00 THK ENTOMOLOOIST's RECORD. 



to have permanent breeding-places, from which it flies out in some 

 seasons and swarms over the cultivated districts south and east. This 

 is the true migratory locust of North America, and probably causes 

 more real injury than all the other species put together. So marked 

 is the migratory instinct in this species that swarms, hatching in the 

 basin of the Saskatchewan, have been traced to the Gulf of Mexico in 

 the course of one season. 



In 1878 the United States Entomological Commission pubhshed a 

 Ilcjaiit extending to 177 pp. (to which were added appendices extending 

 to 279 pp.) on the migrations of, damage caused by, and the best methods 

 of preventing the injuries, &c., caused by, this species. According to 

 this Ucport the flights taken by locusts in North America may extend 

 from one to two thousand miles, i.e., from their native breeding-places 

 in Montana, to Kansas, Missouri, and Texas. As a rule, the flight is 

 only undertaken during a part of the day and in clear, fair weather, so 

 that the want of food, cloudy or rainy weather, and adverse winds may 

 prevent them from rising and taking wing. The rate at which they 

 fly is variously estimated from 3-15 miles an hour — determined by 

 the velocity of the wind — and it is stated that insects which leave 

 Montana in July may not reach Missouri iintil late August or early 

 September. The llrjiort speaks of these as " invading swarms," since 

 they leave the permanent area of distribution to travel south or south- 

 east. It also mentions " return swarms," which, having hatched in 

 the invaded districts, become adult there and then move northward or 

 north-westward in April and ]\Iay. It should be noticed that the 

 southern flight takes place in July, as in Algeria, and the northern 

 flight in the spring. 



The height at which migrating swarms move is probably very 

 variable and certainly difficult to estimate, the want of definition and 

 compactness about a moving swarm making the calculation practically 

 impossible. Locusts were observed at Bismarck above the cumulus 

 clouds. The upper portions of passing swarms have been brought into 

 view by a field-glass when invisible to the naked eye. Byers states 

 that in 1868, in August, he saw a flight when in the Snowy Eange, 

 reaching apparently to the highest limit of vision when on the highest 

 peaks, Avhilst Putnam on Parry's Peak (18,383ft.) states that in 1872 

 a swarm could be seen filling the air like snowflakes to a great height 

 above the extreme summit of the peak. There is evidence, therefore, 

 that locusts can fly at a height of 13,000ft. -15,000ft. That Mind has 

 considerable eftect on the direction of flight was well shown by obser- 

 vations on two swarms, an upper and lower, going in ditierent direc- 

 tions at the same time. It has also been observed that a sudden change 

 of wind will often bring a flying swarm to the ground, whilst a sudden 

 lowering of the temperature will most certainly do so. "With regard 

 to this, Byers says that " towards noon, on bright, warm days, the 

 locusts rise by circular flights, each seeming to act individually, to a 

 considerable height, and then all sail away with tolerable regularity in 

 one general direction. If there be no wind many of them continue 

 whirling about in the air like bees swarming, but away beyond myriads 

 can be seen moving across the sun towards the south-west, looking 

 like snowflakes. If there be a change in the atmospheric coixlitions, 

 such as the approach of a thunderstorm or gale of wind, they come 

 down precipitately, seeming to fold their wings and fall by the force 



