138 PHYSICAL GEOGRAPHY. 



and occur at long intervals over limited areas. It has been no un- 

 common thing, however, for them to be so abundant as to entirely 

 cover the ground. 



Egg Laying. — The time for the commencement of egg laying 

 varies somewhat in different years and localities. Generally it 

 commences about the middle of August and continues to severe 

 frost, and lasts therefore from six to eight weeks. In 1S76 the 

 locusts were laying eggs far into October. The female generally 

 lays three times, at intervals of from three days to three weeks. 

 Each egg mass contains from twenty to thirty-five eggs. 



Place and Method of Egg Laying — The places for egg laying are 

 not uniformly the same. They seem to prefer ground that is high 

 and dry, and somewhat compact. Low lands, however, that are 

 dry are much used for this purpose. Road sides are frequently 

 honeycombed with holes, but comparatively few egg masses are 

 found there. New breaking is generally fuller of eggs than any 

 other kind of ground. The number laid is often simply enormous. 

 I have often found sections of land where the eggs averaged from 

 ten to fourteen thousand, and in rare instances to upwards of twenty- 

 one thousand to the square foot. These enormous numbers are only 

 reached during years when the locust swarms are exceptionally 

 dense. 



Manner of Egg Laying. — When the female is about to lay her 

 eggs she selects a spot and " forces a hole in the ground by means 

 of the two pairs of horny valves, which open and shut, at the tip 

 of her abdomen, and which from their peculiar structure are ad- 

 mirably fitted for the purpose. With the valves closed she pushes 

 the tips into the ground, and by a series of muscular efforts, and 

 the continued opening and shutting of the valves, she drills a hole 

 until in a few moments (the time varying with the nature of the 

 soil) the whole abdomen is buried. The abdomen stretches to its 

 utmost for this purpose, especially at the middle, and the hole is 

 generally a little curved and more or less oblique. Now with hind 

 legs hoisted straight above the back and the shanks hugging more 

 or less closely the thighs she commences ovipositing." (Riley.) 

 Before the eggs come out there exudes from the end of the body 

 a mucous matter which fills the bottom of the hole and bathes the 

 valves. The eggs separately, by convulsive throbs, are placed in 

 order in the hole. The mucous matter binds all the eggs together. 

 When the locust is through with this process, she fills the upper 



