"But some of them had laid eggs in the ground in little cornucopia-like packets before dying or flying away. And much alarm was caused by predictions that millions of new hoppers would come out of the ground in the coming spring and eat all the crops while young, even if the old ones or more like them didn't come again in the summer and eat the mature crops. But these predictions were only partly fulfilled. Not many hatched out in the spring, and those that did seemed to be more anxious to get back to the Rocky Mountains where their brethren were than to eat the Kansas crops. Indeed as soon as the young hoppers got their wings--and that takes several weeks after they come from the egg--they began flying northwest. "So this remarkable and terrible invasion was over. And all the poor farmers, and the bankrupt or about to be bankrupt storekeepers and bankers and the idle lawyers and doctors and the terrified capitalists and the hard-studying entomologists drew a long breath of relief together." "But have the hoppers come back any time since 1876?" asks Mary. "No, that was the last invasion. There had been earlier ones, though, one or two of them just as bad as the Centennial-year one. Indeed Kansas was called the Grasshopper State on account of these terrible summer invasions. There was a bad one in 1866 and another in 1874. The invasions of 1874 and 1876 cost the farmers of the Mississippi Valley at least fifty millions of dollars in crops eaten up." "But what made them come to Kansas? Why didn't they stay in the Rocky Mountains? It's much more beautiful and interesting there than in Kansas, isn't it?" "Much, Mary. But it probably wasn't a matter of scenery with these tourist hoppers. Much more likely a matter of food. In those days there were no farmers with irrigated fields on the great plateaus along the eastern base of the Rocky Mountains in Colorado and Wyoming. Nothing much but sage-brush and not overmuch of that grew there. And probably there simply wasn't enough food for all the hoppers. So in seasons when there were too many hoppers or too little food--and if there was one, there was also the other--they flew up into the air, spread their broad wings and sailed away on the winds from the northwest for a thousand miles to Nebraska and Kansas and Texas. And that made an invasion." "But, then, why didn't they stay there, where there were corn-fields and wheatfields and vegetables?" persisted Mary.