Mylabridae 479 



accurate and preferable method is to pass air through gas washing 

 bottles containing either salt or sulphuric acid solutions. In this case 

 the insects are reared in more or less close contact with an air stream 

 of known humidity. The rate at which the air should be passed through 

 the solutions will depend on many factors, such as the size of the 

 rearing box, the number of insects per container, and the facilities for 

 controlling the temperature of the air. 



All rearing should be done in shallow containers with a comparatively 

 thin layer (^ to 1 inch) of food in the bottom of each. A thin food 

 layer allows the food to come into equilibrium with the environment 

 quickly and to remain so. During their growth and development insects 

 liberate relatively large quantities of water which alter the relative 

 humidity of the environment unless removed as rapidly as liberated. 



The following methods have been used by the writers for rearing 

 large numbers of bean weevils (Bruchus [=Mylabris] obtectus) and 

 mealworms (Tenebrio molitor). The same general methods are ap- 

 plicable for other stored food insects with minor modifications. 



Bean weevils were reared on red kidney beans since it has been 

 found* that this bean variety apparently furnished the optimum food 

 as measured by the most rapid growth with the least mortality. The 

 cultures were started at weekly intervals by placing 500-1000 eggs in 

 pint jars containing about an inch of red kidney beans and covered 

 with cheesecloth or wire screening of 20- or 24-mesh. These containers 

 were placed at a temperature of 25 C. and a relative humidity of 

 75-80%. In this way new batches of adults were obtained each week. 

 The bean weevils, upon emerging, were separated from the beans by 

 sifting through an 8-mesh wire screen. The weevils were then placed 

 in special oviposition cages. These cages consisted of pint cardboard 

 containers with the bottoms pushed out and replaced by 20-mesh wire 

 screening. This size allowed the eggs to drop through readily, but kept 

 the bean weevils in the cage. The cover of the cage was also made of 

 wire screening to provide proper aeration. Another cover on the bottom 

 of the cage served to collect the eggs. The cage contained about a 

 dozen red kidney beans as a stimulus for oviposition. Large numbers 

 of clean eggs may be obtained in this way with relatively little trouble. 

 The eggs may be removed at definite intervals, thus providing a source 

 of eggs of known age. 



Under the conditions described above, one generation of bean weevils 

 will require about 40 days from egg to egg stage at 25 C. and 80% 

 relative humidity. If the relative humidity is the same and the tem- 

 perature is raised to 30 C. only 30 days will be required. 



* L. Hill and F. B. Maughan. Unpublished work of the Dept. of Entomology, 

 Cornell University. 



