No. 4.] GYPSY MOTH — APPENDIX. 401 



We incline to the belief that this compound plays a most 

 important role in the economy of the insect, in connection 

 with the digestive process and also in the changes taking 

 place in the pupal state. It seems probable that the phos- 

 phate of potash bears a somewhat intimate relation to the 

 development of the reproductive system, since eggs of both 

 fertilized and unfertilized female moths contain large quanti- 

 ties of this compound (Nos. 19, 20, 21). It also occurs in 

 the thick fluid ejected by newly emerged imagoes (No. 18). 



Relation to Insecticides, 



In connection with the discovery of the source of the alka- 

 linity of the digestive fluids of gypsy moth larv^, two lines 

 of insecticide experiments suggest themselves : 



1. To introduce into the digestive system of the larva 

 some substance that shall be inert in neutral or weak acid 

 media, and which shall react with phosphate of potash, liber- 

 ating an effective poison. 



2. To obtain a substance that, when taken into the di- 

 gestive system of the insect, shall precipitate the phosphoric 

 acid, thus destroying its function and preventing the assimi- 

 lation of albuminous food materials. 



