RATE AT WHICH YOUNG LOCUSTS l^AVEL, 235 



armies of the young locusts wben on the march, and I>^)ngingk relates 

 having seen them swim over the Diijestr for a stretch of li Gorman 

 miles, and in layers 7 or 8 inches thick.^*^ We have had similar experi- 

 ence with our own species. In 1875, near Lane, Kans., they crossed the 

 Potawotomie Creek, which is about four rods wide, by millions j while 

 the Big and Little Blues, tributaries of the Missouri, near Independence, 

 the one about 100 feet wide at its mouth, and the other not so wide, 

 were crossed at numerous places by the moving armies, which would 

 march down to the water's edge and commence jumping in, one upon 

 another, till they would ponton the stream, so as to effect a crossing. 

 Two of these mighty armies also met, one moving east and the other 

 west, on the river-bluff*, in the same locality, and each turning their 

 course north and down the bluff', and coming to a perpendicular ledge 

 of rock 25 or 30 feet high, passed over in a sheet apparently 6 or 7 

 inches thick, and causing a roaring noise similar to a cataract of water. 

 (Riley's Eighth Report, p. 118.) 



The experience of correspondents as to the movements of the young 

 (App. 15) is very conflicting, as it naturally would be from what 

 we have already said. One man will notice the insects moving with 

 the wind, and conclude that it is the rule for them to do so j another, 

 against the wind, and draw an opposite conclusion. 



RATE AT WUICH THE YOUNa TRAVEL. 



" When about half-grown they seldom move at a greater rate than 

 three yards a minute, even when at their greatest speed over a tolera- 

 bly smooth and level road, and not halting to feed. They walk three- 

 fourths this distance and hop the rest. Two consecutive hops are sel- 

 dom t ikeu, and any individual one may be run down and fatigued by 

 obliging it to hop ten or twelve times without a rest." 



According to Sydow, the young of the European migratoria travel, 

 when at their most rapid gait, a German mile in four hours. Even tak- 

 ing the shortest German mile, or nearly four English miles, we very 

 much doubt the accuracy of this statement, for though the migratoria 

 is a larger species than spretus^ we cannot believe that it travels nearly 

 ten times as fast, and we have again and again timed our own species. 



THEY" REACH, IN THE TEMPORARY REGION, BUT A FEW MILES EAST 

 OP WHERE THEY HATCH. 



"At the rate at which they travel, as just described, they could not 

 extend many miles, even if they continued to travel in one direction 

 from the time of hatching until maturity. They travel, on an average, 

 not more than G hours per day ; and their unfledged existence termi- 

 nates in from G to 8, say 7 weeks. It is very easy to calculate from these 

 facts that if they continued in one direction from the time they hatch 

 until they acquire wings, they could not extend 30 miles. In reality, 



s^Koppen loc. cit, p. 43. 



