April, ’24] GUYTON: ORIENTAL FRUIT MOTH in PENNSYLVANIA IN 1923 259 
tainer for the gas should not be deep, as the deeper the crystals from the 
top of the soil the slower will be the generation of the gas. 
Laboratory experiments continually show that the gas is liberated 
at about the same rate in both sandy and loam clay soils. Under 
ordinary room conditions paradichlorobenzene gas killed all larvae as 
far down as one foot below the soil level within a period of three weeks. 
Tests in the laboratory have also repeatedly shown that the higher the 
moisture content of the soil and the lower the temperature, the slower 
is the action of the gas on the borer. A detailed account of the results 
obtained from the first year’s work with paradichlorobenzene in Georgia 
will be found in Department Bulletin 1169, which was recently issued 
as a report of progress. 
Vice-President S. B. Fracker: The next paper is by T. L. Guyton. 
ORIENTAL FRUIT MOTH IN PENNSYLVANIA IN 1923 
By T. L. Guyton, Pennsylvania Department of Agriculture , Harrisburg 
During the season of 1923 the Oriental Fruit Moth (Laspeyresia 
molesta Busck) caused a heavy loss to fruit growers in the southeastern 
comer of Pennsylvania. Reports show the insect to have been present 
before 1923, but not numerous enough to cause commercial loss. 
In 1921 the Bureau of Plant Industry made a survey of two of the 
counties now heavily infested, and in none of the several peach orchards 
examined was the presence of the moth suspected. One report in 1922 
showed the moth to have been established at one point. No doubt the 
moth was present in many other places, but no out-standing damage was 
noted. 
In 1923 estimated losses varied thmout the area of infestation. One 
peach grower reports a loss of seventy-five percent of his crop, or about 
twenty carloads. His was the heaviest loss reported. Nearly all other 
reports gave about twenty percent as the loss. Quince fmits found in 
the infested area were entirely destroyed. This .fruit is a favorite food of 
the larvae. 
Only a fragment of the life history of the moth was observed. A 
definite brood of adults was evident the last week of August. These 
moths produced the brood of larvae which caused the heavy loss to 
Elberta peaches. It was difficult to find larvae about peach trees on 
October first, but quinces contained many larvae, and several larvae 
were found in cocoons about the quince trees. Active larvae were 
found in fallen quinces as late as November fifth. 
