320 Phylum Arthropoda 



Family aphididae 



A USEFUL CAGE FOR REARING SMALL INSECTS ON 



GROWING PLANTS* 



IN THE rearing of aphids and their parasites and scale insects for the 

 past two years, the writer has found a specially designed cage of sheet 

 celluloid very satisfactory. Any cage for rearing these insects must allow 

 for a free circulation of air, permit the entrance of light, and not cause 

 a concentration of heat or moisture. Still another feature bears consider- 

 able importance when dealing with small insects, and that is the absence 

 of any cracks or niches in which the insect may hide or escape. 



The simplest and most suitable form of cage is the cylindrical type 

 made by bending together the edges of a rectangular piece of celluloid and 

 sealing them with 95% alcohol. Ventilation holes of any size and posi- 

 tion on the sheet, may be cut in before bending. After the edges are 

 sealed together and the cylinder is formed, the ventilation openings and 

 one end opening are covered with fine cheesecloth or voile shellacked on 

 the celluloid around the edges of the openings. The cage is now ready 

 to be placed over the plant, usually a small one in a pot. In order to 

 hold the cage securely in position and provide a smooth white surface on 

 the bottom of the enclosure about the plant, melted paraffin is poured on 

 the soil around the plant, and the open end of the cage set down into 

 it after the edges have first been given a thin coat of vaseline to prevent 

 the adherence of the paraffin. Thus treated the cage may be lifted 

 free when the paraffin cools, leaving a smooth tight groove into which 

 the edges just fit and prevent the escape of any insect when the cage 

 is in place. Entry for the introduction or removal of material is easily 

 made by tearing back a corner of the cloth ventilator, or lifting up the 

 cage from its paraffin base. 



Sheet celluloid is a very satisfactory material with which to construct 

 small cages for a portion of a plant like a small twig, or a part of the sur- 

 face of a leaf or fruit on which it is desirable to confine small sedentary 

 insects such as scales and aphids. In these small cages, ventilation may 

 be secured by punching small holes in the celluloid with a fine needle. 

 Shellac was found useful in joining together the sharp edges of the cage 

 and sticking it to the plant surface. This material soon drys, with a 

 hard surface so that it will not entangle the insects, and yet remains 

 soft enough to prevent cracking and breaking apart. 



Cages constructed from sheet celluloid are as transparent as glass, and 

 do not "sweat" like the glass cages. They may be made any size 



♦Abstracted from an article in Ohio J. of Set. 23:201, 1923, by E. A. Hartley, 

 N. Y. State College oj Forestry. 



