324 Phylum Arthropoda 



presented a difficult problem. Most aphids develop well in confinement, 

 and do not often try to leave a favorable plant. The old device of a 

 cloth topped lantern globe on a flower pot containing the food plant 

 answers the purpose fairly well. Several modifications have been used. 

 Glass lamp chimneys with the top closed with cloth or stoppered with 

 cotton have been successful ; light weight mica chimneys have been un- 

 satisfactory outdoors because they blow off easily. If plants in the flower 

 pot are small, observations may be made easily, and special precautions 

 may be taken to make the cage tight and to keep the soil smooth and 

 bare. If it is desired to find molts and dead insects without fail, paper 

 may be placed on the soil, or melted paraffin may be poured over the soil 

 to form a temporary floor. 



Plants should be of a favorable species; aphids will not thrive on all the 

 plants they are known to infest. They should also be in a thrifty growing 

 condition; new and vigorous seedlings are especially favorable. Trans- 

 ferring has been done with a small camel's hair brush; in transferring, the 

 worker should be sure the aphid has a good foothold on the plant before 

 leaving it. Some aphids, especially small nymphs, will fail to get back 

 on the plant if they fall on the soil. 



References 



For the culture of Toxoptera graminum see p. 397. 

 For the culture of Macrosiphum cornelli see p. 499. 



CULTURE OF APHIDS 



A. Franklin Shull, University of Michigan 



THE breeder of aphids needs to remember that many species will 

 feed only on certain plants. They wander from any others on which 

 they may be placed and starve rather than accept them. No artificial 

 method of feeding them has yet proved feasible. There are, however, 

 a number of cosmopolitan species which feed on many different plants. 



If a phenomenon is to be studied which is exemplified in only one or 

 a few species, the investigator's first question is whether he can supply 

 the food plant for the duration of the study. Aphids feeding only on 

 a deciduous tree or shrub are not usually suitable for such studies. If the 

 problem is one of general physiology or of a wide spread anatomical 

 feature, the cosmopolitan species are available. One who is not well 

 acquainted with the group would do well to consult a taxonomist, to learn 

 the accepted food plants, before essaying a breeding problem with any 

 given species. Once the suitable plant or plants are known, the possibility 

 of providing them for the length of time required will be easily ascer- 

 tained. 



Some of the common vegetables and garden flowers may be grown 



