154 ENTOMOLOGICAL NEWS. [April, '15 



Duration of Pupal and Adult Stages of the Meal 



Worm t Tenebrio obscurus Linn. (Coleop.). 



By PHIL RAU, St. Louis, Missouri. 



About September 15, 1913, a lot of the yellow meal-worm 

 larvae, Tenebrio molitor Linn., were found in a chicken- 

 house in eastern Kansas. They were under a board among 

 dry hen excrement and a multitude of their own shed 

 skins. On May 10 and 15 two of them transformed into 

 pupae. As no others pupated, I concluded the rubbish in 

 which they were kept was too dry, so I moistened it slightly. 

 This caused a growth of fungus which killed all the larvae. 



In October of the same year I found in my own pigeon- 

 house in St. Louis a lot of larvae of the dark meal-worm, 

 Tenebrio obscurus, and made notes on the longevity of the 

 adults and the length of time each spent in the pupal stage. 



It is interesting to note that while the two lots were side by 

 side in the laboratory, heated during the day in the winter, the 

 dark meal-worms commenced to pupate at the end of Febru- 

 ary and the yellow ones, excepting the two mentioned hereto- 

 fore, showed no signs of pupating up to the time of their 

 death in June.* 



At the end of May a search in the pigeon-house revealed a 

 number of larvae and adults, commingled with shed skins 

 and some dead adults. Several of the larvae were taken for 

 controls. Here we have larvae which spent all of their lives 

 in the open, in contrast with those fed in the laboratory. 

 Eleven of these pupated in June and are added to the table, 

 denoted by "s." 



Table I gives the data of the duration of the pupal and 

 adult life and the total for the dark meal-worm, T. obscurus. 



It is interesting to note that all of these controls ("s" in 

 table i), lived shorter periods as adults and spent shorter 

 periods as pupae. However, I do not consider that this 

 necessarily indicates that the outdoor conditions of existence 



*That these beetle adults appear considerably earlier than do the 

 yellow ones confirms the observation of F. H. Chittenden in Bull. U. S. 

 Dept. Agr. Div. Ent. N. S. No. 4, rev. ed., p. 118. 



