472 Phylum Arthropoda 



same supply of plant mold, moistened at suitable intervals, normally 

 serves to carry them through the first and second instars. Subsequently, 

 as more food is consumed and as fecal material accumulates, it is 

 necessary to renew the vegetable mold. Vigorous larvae, like those of 

 Euetheola, Cotinus, etc., consume vegetable mold very rapidly. This 

 necessitates frequent renewal, and as this material cannot always be 

 obtained in quantity, it becomes advisable, as the larvae increase in 

 size, to place them in boxes with soil and to add food in the form of 

 wheat grains or corn kernels as needed. In rearing Euetheola, Phillips 

 and Fox (1924) failed to get larvae of the earliest instar to feed on 

 wheat or corn, but these larvae readily consumed the vegetable mold. 

 In later instars, it was found that they fed on corn previously soaked in 

 water. Larvae fed in this double way were carried in considerable 

 numbers from the egg to the pupal and adult stages, which appeared at 

 the same time that these stages appeared in the field. Baerg and Palm 

 (1932) experienced difficulty in rearing Euetheola larvae on vegetable 

 mold alone, but succeeded in rearing them through the first instar in a 

 sandy loam containing humus and other plant debris, to which in later 

 instars sprouted kernels of corn were added. Hayes (1929) found that 

 the larvae of such Scarabaeidae as Ligyrodes and Euphoria, which 

 normally live in manure and other decaying matter, could be success- 

 fully reared by mixing the soil in which they were placed with an equal 

 quantity of manure. 



The temperature range for the normal development of the larva 

 seems to be more restricted than for the egg stage. Ludwig (1928) 

 found that 25° C. (77° F.) was optimum for complete larval develop- 

 ment of the Japanese beetle. Considering the entire larval stage, 

 complete development was obtained only at temperatures between 20 

 and 27. 5 C. (68° and 81. 5 F.). Above and below these points the 

 larvae did not transform to pupae. In his experiments, each instar was 

 able to tolerate a greater range of temperatures. For instance, the 

 first instar larva was successfully reared at temperatures ranging from 

 15 to 30 C. (59 to 86° F.). However, it has been found that larvae, 

 particularly of the second and third instars can be kept at temperatures 

 as low as io° C. (50° F.) for months without injury. When these 

 larvae are later placed at high temperatures, development occurs nor- 

 mally. Since io° C. (50° F.) is too low for development, it is possible, 

 in this way, to keep larvae in any desired stage of development until 

 needed for experimentation. 



Since the pupal stage is non-feeding, the essential requirements for its 

 development are proper moisture and temperature. Pupae can be 

 successfully carried through to the adult stage in a medium of moist 

 sterile soil or plant mold. Adults of the Japanese beetle have been 



