Mar. 4, 1918 Toxicity of Organic Compounds to Insect Eggs 



583 



for periods from i to 120 seconds, eggs of different ages being used. 

 The results are given in Table II. This table shows that in general with 

 compounds of very low boiling points the freshly laid eggs or those con- 

 taining embryos only partially developed were more easily killed than 

 those in which the embryo was fully developed. Gortner and Banta (5), 

 in working with the toxicity of certain phenolic compounds to amphibian 

 eggs, found that the youngest eggs were more susceptible than the older 

 eggs. This may be due to disturbances in the permeability of the egg, 

 and compounds with low boiling points such as ether would have more 

 influence on the permeability than compounds with higher boiling points. 

 With an increase in the boiling point it was found that the eggs in which 

 the embryo was fully developed were most easily killed. Compounds 

 with very high boiling points, such as nicotine and kerosene, often 

 remained on the eggs and killed the larvae in the act of hatching. It 

 seems that compounds with high boiling points are not able to penetrate 

 the egg as readily as compounds having low boiling points. In general a 

 slightly longer exposure to the chemical will result in the death of a larger 

 number of eggs. 



In these experiments the writers they have been unable to remove 

 compounds of high boiling points from the surface of the egg without 

 injury to the egg, and, hence, have no data as to the length of time 

 necessary to kill with these compounds. 



Table III. — Toxicity of kerosene to eggs of various ages 



Age of eggs. 



1 day 



2 days 



3 days 



4 days 



Freshly laid 



Slightly developed 



Well developed 



Spiracles visible through shell . 



Within I day of hatching 



Within 2 days of hatching 



Within 3 days of hatching 



Within 4 days of hatching 



100 



100 

 100 



33 

 o 

 100 

 100 

 100 

 100 



Percentage hatching after dipping for- 



I min. sniin. loxnin. is jnin.i aojnin. Brand 



13 

 100 

 100 



100 

 100 

 100 

 100 

 100 

 o 

 100 



o 



100 

 100 

 100 

 100 

 o 



100 

 100 



Unknown. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 

 Pearl oil. 



Do. 



Do. 



Do. 



A special study was made of the action of kerosene on the eggs, inas- 

 much as it was a high-boiling-point compound which did not always 

 kill. The results of dipping eggs of different ages in kerosene are given 

 in Table III. Eggs i day old in general did not hatch after being dipped. 

 Eggs classed as freshly laid, which may have been i or 2 days old, hatched 

 in every case, while eggs with well developed or fully developed embr3'os 

 failed to hatch. This is interesting in that by killing the young eggs it 



