318 Phylum Arthropoda 



tory. Another method of establishing a colony is to collect the adult 

 psyllids by "sweeping" infested plants with an insect net equipped with 

 a heavy gauze or sheeting bag. For removal to the laboratory the adult 

 psyllids may be placed in a temporary gauze cage, together with portions 

 of a succulent plant, or inside of celluloid cages placed over young potato 

 plants. In the laboratory, the adults may be transferred from the field 

 cages to the rearing cages by means of a common aspirator. [See p. 46.] 

 Care should be used to prevent aphids from entering the rearing cages 

 with the psyllids or upon host plants. Plants upon which potato psyllid 

 eggs have been laid may be potted and moved to the laboratory, if desired. 

 A high nymphal mortality usually occurs when the leaves are picked off 

 and become dry before the eggs hatch or when the egg stipes are shaved 

 from the leaves and the eggs placed upon moist blotting paper inside of 

 petri dishes. 



Cages. Several types of cages have been found to be suitable for the 

 rearing and handling of potato psyllids: 



1. Large gauze cages, built to the width of laboratory windows, and about 20 inches 



deep, were found to be excellent for rearing potato psyllids. West windows 

 were best in the winter and shaded east basement windows during the hot 

 summer weather. 



2. Medium to large gauze cages with a wooden bottom and frame work. Cages 12 



to 18 inches wide, 16 to 24 inches long, and 16 to 20 inches deep were well 

 adapted to rearing the psyllids. The front end consisted of a celluloid obser- 

 vation sheet which covered approximately the upper Ys to V2 of the frame; 

 to this was cemented (with acetone) a gauze flap extending approximately 2 

 inches beyond the margins of the end. This gauze flap serves as a door, being 

 fastened snugly with thumb tacks, except when potted plants are to enter 

 or leave the cage. Small slits, which may be kept plugged with cotton, 

 admit the 6 to 8 mm. aspirator, for capturing adult psyllids, and the glass 

 tube, used with a funnel to water the host plants. 



3. Other suitable breeding cages consisted of round or square gauze cages, with a 



glass or celluloid panel and with a round opening in the bottom to fit upon a 

 flower pot containing a host plant. 



4. Celluloid cages of various sizes to fit 6- to 8-inch pots. Cages fitted with a top 



and two side ventilators of gauze usually were satisfactory, but moisture 

 would occasionally collect, resulting in the drowning of adult psyllids. 



5. Small clip cages, made of 4-dram homeopathic vials, with the closed end cut off, 



flanged, and covered with gauze, made satisfactory cages for one to several 

 psyllids. These cages were held in place by means of a piano wire spring, 

 a flat metal disc covering the top. To prevent the death of contained portions 

 of the leaf, it was necessary to move such cages daily. 



6. A similar cylindrical cage, made of fine screen wire or celluloid and set into a 



small, thin, padded board, with a matching, padded board to fit on the 

 opposite side of the leaf, avoided this difficulty. Such cages were held together, 

 without excessive pressure, by means of rubber bands around the ends of the 

 small boards. (Cages 5 and 6 are similar to those used on beet leaf hopper 

 investigations.) 



7. Individual nymphs may be reared, when under constant observation, by placing 



