REPORT OF THE STATE ENTOMOLOGIST I918 



31 



Stage lasts about 8 days. About 59 days are required for the life 

 cycle of the second generation. The biological data given above is 

 based largely upon the work of Mr Caffrey and his associates at 

 the Arlington- (Mass.) Laboratory. 



Available data indicate a connection between the percentage of 

 stubble infested and the stalk infestation and, generally speaking, 

 if the stalk infestation is below 10 per cent or thereabouts, the 

 stubble infestation may be less than i per cent; while over 30 per 

 cent stalk infestation may result in nearly 14 per cent of the stub- 

 ble being infested, especially if the latter is long, while badly 

 infested fields having a stalk infestation of 70 per cent or more 

 may have nearly 60 per cent of the stubble inhabited by borers. 



Description. The female moth is pale yellow with a robust body 

 and a wing expanse of a little over an inch. The outer third of the 

 fore wing is marked by two darker serrate lines. The hind wings 

 are a plain yellow. The male is reddish brown and has a long, 

 slender body. It is slightly smaller and much darker than the female. 

 There is in this sex a pale yellow streak between the two serrate lines 

 on the fore wings and two small yellowish spots near the middle. 

 The hind wings are grayish with a broad band of pale yellow. 



The nearly full-grown, overwintering caterpillars are about 



three-fourths of an inch 

 in length, yellowish gray, 

 brown headed, the body 

 minutely brown spotted and 

 with indistinct longitudinal 

 reddish or dusky stripes. 

 They may be distinguished 

 from most other corn borers 

 by the series of well-de- 

 veloped, homy, light brown 

 tubercles, each with one or 

 more short, stout hairs. The 

 arrangement of the tubercles 

 on the posterior extremity 

 is shown in figure 2. These 

 are the only caterpillars 

 which feed upon the de- 

 veloping tassels, bore in all 

 portions of the stem and 

 cob and devoiir the com 

 characteristics of other com 



Fig. 2. Posterior extremity of a 

 corn borer from above, showing 

 tubercles, or warts, and hairs 



upon the 

 insects.) 



cob. (See page 61 for 



