356 Phylum Arthropoda 



be removed so that the water of metabolism may escape and thus mold 

 be avoided. Some boxes may be retained in the warm room for more 

 rapid growth of caterpillars and to obtain a further supply of moths. 

 Larvae pupate in cocoons in the cereal or on the cover of the boxes. 

 Moths will emerge in four or five weeks after the two weeks' inspection. 



If the boxes are placed in a cool room after the two weeks' inspec- 

 tion, pupation is delayed but growth continues so that the caterpillars 

 attain much larger size. Boxes may be placed in a refrigerator, 5 or 

 6° C, and used when desired. 



Dangers. Rats or mice, if present, will gnaw into the boxes, eating 

 cereal and caterpillars. 



Beetles or mites may infest the cereal and eat the moth eggs. Habro- 

 bracon or other parasitic wasps may attack the caterpillars. Protozoan 

 and other diseases may infect the caterpillars. All of these dangers may 

 be avoided by using clean cereal, by using new boxes or by returning 

 the boxes to the warm room only after sterilizing in a hot oven, and by 

 removing from the warm room all cultures showing any signs of infec- 

 tion. 



"The White Plague." Chalky, opaque, white caterpillars are full of 

 Coccidian spores, which may be seen as fusiform bodies if the cater- 

 pillar is macerated on a slide and placed under a microscope. 



"The Black Death." Black spots may appear on the caterpillar 

 or the whole body may become black and disintegrate with a foul odor. 

 The infection may appear in one corner of the box while caterpillars 

 in other parts may be unaffected. Wash and sterilize hands before 

 handling cereal in uninfected boxes after contact with infected ones. 



Mold. If cultures become very moldy, caterpillars will not develop 

 well. Avoid by lowering humidity and by disposing of infected cul- 

 tures. When caterpillars were reared in tin boxes the danger from mold 

 was much greater and the water of metabolism sometimes condensed in 

 crowded cultures to such an extent that caterpillars would drown. Even 

 when there was no mold, caterpillars did not grow as well in tin boxes. 



Failure of cultures to set may be due to extreme aridity. It is im- 

 portant to have humidity high when cultures are being started. This is 

 conveniently arranged by means of covered boilers and glasses of water 

 as above directed. In summer and in humid regions it is unnecessary to 

 use boilers. 



