920 FIFTH REPORT OP THE ENTOMOLOGICAL COMMISSION. 
Larva.— Body swollen on the thoracic segments, and elao a little humped on the 
eighth abdominal segment. Head held down in a sphinx-like attitude, smooth and 
■ n. Body pale green, like a cedar leaf 
in hue, and so mottled and marked with 
yellowish green ae t<> resemble the leaves 
of the oedni with their yellow-lined scales. 
A br oken dorsal yellowish line, and a 
latero-dorsal line ol* larger yellowish spots. 
On each side of each segment are two longi- 
tudinal yellow spots with a lateral one 
between them. A lateral row of faint 
yellowish patches. Length, - 
8. Phytoptus thuja Garman. 
According to Mr. H. Garman (in 
Forbes's first report on the injurious 
insects of Illinois) this mite occurs 
on the leaves of the American arbor 
vita?, Thuja occidentalis Linn., in 
summer, and in the buds and under 
the leaves in winter. 
u In the latter part of the summer 
of 1880 my attention was called by 
Prof. S. A. Forbes to the diseased 
condition of arbor vita? hedges in 
and about Normal, 111., and upon 
searching the trees this Phytoptus 
was found creeping about the leaves. 
I was inclined at the time to refer 
the coudition of the hedges to in- 
juries inflicted by the mites earlier 
in the season, for they were not suf- 
ficiently abundant at the time the 
examination was made to cause 
serious inconvenience to the plants. 
Since then the trees have regained 
their usual thrifty appearance, and 
the mites, although still present on 
them at all times of the year, have 
not been more abundant at any time 
than they were when first discovered. 
The Phytoptus of the arbor vitoe 
spends the winter in the buds and 
under the margins of the leaves. It 
can be secured in midwinter by bring- 
ing infested twigs into a warm room.*' 
Adults of this ruite measure from .005 to .0065 inch in length, with the greatest 
rse diameter about .009 inch. They are whitish and semi-transparent. Of 
Fig. 306.— Phytoptus thujee (ventral view) ; a, 
iotrum : b, labium : c. ehelicene ; d. appear- 
ance of joints seen on the rostrum ; «, tarsal 
claw : /. feather-like tarsal anpendage ; g, 
one of the first pair of hairs on under side 
• t-phalothorax ; h. one of the second par 
of hairs on the under side of cephalothorax : 
i. genital plate ; j, abdominal Backer.— After 
Garman. 
