BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 13 
of more than 1 million moths were obtained. Because of these records 
it was possible (1) to double the allotment (to 200,000 charges) of 
attractant material for research purposes, (2) to allot 17,000 charges 
for surveying more than 7 million acres during the summer of 1919, 
(3) to stock-pile attractant for future use, and (1) to discontinue col- 
lections of pupae for 1 year since a new chemical treatment keeps the 
material potent for several years. 
An innovation of the season was the testing in New England of 
such attractant from gypsy moths obtained by the Bureau from North 
Africa. This material proved satisfactory, and assures the availabil- 
ity of attractant should the rapidly increasing use of DDT in New 
England prevent large collections of pupae in the near future. 
Active constituent of gypsy moth attractant studied 
Progress has been made in the investigation of the chemical nature 
of gyptol, the active constituent of the gypsy moth attractant. By 
preparing a /?-phenylazobenzoyl ester from the neutral portion of the 
benzene extractive of the female terminal segments and subjecting it 
to chromatographic separation on a magnesium carbonate column, a 
fraction can be obtained which contains all the gyptol. Testing of 
the attractiveness of the various fractions has been greatly expedited 
by the development of a laboratory technique for rearing male gypsy 
moths eggs collected in the fall and kept in cold storage. Products ob- 
tained in chemical studies can now be tested during the winter, whereas 
it formerly was necessary to hold all materials for field tests during the 
following summer. 
Preventing spread of gypsy moths through regulatory activities 
Substitution of annual nursery-wide DDT spraying for individual 
plant inspection or treatment was approved on April 15, 1949, as a 
basis for certification of plants under gypsy moth-quarantine regula- 
tions. All nursery plantings for which certification is desired are 
sprayed. Nursery surroundings are also included when necessary to 
prevent reinfestation of the premises. The spray is applied at the 
rate of 2 pounds of DDT per acre. Mist blowers delivering 2 gallons 
of DDT concentrate per acre or hydraulic sprayers applying the same 
amount of DDT in 600 gallons of solution have been used successfully 
in these operations. Spraying between the time of the spring egg 
hatch and pupation of the caterpillars qualifies the nursery stock for 
certification from the following July 1 until the next year's egfr hatch, 
when spraying must be repeated. In June 1949 four large establish- 
ments sprayed in this manner 200 acres of nursery areas. 
Adjustments have been made in a number of fumigation methods 
and procedures. Revised instructions, issued September 28, 1918, pre- 
scribe a slight increase in methyl bromide dosage for fumigation of 
Christmas trees, evergreen boughs, lumber, cordwood, quarry products, 
scrap iron, sawdust, shavings, wood chips, excelsior, and excelsior 
waste. Fumigation of such articles in boxcars is now restricted to cars 
of all-steel construction. Tighter sealing of all cracks through which 
the gas might escape is also required. Provision for the introduction 
of methyl bromide gas through a ^-inch T-nozzle propped against the 
