1919] Welch: Pyrausta Penitalis 217 



of locomotion, nutrition, protection, and respiration not by 

 structural developments, but by modified activities remarkably 

 similar to those of P. penitalis. 



FEEDING HABITS. 



Food Plants. — In the Sandusky Bay region, P. penitalis 

 was found only on Neliimbo lutea. Other plants in the same 

 habitats and on nearby shores were examined from time to 

 time, but appeared to be unaffected by this insect. However, 

 it is evidently a general feeder, since other writers have reported 

 it on Polygonum incarnatnm, Polygonum hydro pi per oides, Eupa- 

 toritim (species not given), and Nelumbo nucifera (''Egyptian 

 lotus"). An erroneous record of Apocynum cannibinum was 

 mentioned on a foregoing page. 



Leaf -feeding Period. — Two' well-defined periods can be 

 recognized in the feeding activities of the larvae, (1) an early 

 one, the leaf-feeding period, and (2) a later period, the petiole 

 period. These two periods were given bare mention by Smith 

 (1890a) and Hart (1896, pp. 180-181), but the details and 

 adaptations have not been described. 



After hatching, the young larvae feed upon the outer surface 

 of the Nelumbo leaf, removing the upper epidermis and a con- 

 siderable part of the underlying chlorophyll-bearing tissue. 

 The feeding areas are irregular and vary in size, depending upon 

 the amount of feeding done. They often become confluent, 

 forming large irregular areas. When first made, they are light 

 greenish, but soon change to brown and in time the whole 

 leaf, if heavily infested, assumes that color. 



While any part of the upper leaf surface is subject to attack, 

 feeding at the periphery differs, in certain distinct respects, from 

 that within the periphery, and likewise involves distinct 

 differences in accompanying adaptations. These activities will 

 be described in the reverse order of mention. 



Leaves bearing young larvae almost invariably show, when 

 examined critically, numerous, very fine strands of silk all over 

 the upper surface, marking the routes of the wandering larvae. 

 This apparent wastefulness in silk production is perhaps the 

 first form of aquatic adaptation to appear in the life-cycle since 

 the silken thread continually anchors the tiny larva to the leaf 

 during its search for an appropriate feeding place and aids in 

 preventing it being washed off the leaf by waves or other surface 



