12 
ing dormant period of trees; (2) early during hatching period of eggs, 
and (3) late during hatching period of eggs. The results were not 
entirely consistent, and further experiments are promised. The two 
following points, however, are emphasized: 
(A) Eggs of the oyster-shell scale are unaffected by the application of lime-sulphur 
solutions made previous to the opening of the buds. On trees so sprayed the young 
were killed very soon after hatching. The intervention of rain storms before the hatch- 
ing of the eggs may more or less affect the value of the treatment. 
(B) It is indicated that emulsions of linseed oil and cottonseed oil may be useful for 
the treatment of this insect while in the egg stage and during the hatching period. 
On the whole, therefore, it would appear preferable, where the de- 
struction of these insects alone, is to be considered , to spray as the young 
insects are hatching in the spring. The table of dates of hatching 
given under the remarks on life history for each species will indicate 
approximately when the young insects may be expected to appear, 
but this time may be accurately determined by frequent examina- 
tions of the infested trees. The very small, yellow insects will be 
seen in numbers crawling over the limbs and branches in their efforts 
to find a suitable place for settling. 
The data on the dates of hatching of the two species, considered 
in connection with blooming dates of fruit trees, indicate that for any 
locality the young of both species will have hatched and settled, and 
may be effectively treated during the period of from one to three 
weeks following the blooming period of the apple; and from two to 
four weeks after the period of blooming of the peach. It will be 
preferable, however, positively to determine the time of crawling 
of the young for the particular locality and food plant, by actual 
observations. 
In spraying for the young insects when the trees are in foliage, the 
presence of the leaves will render thorough work more difficult, and 
especial care will be necessary to reach all limbs and branches, treat- 
ing every portion of the tree from top to bottom, as only those insects 
actually hit are destroyed. A weaker wash must also be employed 
than during the dormant season, as will be indicated later under the 
head of formulas, or else injury to the foliage and fruit may result. 
TREATMENT OF SHADE TREES. 
The oyster-shell scale will often require treatment on maples, 
Lombard y and Carolina poplars, ash, and willow. As these trees 
will be rarely sprayed during the dormant period for other scale pests, 
it will be advisable to give the treatment just after the hatching of 
the young, as already explained. Effective spraying of shade trees, 
when these are of some, size, will require painstaking work. In many 
cases it will he necessary for the man handling the nozzle to climb 
[Cir. 121] 
