February, ’18] 
LOVETT: CALCIUM ARSENATES 
57 
President R. A. Cooley: We will pass to the next paper by 
Mr. Garman. 
NOTES ON THE LIFE-HISTORY OF LASPYRESIA 
MOLESTA BUSCK 
By Philip Garman, College Park, Md. 
(Withdrawn for publication elsewhere) 
President R. A. Cooley: If there is no discussion we will pass to 
the next paper on the program, “The Calcium Arsenates and Their 
Efficiency as Insecticides,” by Mr. Lovett, of Oregon. 
THE CALCIUM ARSENATES 
By A. L. Lovett, Entomologist, Oregon Agricultural Experiment Station 
Introduction 
The value of the lead arsenates as a stomach poison for insects has 
been thoroughly established for the past two decades. Just now the 
general advance in price on all commodities due to the war conditions 
has affected this material as well and the report is current that the 
available supply of lead arsenate is limited. This condition makes 
necessary the development of an efficient and practical substitute. 
Calcium arsenate has long been recognized as a cheaper material 
than the lead arsenate, but though numerous sporadic tests have been 
undertaken the general conclusion has been that the material is un¬ 
satisfactory because of too frequent excessive burning. The prevailing 
conditions have revived the interest in calcium arsenate and a number 
of investigators, including ourselves, have begun a study of these 
materials. 
One of the larger commercial spray manufacturing companies esti¬ 
mates the annual production of lead arsenate for spray purposes at 
30,000,000 pounds. This makes the annual cost to the grower about 
$3,600,000 for their poison spray. Calcium arsenate, in which the 
comparatively cheap lime is substituted for the expensive lead, can be 
obtained at one-half the cost of the lead arsenate or effect a saving of 
$1,800,000 annually. This estimate is based on pre-war prices and the 
difference in favor of the calcium arsenate should be even greater now. 
An analysis of commercial samples of calcium arsenate gave a very 
high water soluble arsenic content, and as with most arsenical sprays 
the cause of burning is largely due to the action of the arsenic on the 
