308 Scientific Proceedings^ Royal Dublin Society. 



It must be noted, however, that, owing to technical difficulties, where so many 

 breeding cages are under observation, it is not possible to breed out all the 

 offspring. The table below must therefore be taken as only expressing the 

 general trend of the appearance of winged and apterous viviparous females. 



(e) Successive Geiierations of Aphis rumicis on Broad Beans. 

 (Variety : Sutton's Prolific Longpod.) 



Broad Beans B. — 16. 6. 20. Infected with 2 a. v. $ ? ; offspring of winged 

 migrants on Broad Beans. 12. 7. 20. A large number of aphids present, a. v. 

 S ? and w. V. ? S . 



Broad Beans B^.— 10. 7. 20. Infected with 4 a.v. ? $ from B. 19. 7. 20. 

 Offspring adult. 26. 7. 20. One adult w. v. ? ? , remainder a. v. ? S , large 

 size, infestation heavy ; killed off the plant and infected a new plant with 

 four of the a. V. ? ?. 10.8.20. Many a. v. 5 ? andw. v. 2 ? present. 



Broad Beans B^.— 10. 7. 20. Infected with 4 w. v. ? 2 from B. 19. 7. 20. 

 Some a. V. 2 ? adult, large size. 26. 7. 20. Infestation heavy. 



Broad Beans B3.— 25. 7. 20. Infected with 6 a. v ? 2 from B^. 4. 8. 20. 

 A.v. 2 2 andw. V. 2 2 present. 12.8.20. Many winged forms present. 



Broad Beam B4.— 6. 8. 20. Infected with 6 a. v. 2 2 from B3. 27. 8. 20. 

 Infestation heavy, a. v. 2 2 and w. v. 2 2 present ; killed off plant and in- 

 fected a new plant with some of the apterous and winged forms. 14. 9. 20. 

 Many a. v. ? 9 and w. v. ? ? present ; killed off the new plant. 



Broad Beans B5.— 14. 9. 20. Infected with 5 a. v. ? ? from B4. 11. 10. 20. 

 A. V. ? ? ; w. V. 9 ? , a few ^ S , and two sexual ? ? present. 



Broad Beam Bj.— 11. 10. 20. Infected with 10 a.v. ? ? from B5. 29. 10. 20. 

 A few a. V. ? $ , many w. v. ? 2 , and several c^ (J present. Development slow 

 owing to low temperature in glass-house. 



Note. — From B, onwards the plants were kept in a warm green-house, the 

 temperature varying as shown in chart, text (fig. 2). 



Broad Beans B,.— 29. 10. 20. Infected with 5 a. v. ? ? from Be. 18. 11. 20. 

 3 w. V. 9 9 adult, many immature winged forms, large size (sexuparae alatae). 

 26. 11. 20. All the aphids are w. v. 2 2 (sexuparae), and a few ^ ^ . 



Broad Beam Bs. — 23. 11. 20. Infected with one of the a.v. 2 mothers on 

 B,. 5. 12. 20. Four w. v. 9 ? and one a. v. 9 produced. Allowed w. v. 9 9 

 to produce on the same plant. 26.12.20. The w. v. 9 9 have produced 

 oviparous 9 9 . 



Broad Beam Bg. — (Two plants.) Infected one plant on 19.11.20, and 

 the other on 25. 11. 20, each with one w. v. 9 from B,. Only sexual 9 9 

 produced in each case; hence these are true female-producing sexuparae. 



