IOWA ACADEMY OF SCIENCES. 187 



sheath downward with a peculiar sawing motion alternating 

 with a slight pause for the deposition of an egg. 



The eggs are one and one-half millimeters by one-third mil- 

 limeter, cylindrical, gradually tapering from a point near the 

 head back to an obtusely rounded tip; the anterior end is cut 

 off obliquely from one side and rounded from the other, coming 

 to an obtuse point. They are deposited in a continuous row, 

 from thirty to fifty, side by side, curving slightly around the 

 stem with their heads toward the edge of the sheath, from which 

 they are distant about one-third the circumference. The time 

 occupied in actual deposition is from twenty to forty minutes, 

 but the selection of a location and the catching of the sheath 

 edge often occupies several hours. 



Although the eggs were deposited through a period of two 

 weeks or more they apparently all hatched at about the same 

 time; the time evidently depending considerably upon favorable 

 conditions of temperature and moisture, for, up to July 2d, no 

 larvse had been observed either in the cages or in the field. On 

 this afternoon the air was very oppressive, and remained so 

 until cleared by a heavy thunder storm durirg the following 

 night. On the morning of the 3rd they were observed just 

 emerging from the eggs in the cage, and examinations showed 

 that they had hatched in the field also. The earliest depo- 

 sition from which they were observed to issue on this date was 

 made May 28th, and the latest on June 9th, while the majority 

 were deposited June 4:th and 5th. This gives from twenty- six 

 to thirty- eight days, with an average of about one month, as 

 the period of incubation. 



The freshly hatched larvas have shorter and blunter heads 

 than the adults, and are much more active, but within a week 

 or two the head has elongated, and it has adopted the sluggish 

 habit of the adult. 



Upon hatching, the larvc© immediately arrange themselves 

 along the base and margins of the broad leaves parallel to the 

 veins, where they remain stationary for weeks at a time, so 

 closely resembling the rust spots and discolorations occasioned 

 by their punctures that ihe chance of their detection is slight, 

 or, they ascend to the head, where they conceal themselves so 

 effectually among the glumes and sheaths upon which they 

 feed, that one might carefully examine a head and pronounce 

 it free from them, only to find, on shaking it violently, that it 

 contained a whole colony. Here they stay until the head ripens 

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