y) CIRCULAR 523, U. S. DEPT. OF AGRICULTURE 
RESULTS OF TESTS 
In the evaluation of the toxicity of compounds to the newly hatched 
codling moth larva, the experience of the authors indicates that close 
reproducibility in results is not usually obtained, even with a com- 
pound as uniform as lead arsenate. Many factors contribute to this 
variability and, unfortunately, some of the more important ones are 
beyond the control of the investigator. The results given in this cir- 
cular therefore represent only a rough estimate of the toxicity of the 
various organic compounds reported. A more accurate evaluation 
could be obtained only through much more extensive testing. 
Only a comparatively small number of the organic compounds in- 
cluded in this study have exhibited any marked toxicity to the codling 
moth larva. This is evident from a comparison of the results with 
these and with those obtained with unsprayed plugs and plugs sprayed 
with lead arsenate as given in tables 1 and 2, respectively. 
In table 2, in which the toxicological results with lead arsenate are 
given, it will be noted that a lowering of the surface tension of the 
carrier, as with the addition of a very large proportion of ethyl alcohol 
or casein ammonia, led to a reduction in its effectiveness. It should 
be appreciated, how ever, that this does not necessarily follow when 
these or other wetting agents are necessary to obtain a more uniform 
seep en of organic compounds than could be gotten with water 
alone 
With the exception of those tests a lead arsenate in which its effec- 
tiveness was apparently lowered by the presence of too much wetting 
material, this compound generally held the percentage of wormy apple 
plugs to less than 50. 
The results of the tests of organic compounds will be found in 
table 3. 
It will be noted that the compounds listed in this table have been 
arranged in groups. This classification is purely an arbitrary one, 
as it is obvious that some of the materials could be placed in any one 
of several groups. This classification has been used, however, in 
reporting tests of synthetic organic compounds against other insects 
and, for convenience, is used in this work. When sufficient data with 
regard to a particular insect have been assembled, it might be advis- 
able to reclassify certain compounds to show the relationship between 
chemical constitution and toxicity. 
The “standard error of percent wormy” was calculated from a 
generalized standard deviation derived from analyses of variance 
based on survivals in groups of 0 to 10.0, 10.1 to 20, and 90.1 to 100. 
By this method occasional values of 0 and 100 percent are shown with 
standard errors, indicating the probability that the result is not 
exactly reproducible and that in longer series values greater than 0 or 
less than 100 percent would frequently be encountered. Wherever 
the standard error has not been recorded, the test was not examined 
in such manner as would permit of statistical treatment. 
The key symbols necessary to an understanding of the data of the 
tables in this circular are as follows: 
