74 CEREAL AND FORAGE INSECTS. 



weed or grass stem, then gradually grow restless, get in motion again, 

 and resume the line of march. 



At rare intervals they pause long enough to eat a few mouthfuls 

 of grass, but one may often watch these parades for hours and not 

 see one of the young travelers stop for a single bite. Not infre- 

 quently larvae of different ages will join the same procession. More 

 or less silk is spun in the track of the moving line at times and this 

 tenuous silken trail may aid in maintaining the continuity of the 

 procession. If by any chance, as sometimes happens, half a dozen 

 or more become separated from their companions, they eagerly join 

 any procession they can find in their neighborhood. Indeed, during 

 the first month of larval life the young are exceedingly gregarious 

 and generally refuse food when placed alone. 



On July 30, 1909, a single very much belated newly hatched larva 

 was found on Bouteloua, and an effort was made to rear it. But, 

 although furnished with ample food, its meals were brief and it was 

 forever on the move, looking for company. It died August 9, "in 

 the midst of plenty," apparently normal and health}', butf unable to 

 find the companionship for which it had searched for ten long days. 



During the nights, which are almost always very cool at this alti- 

 tude, the young gather in a ball on some convenient stem and remain 

 in masses, but are uneasy until the warmth of the morning starts 

 them off for another day's "tramp." 



HABITS OF THE OLDER LARV.E. 



The more mature larvae are wasteful eaters, biting off and dropping 

 many grass blades that they do not use. In the dry weather that 

 prevails on many parts of the range, the blades of the Bouteloua and 

 other food grasses are roiled up automatically into a tight cylinder 

 to prevent too much evaporation. The larvae usually bite off and 

 drop the pointed tip, beginning to eat an inch or so below the apex 

 of the blade, taking everything to the root. The grass is swallowed 

 in rather coarse fragments and when voided is but little changed by 

 digestion, much of the chlorophyl still remaining in the cells. 



The jaws are powerful, for their food is leathery and nearly juice- 

 less, requiring a strong bite. Several times while in captivity the 

 larvae have eaten quite a piece of heavy linen paper, their mandi- 

 bles snipping through the firm edge of the sheet with an audible 

 click. 



As a rule the larvae, especially in the earlier instars, are shy feeders, 

 and the presence of a person in their vicinity is generally a signal to 

 suspend all operations for the time being and to remain perfectly 

 motionless. They sometimes display their annoyance at the in- 

 truder by a curious series of body motions, throwing themselves 



