22 



THE SUGAR-BEET WIREWORM. 



but it soon gave proraiso of beino; a sinipl(> and safe receptacle in 

 which to rear wire worms. 



The other style of cage was the common root cage (PI. VIII, fig. 2), 

 so often used for the study of underground insects. The cages used 

 in these experiments had the glass walls very close together (one- 

 eighth to one-fourth inch) so that there would not be much soil in 

 which the larv?e could hide. The root cages were not so successful 

 as it was hoped they would be, for the larvae were usually able to 



conceal themselves and 

 it seemed almost im- 

 possible to wet the 

 cages properly. Used 

 in conjunction with the 

 other cages, however, 

 they gave fair success. 

 The majorit}^ of the 

 young wneworms were 

 kept m large flower- 

 pots, so that in case of 

 accidents to the rearing 

 cages not all the larvae 

 would be lost. These 

 pots had an added ad- 

 vantage in that they provided soil conditions quite similar to those 

 out of doors. The flowerpots were emptied and examined from time 

 to time so that the larviP could be w^atched. 



Fig. 5. — Jauet ants'-ncst plasler-of-Paris cage, used in rearing 

 sugar-boot wireworms. A, compartment for larv*; B. com- 

 partment for water. (Original.) 



HABITS OF THE YOUNCr WIREWORMS. 



■ The young wireworms are quite active, moving over smooth sur- 

 faces or burying themselves in the loose soil with ease. Some placed 

 in a root cage buried themselves almost at once, but were tempora- 

 rily checked by a layer of compact earth about an mch below the 

 surface. On the following day several had entered the compact 

 layer and the next day one was noted at a depth of 4 inches. 



'\Mien very young they are unable to survive m dry earth even for 

 a relatively short time. Some which were placed in a petri dish 

 with dry soil w^ere dead at the end of five hours, a few dymg after the 

 first hour and a half. 



These larvae shun the light and when exposed to it hide under any 

 object which they can find. When placed in the petri-dish cages 

 they soon crawl between the layers of filter paper at the bottom. 

 Experiments were made to test their ability to locate food, by placing 

 a slice of sugar b(>et in the cages and noting the time it took them to 

 collect under it. The beet shce was not larger than a dollar and was 



