648 AN INTRODUCTION TO ENTOMOLOGY 



The pickle-worm, Diaphdnia nitiddlis. — This species is closely 

 allied to the preceding one. The wings of the moth are yellowish 

 brown with a purplish metallic reflection; a large irregular spot on 

 the front wings and the basal two-thirds of the hind wings are semi- 

 transparent 3'ellow. The tip of the abdomen is ornamented with a 

 brush of long scales, as in the preceding species. The range and 

 habits of this species are quite similar to those of the melon-worm; 

 and it should be fought in the same way. 



The Webwornis. — The larvas of many pyralids have the habit of 

 spinning a silken web beneath which they retreat when not feeding, 

 and on this account have been termed webworms. Several species 

 of these webworms belong to this family; among them are the follow- 

 ing. 



The cabbage webworm, Hellula undalis. — This species infests 

 various cruciferas in the Gulf and South Atlantic States. The larva 

 is about 12 mm. in length, of a grayish yellow color, striped with five 

 brownish-purple bands. 



The garden webworm, Loxostege simildlis. — This species is most 

 injurious in the Southern States and in the Mississippi Valley. It 

 infests various garden crops and com and cotton. The larva varies 

 in color from pale and greenish yellow to dark yellow and is marked 

 with numerous black tubercles. 



The European corn-borer, Pyrausta nubildlis. — This is a greatly 

 feared pest which has recently appeared in this country. It is a 

 borer in the stems of plants, in which it winters as a partly grown larva. 

 Its favorite food appears to be com and especially sweet corn ; but it 

 infests other cultivated plants, as dahlias and gladiolus, and many 

 large-stemmed weeds. The full-grown larva measures about 20 mm. 

 in length; the adult moth has a wing-expanse of from 25 to 30 mm. 

 As this is written, efforts are being made by the National Government 

 and by several State Governments to prevent the spread of this pest; 

 and many circulars and bulletins are being published regarding it. 



Subfamily NYMPHULIN^ 

 The Aquatic Pyralids 



This subfamily is of especial interest as the larvae are nearly all 

 aquatic, differing in this respect from nearly all other Lepidoptera. 

 The larvae of most of the species live upon plants, like water lilies 

 and pond weeds, that are not wholly submerged; but in some species 

 the larva has a true aquatic respiration, being furnished with tracheal 

 gills. In our best known species, these tracheal gills are numerous 

 and form a fringe on each side of the body of long slender filaments, 

 which are simple in some species and branched in others. 



The larvas vary greatly in habits ; some species live free upon the 

 plants they infest; in some species, each lar\^a makes a case of two 

 leaf fragments fastened together at the edges; most of the described 

 larvce live in quiet waters, lakes, ponds, or pools, but the larva of 



