198 



NATURAL HISTORY OF ARTHROPODS. 



FlG,276. — Egg laying of Rocky Mountain locust; aaa, female 

 in different positions, ovipositing; 6, egg-po<l extracted 

 from ground, with the end broken open; c, a few eggs 

 lying loose on the ground; d e, show the earth partially 

 removed, to illustrate an egg-mass already in place, and 

 one being placed; /, shows where such a mass has Deen 

 covered up. 



buried. The abdomen stretches to its utmost for this purpose, especially at the 

 middle, and the hole is generally a little curved, and always more or less obUque. 

 Now, with hind-legs hoisted straight above the back, and the shanks hugging more or 



less closely the thighs, she commences 

 ovipositing, the eggs being voided in 

 a jjale glistening and glutinous fluid 

 which holds them together and binds 

 them into a long cylindrical pod, cov- 

 ered with particles of earth which ad- 

 here to it. When fresh, the whole 

 mass is soft and moist, but it soon 

 acquires a firmer consistency. It is 

 often as long as the abdomen, and 

 usually lies in a curved or slanting 

 position. It is never placed much 

 more than an inch below the surface, 

 except where some vegetable root has 

 been followed down and devoured, 

 and the insect leaves her eggs before 

 emerging; in this way the mass is 

 sometimes placed a foot below the 

 surface. The eggs which compose this mass are laid side by side to the number of 

 from thirty to one hundred, according to the size of the mass. They are 0.15 to 0.20 

 inch long, one-fourth as wide, slightly curved, of a pale yellow color, and rather larger 

 at the anterior than the posterior end. As the hatching period approaches they 

 become more plump and pale, and the embryo, with its dark eyes, is visible through 

 the shell, which is now somewhat transparent. The opening to this egg-mass is cov- 

 ered up by the mother, but the newly hatched insect has no difliculty in escaping. 



"The young locusts display gregarious instincts from the start, and congregate in 

 immense numbers in warm and sunny places. They thus often blacken the sides of 

 houses or the sides of hills. They remain thus huddled together during cold, damp 

 weather. When not travelling, and when food is abundant, or duiing bad, rainy 

 weather, they are fond of congregating on fences, buildings, trees, or anything removed 

 from the moist ground. They also prefer to get into such positions to undergo their 

 different moults. In fields they collect at night or during cold, damp weather, under 

 any rubbish that may be at hand, and may be enticed under straw, hay, etc., scattered 

 on the ground. Old prairie-grass affords good shelter, and where a wheat-field is sur- 

 rounded with unburned prairie, they will gather for shelter along the bordere of 

 this last. 



" The young locusts soon after hatching begin to display their migratory nature ; 

 but so far we have been unable to ascertain that they travel in stated directions as 

 some persons have asserted. Our experience has been that different clusters of them 

 have been noticed to travel in all directions at the same time. 



"It is when they are abundant and vigorous enough to bare the gi'ound of vegeta- 

 tion, and this principally after they are half-grown, that the habit of migrating in large 

 bodies is developed. In 1877 scarcely any disposition to migrate was shown, and this 

 was in strong contrast with what occurred in 1875. In a year like this last, when they 

 are vigorous and abundant, their power for injury increases with their gi-owth. At 



