ILLUSTRATIONS. 



PLATES. 



Page. 

 Plate I. Fig. 1. — Early Johnson grass heading and blooming on wet banks of 

 sewage canal, San Antonio, Tex. Fig. 2. — Rubbish left 

 by removal of sorghum shocks in a field near San An- 

 tonio, Tex. 56 



II. Fig. 1. — Harvested field of sorghum near San Antonio, Tex., show- 

 ing scattered seed heads. Fig. 2. — Harvested field of 

 sorghum near San Antonio, Tex., in which the sorghum 

 midge is hibernating. Fig. 3. — Fence line bordering a 

 sorghum field near San Antonio, Tex., allowed to grow 

 up in Johnson grass 58 



TEXT FIGURES. 



Fig. 20. Sorghum heads: Partly destroyed by English sparrows, infested by 



sorghum midge (Contarinia sorghicola), healthy 40 



21. Base map showing present distribution of the sorghum midge 42 



22. Growing sorghum head, bagged and tagged after natural infestation by 



the sorghum midge. 43 



23. Breeding cage suspended over growing sorghum 44 



24. The sorghum midge (Contarinia sorghicola): Adult male and details.. 45 



25. The sorghum midge: Adult female and details, eggs, larvae, pupa... 46 



26. The sorghum midge: " Cocooned larvae," or hibernating form 48 



27. Sorghum heads, showing four successive stages in the opening of the 



sheath or ' ' boot " 50 



28. Sectional views of the sorghum seed during the flowering stage. 51 



29. Aprostocetus diplosidis: Adult female 56 



30. Aprostocetus diplosidis: Adult male 56 



31. Tetrastichus sp.: Adult female 57 



IV 



