86 NEW YORK STATE MUSEUM 
temperature in the spring checks the flow of sap and, following an 
application of oil, is very liable to result in greatly increased pene- 
tration by the insecticide, sometimes with disastrous results. It 
is very likely that the apparent immunity of different varieties 
depends in considerable measure upon seasonal variations in the 
pressure of the sap, due to an early or late ripening of the wood 
and possibly to differences in the penetrability of the bark. 
Record of injury following applications of a miscible oil. The 
following records are not intended to be exhaustive and are made 
public simply to establish the fact that serious injury may follow 
the use of oil preparations upon dormant trees. 
In June Igi1 our attention was called to the serious condition 
of many hard maples in Mount Vernon, sprayed the preceding 
spring with a miscible oil. Some of the trees most infested by in- 
sects, it is stated, were sprayed March 24th and again May 2oth. 
There were some 2136 hard and soft maples which received this 
application. The soft maples were practically unharmed, while 
many of the hard maples, in fact all marked as having been sprayed, 
which we examined June 2oth, showed evidence of recent ser- 
ious injury, many being practically dead. This was true of small 
trees three inches in diameter, as well as of maples some eight 
inches in diameter, all, with very few exceptions, appearing 
as though they had been in full vigor the preceding sea- 
son. Trees on one side of the street or on one block were affected, 
while unsprayed trees of the same variety on the opposite side of 
the street or on adjacent blocks were in normal condition. In 
some instances the damage was limited to_ limbs most easily reached 
by the usual type of spraying outfit. We were unable to find suff- 
cient evidence of injury by insect pests or damage following gen- 
eral adverse conditions to account for the sudden death of so many 
trees in a closely restricted area. Additional details of our findings 
at that time are given in the report for last year (27th report of 
the State Entomologist, New York State Museum Bulletin 155, 
pages 88-92). 
Personal observations during July and August of last season 
(1912) showed that practically all the trees noted as being badly 
injured the preceding year, had been removed and replaced by 
small trees. We were informed that 449 maples had been: reset. 
Furthermore, some of the trees less seriously injured in 1911 
showed dead limbs or patches of dead bark, and the prospect is 
