294 
the threads are secreted are not evident. Eyes lighter in color than in preceding 
stage. Surface of skin delicately microscopically shagreened. Legs extremely short. 
Rostral filaments short. 
Other stages not observed. 
EXPERIMENTS WITH INSECTICIDES. 
A series of careful tests was made with various standard insecticide 
mixtures to determine the best means of destroying the scales by win- 
ter treatment. The first of the 
series were with the substances 
which have proved most successful 
in California in the treatment of 
the Pernicious Scale (Aspidiotus 
pemiciosus), which, in habit and 
difficulty of treatment, is not unlike 
this newly-imported one. The 
lime-sulphur-salt mixture and the 
winter resin wash were first experi- 
mented with, the latter being 
applied at the strength used in the 
California experiments, and also at 
double that strength. The applica- 
tions were made January 31, 1894, 
the day being a clear and warm 
one, and the trees were liberally 
treated, so that they were thor- 
oughly wetted. The weather con- 
tinued warm after the applications, 
and occasional light rains fell. 
Examination on February 6 showed that so far no injury whatever had 
resulted to the scales. The rains had not been sufficient to wash from 
the trees the lime which adhered from the lime-sulphur-salt treatment. 
On March 7 the lime sulphur-salt treatment still indicated no results in 
the destruction of the scales. The resin wash at the standard strength 
had resulted in the death of about 20 per cent of the scales ; at double 
the standard strength, in the death of about 50 per cent. Examined 
April 2, the ratio of injury in the case of the resin wash applications 
had not changed. A very few dead scales were found on the trees 
treated with the lime-sulphur-salt wash — perhaps about 5 per cent. 
The later series of experiments on a new lot of trees was made with 
kerosene mixtures. Kerosene emulsion made with whale-oil soap and 
diluted five times, the same diluted two and one-half times, and pure 
kerosene were used. These applications were made March 10, and the 
trees were again thoroughly wetted with the insecticides. Examina. 
tion March 15 failed to show any evidence of injury to the scale in the 
case of the diluted kerosene emulsion. A tree to which pure kerosene 
Fig. 17— Diaspis lanatus.- Half-grown female, en- 
larged, with frontal tubercles and greatly en- 
larged antenna above (original). 
