A. S. HoRNR AND H. M. Lefroy 385 



Calocoris fulvo-maculafus de G. Carpenter {Report for J 896) refers to 

 C. bipunctatus F. and to Lygus pabulinus L. {Report for 1911). Theobald 

 also refers to L. pratensis L. {Report for 1904, p. 63) and there are a 

 number of references to these species by continental authors. So far 

 as we are aware, these describe attacks observed in the field, not 

 symptoms definitely produced experimentally. 



Field observations on Jassids. 



Potato fohage was marked with white spots caused by Jassids in 

 many localities in 1912, and these insects were in every case observed 

 in the leaves. The spots were usually scattered and infrequently 

 united to form moderately large areas, and did not involve the whole 

 leaf surface, giving it a whitish appearance, as may frequently happen 

 in the case of the rose and various fruit trees. 



The very characteristic white spots can be seen in the field on potato 

 at once and Eupteryx is in all cases found there. Similar spotting can 

 be seen on rose, plum, cherry (Fig. 14) and apple in the early stages of 

 Jassid attack, but in 1913, 1914 the attacks became so severe that the 

 whole leaf became yellow. 



Such attacks are well known in England and have been described 

 by Theobald and by Curtis. 



Summary, 



1. Definite and similar symptoms apart from any other cause were 

 obtained as the result of infesting young plants raised from seed of the 

 President variety of potato with Red Spider, Aleurodes, Aphis, Jassid, 

 and Capsid under various experimental conditions at Wisley and 

 Chelsea as follows : 



{a) Red Spider. — Leaves became mottled, plant turns brown and 

 dies. 



(6) Aleurodes. — Effect gradual, plants weakened but did not die. 



(c) Aphis. — Leaves with discoloured veins, brown and dead leaf- 

 ends, yellowing and death of the plant. 



{d) Jassid. — White spots, plants did not die. 



(e) Capsid. — Dark brown blotches on leaves and young growth, 

 veins darken, young leaves and shoots killed rapidly. 



These symptoms did not develop in the controls except in the cases 

 where the control plant became infested by the particular insect 

 experimented with. 



