COLLECTING AND PRESERVING INSECTS BANKS. 



115 



number of plants that are eaten generally by a large number of cater- 

 pillars. Polygonum, for example, is noted as a food plant for many 

 Geometridse; lettuce is eaten by many Noctuidao; apple by many 

 Notodontida?, etc. Buds are sometimes split and fed to larvae that 

 issue before the leaves are out. 



In some cases it is better to put a cage over an outdoor plant. A 

 headless keg covered with gauze makes a good outdoor cage. Two 

 or three pieces of willow may be bent over a plant, the ends stuck in 

 the ground, and this frame covered with gauze or netting. Moths 

 and butterflies may sometimes be induced to oviposit in such a cage 

 when they would not in the laboratory. Mr. Fletcher succeeded 

 in getting a few eggs from reluctant females by gently pressing the 

 tip of the abdomen until one or two eggs were deposited. This 

 may be done with specimens that have just died. Outdoor cages are 

 used by the cotton boll weevil investigators and at the gipsy moth 

 laboratory. They arc light frames covered with wire netting, and 

 tall enough for a person to 

 stand in them. Some styles 

 are described in Technical 

 Bulletin No. 12, part 6, 

 Bureau of Entomology, U. 

 S. Department of Agricul- 

 ture. Others may be de- 

 vised to suit special cir- 

 cumstances by any ingeni- 

 ous mind. One may find 

 it advantageous to tie a 

 piece of netting over a 

 branch or twig on a tree or 

 bush outdoors. This is especially useful in getting the insects that 

 are developing within the seeds of plants. 



A breeding cage (fig. 172) used by the California Board of Horti- 

 culture and by the cotton boll weevil investigators is a wooden box 

 lOor 12 inches long and6 to 8 inches wide and of about the same depth. 

 This box is fitted with an inner cover of glass and an outer cover of 

 wood. One can therefore examine the material without permitting the 

 escape of the insects. In one side of the cage several holes are bored 

 and a glass tube fitted into each. The insects will be attracted by 

 the light and come out into the tubes. The tubes can be quickly 

 removed, the hole stopped with cotton, and the insects dumped into 

 a cyanide bottle. For insects that pupate in the soil a layer of sand 

 may be put into the bottom of this box. 



Professor Comstock has devised a root cage, as shown in figure 173, 

 in which to rear and study hypogean or underground insects. The 

 cage consists of wooden ends with glass sides. It is filled with soil, 

 88552— Bull. 67—09 9 



Fig. 172.— a breeding-cage foe parasites. 



