DETERMINATION OF TEMPERATURES FATAL TO THE 
POWDER-POST BEETLE, LYCTUS PLANICOLLIS LE¬ 
CONTE, BY STEAMING INFESTED ASH AND OAK LUM¬ 
BER IN A KILN 1 
By T. E. Snyder, Entomologist , and R. A. St. George, Assistant Entomologist , 
Forest Insect Investigations , Bureau of Entomology, United States Department 
of Agriculture 
INTRODUCTION 
Previous preliminary experiments conducted to determine temperatures fatal 
to Lyctus “powder-post” beetles in the dry kiln have indicated that it is neces¬ 
sary to attain a high temperature for a short period, that is, where the humidity 
does not reach the saturation point, a temperature of 180° F. must be main¬ 
tained for at least one-half hour after the ordinary kiln-drying operation. 2 There 
are objections to subjecting wood to such high temperatures, especially where 
great structural strength is demanded in its subsequent use, as in the construc¬ 
tion of airplanes, for it is likely to weaken the wood fibers as well as to cause 
discoloration. With these disadvantages in mind, and the knowledge that it 
is more economical to steam infested lumber in a kiln at a low temperature for 
a short period than at a high one after the longer period of kiln drying, it was 
decided to conduct some experiments by subjecting lumber to live steam at 
lower temperatures for short periods with a saturated atmosphere, to obtain 
the range of temperatures fatal to the powder-post beetles. Through the 
courtesy of officers of the United States Navy Department, Bureau of Construc¬ 
tion and Repair, and the Naval Aircraft Factory at the navy yard, League 
Island, Philadelphia, Pa., a series of cooperative experiments along this line 
was conducted in November and December, 1923, and in January, 1924. 8 
MATERIAL TREATED 
The material used in these experiments consisted of infested ash and oak 
lumber. The former had been piled for nearly 10 years in the open where it 
was exposed to attack by the southern powder-post beetle, Lyctus planicollis Le 
Conte. The larvse of this beetle had practically ruined the entire sapwood, 
rendering it unfit for any use other than fuel. All of the stock was of high-grade 
material. The ash lumber, being the more seriously damaged and the more in¬ 
fested with insects, was the wood principally used in the experiments. 
THE KILN 
The kiln used is of the water-spray type and its dimensions are approximately 
60 by 14 by 14 feet. Live steam is admitted into it through two pipes, l£ inches 
in diameter, running lengthwise through the center. Along the upper side of 
these pipes, at intervals of 12 inches, there are holes one-fourth of an inch in 
1 Received for publication Apr. 22, 1924—issued Nov., 1924. 
2 Snyder, T. E. high temperatures for the control of lyctus “powder-post” beetles. Jour. 
Forestry 21: 810-814. 1923. 
3 Special acknowledgment should be made to Capt. Q. N. Rock, Bureau of Construction and Repair, 
Navy Department, Washington, D. C., A. N. Miller, mill foreman, Naval Aircraft Factory, Philadelphia, 
Pa., and C. C. Shackford, Naval Aircraft Factory, whose hearty cooperation have made these tests possible. 
Journal of Agricultural Research, 
Washington, D. C. 
( 1033 ) 
Vol. XXVIII, No. 10 
June 7,1924 
Key No. K-133 
