366 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 5 



Bragg was sent to investigate the trouble and D. virgijera was found 

 to be doing the damage. Mr. Bragg spent considerable time hunting 

 for the injuries of the beetle during 1910 about Fort Collins and was 

 able to report it fairly common on ground where corn had been grown 

 for two or more years in succession and, in a few instances, the injuries 

 were very severe. During 1911, the injuries seemed to be less, though 

 the insect has been taken frequently about Fort Collins upon corn 

 during the late part of the summer. 



This insect occurs in two forms, one striped and closely resembling 

 D. vittata as shown in Figure 5; the other with the wing covers black 

 except for the narrow yellow margins and yellow tips, as shown in 

 Figure 4. Specimens were sent to Professor Wickham, of the Iowa 

 State University, who determined the striped form as D. virgijera 

 Lee. and the dark form as filicornis Horn, and stated that virgijera 

 is known from New Mexico, Arizona, and Sonora, while filicornis 

 is known from New Mexico. I have not been able to find any refer- 

 ences to either of these insects from other localities and the species 

 w^as not represented in our collection here until taken in the patch 

 of sweet corn mentioned above. 



It did not seem possible to me that these two forms, with some 

 intergrading in the color markings, could represent two species, as 

 they occur in practically equal numbers together in all cases where 

 we have observed them. Furthermore, the striped form had every 

 appearance of being the female beetle J3,nd the black form, the male, 

 and the two forms have frequently been taken in copula. Late in the 

 summer, the striped form was found to be full of eggs, whereas ova 

 never developed in the dark form, so I think the conclusion is safely 

 drawn that D. filicornis Horn is the female of D. virgijera Lee. The 

 antennal differences as given in the original descriptions seem to be 

 constant for the two sexes. 



Mr. Bragg follow^ed the habits of this insect quite carefully in the 

 j&eld but was unable to find the eggs out of doors. Beetles brought 

 into the laboratory, however, deposited eggs quite freely in test tubes. 

 The eggs are pale yellow in color and measure about .65 mm. in length, 

 .45 mm. in width, and are finely reticulated on the surface. See 

 Figures 6 and 7. The larva is pale yellowish in color, 11 mm. in 

 length when fully grown, and has a conspicuous black anal plate. 

 See Figures 2 and 3. The length of the beetles varies little from 5 mm. 



It seems certain from the observations that we have already made 

 that the insect is single-brooded, and has practically the same life 

 history as D. longicornis. This being the case, the very simple remedy 

 will be, not to grow corn after corn Avhere this insect has been at all 

 common the preceding year. 



