746 General Notes. [September, 
The following recommendations are based on repeated exper'- 
ments in the fie 
1. Applications of Pyrethrum as dry powder—This method is 
Pyrethrum powder, will answer the purpose. If the mixture 15 
applied immediately after preparation, it is always less efficacious 
than when left in a perfectly tight vessel for about 24 hours, oF 
longer, before use. This has been proven so far only with the 
mixture of Pyrethrum with flour, but holds doubtless true also for 
other diluents. Mr. E. A. Schwarz experimented largely under our 
direction with the mixture of Pyrethrum and flour for the Cotton 
Worm, and he found that one part of the powder to 11 parts of flour 
is sufficient to kill the worms (only a portion of the full-grown 
worms recovering from the effects of the powder), if the mixture 
is applied immediately after preparation; but if kept in a tight . 
glass jar for about two days, one part of the powder to 22 parts 
of flour is sufficient to kill all average-sized worms with which 
the mixture comes in contact. For very young cotton were 
mixture of one part of Pyrethrum to 30 parts of flour, and applie 
one day after preparation, proved most effective, hardly any of the 
worms recovering. ; 
An ordinary powder bellows will answer for insects infesting 
dwellings or for plants kept in pots in rooms, or single plants 10 
the garden, but it hardly answers on a large scale out-doors, D&- 
cause it works too slowly, the amount of powder discharge’ 
cannot be regulated, and there is difficulty in covering all parts 
of a large plant. Another method of applying the dry powder y ? 
to sieve it on to the plants by means of sieves, and this fae : 
is no doubt excellent for insects that live on the upper side of the 
leaves. For large, more shrub-like plants with many brnee 
and for insects that hide on the underside of the leaves tls 
advantage that, if the plants are high enough, the powder can oh | 
applied to the underside of the leaves. (7a de continued.) 
