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 

 foUo-^t^ing 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 woidd appear preferable, where the de- 

 struction of these inS'ects 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 b}^ frequent examina- 

 tions of the infested trees. The ver}^ 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, 

 Lombardy 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 be necessary for the man handling the nozzle to climb 



[Cir. 121] 



