HABITS OF THE LARVA OF BELLURA MELANOPYGA. 1 05 



in the same locality, frequently intermingling and contiguous. 

 In the region studied Castalia odorata is surprisingly exempt from 

 insect attacks. Beutenmiiller ('02, p. 440) states that, in the 

 vicinity of New York City, the caterpillar of Bellura melanopyga 

 "bores in the leaf-stalks of the common white pond lily and 

 yellow pond lily." Assuming that the "common white pond 

 lily" referred to above is Castalia odorata, it appears that the 

 larva may work normally on it in certain other localities. How- 

 ever, the evidence collected in the Douglas Lake region is entirely 

 contradictory. 



Experiments were carried on at the laboratory with the view 

 of determining whether or not these larvae could be forced to 

 use other food. The following are typical experiments and 

 results: Experiment I. Two larvae, each 6 mm. in length, were 

 transferred to a watch glass containing a piece of leaf of the 

 white waterlily (Castalia odorata} which was kept moist. During 

 the first eighteen hours the larvae wandered restlessly about, 

 then finally began working on the white waterlily leaf and at the 

 end of four hours one had completely buried itself and the other 

 was making similar headway. Fresh pieces of the white waterlily 

 leaf were used to replace the eaten ones from time to time and 

 these larvae were kept thus for twelve days. At the end of that 

 time both were alive, apparently in healthy condition and one 

 ecdysis had occurred. The results show that it is possible for 

 the larvae to use the white waterlily as food when forced to do so 

 by the absence of the normal food. Experiment 2. Both yellow 

 and white waterlilies were placed in the same aquarium which was 

 stocked with several larvae, 4 cm. in length. The larvae attacked 

 the yellow waterlilies and worked on them continuously. Ul- 

 timately the food plants were consumed and a famine was allowed 

 to occur. After a lapse of several hours only one case was ob- 

 served where larvae were attempting to tunnel into the petiole 

 of one of the white waterlilies and it was finally abandoned, the 

 larvae wandering restlessly about the aquarium. Experiment j. 

 Larvae were placed in covered dishes containing Potamogeton 

 natans and Sagittaria sp., plants which occurred in abundance in 

 the same habitat with the waterlilies, and were left thus for 

 several days. The tissues of these plants were invariably and 

 constantly refused. 



