Grasshopper
Grasshoppers eat large quantities of foliage both as adults and during their development, and can be serious pests of arid land and prairies. Pasture, grain, forage, vegetable and other crops can be affected. Grasshoppers often bask in the sun, and thrive in warm sunny conditions, so drought stimulates an increase in grasshopper populations. A single season of drought is not normally sufficient to stimulate a major population increase, but several successive dry seasons can do so, especially if the intervening winters are mild so that large numbers of nymphs survive. Although sunny weather stimulates growth, there needs to be an adequate food supply for the increasing grasshopper population. This means that although precipitation is needed to stimulate plant growth, prolonged periods of cloudy weather will slow nymphal development.
Differential grasshopper
An adult female lays up to 6 egg masses in soft soil, each of which can contain 40–200 eggs. The eggs begin embryonic development the summer they are laid, then enter diapause for the winter, to hatch over period of about two weeks in early summer of the next year. There is one generation per year. The nymphs take about 32 days from hatching to reach adulthood. Their development is well synchronized, and most nymphs transform to winged adults during a period of just a few days.
Differential grasshoppers are polyphagous, eating both grasses and forbs, but experiments have shown that they grow faster if fed forbs. The most favored food plants tend to be giant ragweed ("Ambrosia trifida"), common sunflower ("Helianthus annuus"), and prickly lettuce ("Lactuca serriola"). Adults can detect a chemical change in wilted lettuce and sunflowers and will tend to avoid these plants.