FACTOES DETEEMINING THE REACTIONS OF THE 

 LAEVA OF TEISTEBRIO MOLITOR. 



BY 



MAX MORSE. 



With Two Figures. 



The coleopteran genus Tenebrio is represented in America by sev- 

 eral species, but a. few of the commonest and best-known members are 

 introduced species, which have been imported from Germany. I refer 

 to Tenebrio molitor and obscura. The adults of these two forms may 

 be readily distinguished by differences in texture of the elytra, but 

 the larvae are distinguishable except to the trained entomologist wbo 

 is familiar with the various species. The species molitor is the 

 better known, although obscura is found associated with it very 

 frequently. Both species may be obtained, throughout the year, from 

 natural history and aquarist shops in the larger cities, where they are 

 used as food for birds, lizards, and the like. 



The reactions of these larvae to light have been studied by Loeb 

 ('91), by Radl ('03) and by Cole ('07). Loeb found them to be 

 decidedly negatively phototactic, and he also described marked stereo- 

 tropism (as Radl did later) which overpowers even the strongly 

 negative reaction to light. Cole made a detailed study of the reaction 

 of the larvae to luminous areas of different sizes. 



The following observations concern the method of response of the 

 animals to light and gravity. 



Before entering into the discussion of the reactions, a word may 

 be said concerning the organs for the reception of light. These lie on 

 either side of the head, immediately posterior to the base of the 

 antennae, upon the elevation bounding the antennal sulcus posteriorly. 

 They may be recognized by the brownish pigment which may be seen 



The Journal op Compaeative Necrology and Psychology. — Vol. XIX, No. 6. 



