Bui. 329, U. S. Dept. of Agriculture. 



Plate I. 



i-v 4 



Development of Eggs within the Ovaries of Simulium venustum after 

 a Blood Meal. 



Fig. 1. — Condition of ovaries corresponding to stage 1 (without feeding); la, single 

 egg from same, larger scale. Fig. 2. — Condition of ovaries corresponding to stage 2 

 (after blood meal); also internal anatomy of abdomen; ve, ventriculus or stomach; 

 m, m, Malpighian tubes; jp, juncture of Malpighian tubes and location of pyloric 

 valve; i, ileum; c, colon; 7'<7,"rectal glands; od, od, oviducts; a, anus; v, vagina; s, 

 spermathecum; to, left ovary; to, right ovary; t, t, trachea;. Fig. 3.— Condition of 

 ovaries corresponding to stage 3 (after blood meal) ; 3a, single egg from same, larger 

 scale. Fig. 4.— Condition of ovaries corresponding to stage 4 (after blood meal); 4a. 

 single egg from same, larger scale. Fig. 5.— Condition of ovaries after oviposition; 

 5a, large, fully'developed eggs left near oviducts; remainder of ovarv corresponding 

 to stage 1. Highly magnified. (Original.) 



