8 THE SPRING GRAIN -APHIS OR "GREEN BUG." 



TEXT FIGURES. 



Page. 



Fig. 1. The spring grain-aphis {Toxoptera graminum): Winged and wingleaB 



viviparous females and young on wheat plant 12 



2. Map showing the locality from which the spring grain-aphis was re- 



ceived in 1SS2 and the two additional localities where it is probable 

 that it also occurred in injurious numbers in that year: also the two 

 localities where it was found in 1S54 14 



3. Map showing the distribution of the spring grain-aphis in both the east- 



ern and the western hemispheres 17 



4. Map showing the known distribution of the spring grain-aphis in the 



United States and Canada 19 



5. Maps showing areas covered by outbreaks of the spring grain-aphis dur- 



ing the years 1890, 1901, 1903, and 1907 20 



6. The spring grain-aphis : Male and antenna 45 



7 . The spring grain-aphis : Winged viviparous female and antenna 46 



8. The spring grain-aphis : Wingless viviparous female 47 



9 . The spring grain-aphis : Oviparous female showing eggs within the abdo- 



men 50 



10. The spring grain-aphis : Hind tibia of oviparous female 50 



11. The spring grain-aphis : Eggs 51 



12. The spring grain-aphis: Young, first instar 59 



13. The spring grain-aphis: Young, second instar 59 



14. The spring grain-aphis: Pupa of winged viviparous female 60 



15. The spring grain-aphis : Shrunken and nearly spent oviparous female.. 79 



16. The spring grain-aphis: Aberrant female with both eggs and embryos in 



abdomen showing through the body wall BO 



17. The spring-grain-aphis: Aberrant female pupa which produced young. 81 



18. The spring grain-aphis: Shell of egg after young stem-mother has 



emerged 103 



19. Aphidius testaceipes, principal parasite of the spring grain-aphis: Adult 



female, antenna of male, egg i04 



20. Aphidius testaceipes ovipositing in the body of the spring grain-aphis. . . 105 



21. Position of larva of ill testaceipes in the body of wingless adult 



female of the spring grain-aphis, from 11 a. m. to 12.32^ p. m 110 



22. Position of larva of Aphidius testaceipes in the body of the spring grain- 



aphis at the beginn i ng of the change to a yellowish color Ill 



23. Full-grown larva of Aphidius testaceipes taken from body of the spring 



grain-aphis as shown in figure 21 Ill 



24. Larva of Aphidius testaceipes spinning its cocoon in the dead body of the 



spring grain-aphis 112 



25. Larva of Aphidius testaceipes working its way prematurely from the body 



of the spring grain-aphis 112 



26. Full-grown larva of Aphidius testaceipes 112 



27. Pupa of Aphidius testaceipes immediately after pupation 113 



28. Dead "green bug- " ( Toxoptera graminum) showing exit holes of Aphidi- 



us testaceipes 113 



29. The spring grain-aphis: Winged female parasitized by Aphidius testa- 



ceipes 118 



30. Aphelinus mali: Adult and stigmal club 122 



31. Aphelinus nigritus: Adult and stigmal club 123 



32. Aplielinus semiflavus: Adult and sugmal club 124 



33. The spring grain-aphis: Dried remain s from which adult Aphelinus 



nigritus has emerged 124 



34. Megorismus sp. : Male, female abdomen 126 



