual place of attachment on the infested plant. Scale-insects 
area very anomalous group of insects, and differ very much in 
appearance, metamorphosis and habits from closely allied families. 
They are very unlike all other insects, and there is a wonderful 
variety of forms within the family, and even the two sexes of the 
same species differ as much in the adult state as members of dis_ 
tinct orders. All, or nearly all, are minute, the scale rarely measur- 
ing more than one-eighth of an inch in size, most of them being 
even smaller. Some of the insects included in this family on 
account of their affinity in structure, though unprovided with a 
scaly covering, grow larger as, for instance, the Cottony Maple-scale 
shown in the illustration. 
The young ofall scale-insects are small and oval lice which run 
about actively for a few hours or days, after which they settle down, 
and by inserting their sucking mouth-parts in the tissues of a plant 
imbibe its sap and commence to grow. Before long there appears 
over their bodies a slight covering of a waxy or cottony substance, 
which serves both for protection and concealment. Soon afterwards 
the larve commence to secrete a firm, papery, shield-like covering, 
different in the different species, which in time becomes the scale 
proper. During the completion of this final scale the skin is shed 
once by the males, twice by the females. Both sexes lose their legs 
and feelers in shedding the skin and become thus mere immovable 
