266 Miss Haviland, The bionomics of Aphis 



The bionomics of Aphis grossulariae Kalt., and Aphis viburui 

 Schr. By Maud D. Haviland, Bathurst Student of Newnham 

 College. (Communicated by Mr H. H. Brindley.) 



[Read 17 February 1919.] 



Aphis grossulariae Kalt. is a serious pest 'of currant and goose- 

 berry bushes in this country. It attacks the young shoots in May, 

 and when present in numbers, it distorts them to such an extent 

 that growth ceases and a dense cluster of leaves is formed, under 

 which the aphides swarm. 



The bionomics of this aphis are incompletely known. It appears 

 on red currants in May, and remains there until the middle or end 

 of July. The sexuales have never been found. In 1912 Theobald 

 (Journ. Econ. Biol., vol. Vli. p. 100) first pointed out its resemblance 

 to Aphis viburni Schr., a common species, which is found on the 

 guelder rose ( Viburnum opulus) in spring and summer, while the 

 sexual forms have been recorded from the same plant in the autumn. 

 Aphis viburni has a very characteristic appearance, owing to the 

 row of lateral tubercles on the abdomen. Such tubercles are not 

 very common among the Aphidinae, but they are prominent like- 

 wise in Aphis grossulariae. In fact there seems to be no structural 

 difference between the two species; though in spirit specimens, the 

 guelder rose aphis frequently stains the alcohol dark brown, while 

 the currant form has no such property. 



In May 1918, I had under observation some red and black 

 currant bushes, and two guelder rose shrubs, which all grew close 

 together. Early in the month all were free from aphid attack, but 

 on May 31st three colonies, each consisting of a single winged 

 female with a few new-born young, appeared on the guelder roses, 

 and the same evening four sprigs of currant were likewise each 

 infected. During the following week, numerous other winged forms 

 appeared both on the guelder roses and on the currants. The 

 method of attack was the same in both cases. The migrant crept 

 into the axil of a leaf, and from thence her progeny gradually spread 

 up the stem and along the midrib. About the same time, I found 

 a Viburnum tree swarming with winged females of Aphis viburni 

 in a shrubbery a hundred yards away; and as these were in- 

 distinguishable from the migrants on the Viburnum and currants, 

 I have little doubt that this was the source of infection. 



Assuming that A. viburni and A. grossulariae are identical, I 

 began experiments to test how far the host plants were interchange- 

 able. Unfortunately, owing to heavy rains, the experiments with 

 the original winged migrants were all inconclusive, and during 



