June, '19] MOSHER: EUROPEAN CORN AND OTHER BORERS 259 



prothorax nearly always has a chitinized shield on the dorsum which, 

 in most species, does not extend as far ventrad as the spiracle. This 

 area of the thorax properly has six setse on each side, two of these, one 

 cephalic (seta I) and one caudal (seta II) are usually quite near the 

 median line. The figures show the left side of the prothorax from the 

 median line of the dorsum to that of the venter. Beside these dorsal 

 setae is a group found nearly always between the spiracle and the 

 cephalic margin of the segment, but sometimes a little ventrad of the 

 spiracle. Farther ventrad is a group, usually of two setse, between 

 the spiracular group and the coxa. Near the coxae, usually between 

 them and the median line of the venter, is one, or possibly two setae, on 

 each side. 



The following families may be found in searching for corn borers: 



a Prolegs may be represented by swellings but hooks are never present; thoracic 



legs may or may not be present; setal arrangement never as in Fig. 11, no. 



13. Prodoxidce 



aa Prolegs, or at least crochets, nearly always present, if not, setal arrangement as 



in Fig. 11, no. 13. (See Gelechiidse.) 



b A group of three setiE in front of the thoracic spiracle. 



c Prolegs with one complete circle of large hooks and numerous irregular rows 



of very small ones (Fig. 11, no. 2) Acrolo phidoe 



cc Prolegs never with the small hooks as in Fig. 11, no. 2 and never with more 

 than three rows. 

 d Hooks of prolegs arranged in two bands, one on each side of the proleg 



(Fig. 11, no. 6) jEgeriidce 



dd Hooks of prolegs arranged in a complete circle (sometimes absent in 



Gelechiidse). 



e Of the four setae nearest the median line on the dorsum of the ninth 



abdominal segment, the caudal two (setae II) are closer together than on 



any other segment (Fig. 11, nos. 9, 10) ; body usually not tapering at the 



caudal end nor sharply constricted between segments Tortricidae 



ee The four setaj on the dorsum not varying greatly in arrangement on the 

 ninth abdominal segment; body usually tapering at the caudal 



end and often strongly constricted between segments 



CEcopfioridcB 



bb With two setse in front of, or occasionally shghtly below, the thoracic spiracle; 



one of the setse often very weak or small so that it is not easily located. 



c Hooks of prolegs arranged in a complete circle or one nearly complete (Fig. 



12, nos. If), 17, 25), never with a single row on the mesal margin. .Pi/ralidvE 



cc Hooks of prolegs in a single row or band along the mesal margin (Fig. 14, 



nos. 37. 42) Xocluidoe 



Prodoiida'. — The larvie of this family are found only in Yuccms ;in(l 

 are only likely to be confused with tlujse Gelechiidie which lack prolegs. 

 The setal and ocellar arrangement should be enough to distingui.'sh 

 them and no •rclcchiid borer has been described from Yucca. 



