A. S. HOENE AND 11. M. LeFKOV 'All 



Infestations. 



The following species were used in making infestations: 



1. Aleurodes vaporariorum Westd. 



2. Red Spider, Tetranychus telarins Linn. 



3. Aphis, Rhopalosiphtrm solani Theob. 



4. Jassid, Evpteryx atropunctata Goeze. 



Chlorita viridula Fall (? C. solani Koll.). 



5. Capsid, Calocoris hijnmdatris Fabr. 



Lygus pabidinus Linn. 

 The first three of these, being obtainable early in the year, were used 

 for the first series of infestations, commenced at Wisley on March 22, 

 1912. Jassids and Capsids were not obtainable until June, hence 

 infestations with these insects were not commenced until after the 

 earlier experiments were completed. Parallel infestations, using the 

 above-mentioned insects, were carried out at Chelsea upon the plants 

 raised at Chelsea. 



The conditions under which the experiments with Aleurodes, Red 

 Spider, and Aphis were carried out were as follows: The floor of the 

 greenhouse adjoining the laboratory at Wisley was covered with a layer 

 of garden soil and a number of cloches arranged in rows upon it. Some 

 of the cloches rested directly on the surface of the soil. Under these 

 conditions, if the soil were regularly watered, the atmosphere within 

 the cloches would remain saturated. The remaining cloches were raised 

 above the level of the soil supported on inverted pots so that the air 

 inside the cloche was in communication with the air outside but would 

 be on the whole damper than that of the greenhouse and sometimes 

 saturated. 



Four pots were placed under each cloche. Groups of four plants 

 not covered by a cloche were also stationed on the soil. 



The experiments arranged at Wisley were as follows: 



No. 2. Red Spider. Cloche on inverted pots. Plants watered 

 seldom. 



No. 1. Aleurodes. Cloche on inverted pots. Muslin edging to 

 prevent escape of insects. Plants watered regularly. 



No. 9. Aleurodes. Cloche on soil. Plants watered regularly. 



No. 4. Aphis. Cloche on inverted pots. Plants watered regularly. 



No. 3. Aphis. Cloche on soil. Plants watered regularly. 



No. 5. Aphis. Plants not under a cloche. Watered regularly. 



Ann. Biol, i- 25 



