446 journal of economic entomology [vol. 12 



Control 



Many of the last stage nymphs of the second brood were preyed upon 

 by the immature stages of several spiders which spun webs over the 

 leaves. The adults which survive the winter are comparatively few 

 so that the first brood does little injury. In case the second brood 

 nymphs should become too numerous on ornamental plantings they 

 may be controlled by using one of the nicotine sprays commonly used 

 against leaf bugs on apple. The sprays must be directed upward to 

 cover the undersides of the leaves. 



THE FUNCTION OF THE ANAL COMB OF CERTAIN 

 LEPIDOPTEROUS LARViE 



By S. W. Frost, State College Research Laboratory, Arendtsville, Pa. 



Lepidopterous workers are aware that certain larvae possess a comb- 

 like structure on the ventral aspect of the last abdominal segment. 

 Heretofore this comb has served simply as a convenient systematic 

 character for separating closely allied larvae such as Laspeyresia molesta 

 Busck and Laspeyresia prunivora Walsh from Laspeyresia pomonella 

 Clem. The writer has discovered a more interesting and, from the 

 standpoint of the larva, a more useful function of the anal comb. 

 While examining a larva of Sparganothis indocusalis Walk., a pellet of 

 frass was tossed with considerable force against the wall of the con- 

 tainer in which the larva was kept. Upon further examination the 

 use of the anal comb was revealed. The frass flows out from the 

 posterior end of the alimentary canal in a small pellet. The anal comb 

 is then bent downward until it touches the fras.^ and with a sudden snap 

 backwards it tosses the pellet away from the body. 



This interesting performance led to the examination of several other 

 larvae, both with and without the anal comb, with the idea of deter- 

 mining if any correlation exists between the habits of the larva and the 

 possession of the anal comb. Fourteen larvae were available for the 

 examination, all feeders of apple and representing various larval habits 

 as: Case bearers, leaf miners, borers, and external feeders. 



The case bearers, leaf miners and borers possess no anal comb and an 

 examination of their habits explains the uselessness of such a structure. 

 For example, Mineola indiginella Zellar and Tmetocera ocellana Schiff., 

 construct trumpet-hke cases from which they feed. The frass is re- 

 moved from the interior of their cases by means of their mandibles 

 and placed on the exterior of their cases. A comb would be of no 



