New York AGRICULTURAL ExPpRIMENT STATION. 19 
of the formation of the polar body in the parthenogenetic egg 
have been worked out. 
San José scale-—These investigations may be divided under 
two heads: (1) The development of the insect, and (2) the 
methods of control. During development the insect passes 
through three well-defined periods: (1) The period of activity; 
(2) the period of growth, and (3) the period of reproduction. 
The duration of all of the periods varied greatly with the tem- 
perature. During the active period the larve migrated readily 
over smooth surfaces. Numerous insects, representing five 
orders, were found from time to time with larve clinging to 
them. Ants, bees and wasps apparently do not carry them. 
During the period of growth the scale is formed. The average 
number of young produced per day by female of the fall broods 
was 4 little over two. 
Experiments with kerosene oil, 100° fire test and 150° fire test, 
showed the former to be dangerous to the trees at the lowest 
percentage, when mixed with water, required to kill the scale. 
The latter gave similar results with peach trees and injured plum 
trees to a very slight degree when used strong enough to be 
effective to the scales. Apples and pears were uninjured. Ex- 
periments are also being made with crude petroleum and hydro- 
cyanic acid gas. A fumigator for orchard trees has been devised 
which was successfully used in the experiments, 
DEPARTMENT OF HORTICULTURE. 
Fumigation of nursery stock.—The best known way of killing 
San José scale on dormant nursery stock is by fumigation with 
hydrocyanic acid gas. This treatment is valuable not only 
against San José scale, but against all scale insects which do not 
winter in the egg stage. It will doubtless also check the spread 
of some other kinds of injurious insects which are liable to be 
distributed on nursery stock: : 
Plain directions for fumigating dormant nursery stock with 
hydrocyanic acid gas are published in Bulletin 174 together with 
