74 
mens reared at high temperatures are brilliant, the cephalic wings 
possessing a pleasing blue-gray hue. Likewise females reared at 
high incubator temperatures are highly colored and deviate to a large 
extent from the type specimen in the field. Abdomen dark grayish 
fuscous above, white beneath: caudal margin of segments on the 
dorsum with a fine line of white scales. Frenulum consisting of one 
long stout spine. 
Genitalia strongly chitinized; anellus with two dorsal projecting 
lobes supported by two chitinous arms; face of clasper oval and 
spinose ; tegumen trifurcate ; sacculus of the harpe bearing one large 
and two smaller stout spines. 
FEMALE 
Alar expanse 25 to 34 millimeters. 
Cephalic wing of the female dull yellow or sometimes sulphurous, 
the costa and inner two-thirds of the wing more or less streaked with 
brown ; a serrate brown line is present on the outer third of the wing 
and extending its width, followed on the outside by a narrow yellow 
band more or less serrate on its outer margin. On the outside of the 
latter there is present a brown band interspersed with yellow. Caudal 
wing grayish brown with a rather broad light ochreous fascia begin- 
ning slightly caudacl of the costa and terminating short of the caudal 
margin of the wing. In some specimens cephalic wings may be dull 
Fig. 38. — Adults of the European corn borer : At left, male moth ; at right, female moth. 
Not quite twice natural size 
yellow and cinnamon brown tinged with ferruginous, and with the 
caudal wings very pale brown streaked irregularly with shades of 
darker color. Frenulum of the female consisting of two long spines 
and a shorter, more slender one. 
Ovipositor terminating in a chitinous plate emargined with long 
and snorter amber-colored setae; genital opening without strongly 
chitinized cephalic margin; chitinized plate caudad of the genital 
opening well developed. 
SEASONAL HISTORY 
The seasonal history of the corn borer in various localities is va- 
riable, as would naturally be expected of any widely dispersed insect ; 
but a somewhat surprising feature is that in localities where the 
climatic complex is superficially the same, there is a variation in 
the number of generations annually. Between the areas of infesta- 
tion in eastern Massachusetts and western Xew York, the early 
spring mean temperatures, the frost dates in spring and fall, and 
the length of the growing season are comparable. If there is any 
apparent difference in the two localities it is slightly cooler in 
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