102 MISCELLANEOUS STUDIES 



one following is probably the same species, and is the one described 

 as Aphis papaveris by Fabricius. The species from Vicia faba is 

 probably the species described as Aphis fabae Scop., which may be 

 synonymous with Aphis eiwnomi Fabr., but again may not be. The 

 author tried a few transfer tests this spring (1917) with the form 

 from Vicia, attempting to colonize it on Hedera helix and on Rumex 

 spp., with negative results. Of course, this does not prove that it will 

 not colonize on these plants, although the author has come to the conclu- 

 sion that the Hedera species is entirely different, being Aphis hederae 

 Kalt. Dr. Patch 16 in her interesting paper on aphid ecology makes 

 the following statement regarding migration tests, which, it seems to 

 the author, it is well to remember when making such tests : 



If an investigator fails in one hundred attempts to colonize thistle with 

 migrants from plum, that will not be a safe reason for him to conclude that he is 

 not working with Aphis cardui, or that this thistle aphid has nothing to do with 

 the leaf deformations of the plum in the spring. It has been my experience that 

 negative data with aphids under such conditions are just no data at all. If the 

 structural characters are such as warrant the migration test in the first place, they 

 warrant a patient continuation even in the face of repeated failures. 



On the other hand (and this is a most encouraging and stimulating circum- 

 stance in connection with aphid migration tests), a single success goes a long way 

 to prove the case. Barring complications, a single success is enough, and repe- 

 titions and verifications are needed only as safeguards in that respect. 



The third description is from specimens taken on Rumex spp. and 

 although slightly different from the one considered as Aphis eiwnomi 

 Fabr., it may be the same, and it may be Aphis rumicis Linn., but of 

 this the author is doubtful. 



In the bean fields of Ventura County, this black bean aphis is very 

 abundant, and often does considerable damage. In May, 1917, the 

 bean plants were just beginning to appear, and as yet were not 

 infested with the aphis. However, the native dock was quite heavily 

 infested. It seems that the aphis lives over the winter on dock and 

 perhaps on other native plants, migrating in the early summer to the 

 beans. Here it lives throughout the summer, returning to dock when 

 the beans have been harvested and the plants plowed under. Horti- 

 cultural Commissioner A. A. Brock, of Ventura County, places great 

 hope in the efficiency of Hippodamia convergens Guerin as a con- 

 trolling factor. In the spring of 1917 he collected a vast number of 

 these ladybird beetles in Sespe Canyon and turned them loose in the 

 bean fields just as the aphids were beginning to appear. At the 

 present time the results are unknown. 



! Patch, Edith M., Concerning problems in Aphid ecology, Jour. Econ. Ent., 

 vol. 9, pp. 44-51, 1917. 



