|[Note Guidelines] Photographer's Note|
|About the Two-striped Grasshopper|
Two-striped grasshopper, Melanoplus bivitattus. Adults are 1 to 2 1/4 inches long. Two light colored stripes extend from eyes to wing tips. They are primarily weed feeders, but will readily move into cultivated crops.
These insects cause some damage every year, but become very destructive during outbreak periods. An often asked question during outbreak years is: Why are there so many? Weather is the main factor affecting grasshopper populations. Outbreaks are usually preceded by several years of hot, dry summers and warm autumns. Dry weather increases nymph and adult survival. Warm autumns allow grasshoppers more time to feed and lay eggs. Cool, wet weather slows nymphal development, reduces the number of eggs laid, and increases the incidence of diseases. Grasshoppers have a high reproductive capacity. The female can lay an average of 200 eggs during a single season. Under favorable conditions up to 400 eggs can be laid. Approximately 40 eggs can be laid even if unfavorable conditions exist. Thus, 10 times more eggs can be produced during favorable conditions. With an average of 200 eggs per female, 198 eggs or young grasshoppers would have to die if the population were to remain the same. If, instead of only two adults surviving, there are four, six, eight, 10 or 50, then the adult population the following year will be increased two, three, four, five or 25 times, respectively.
Grasshopper eggs are laid 1/2 to 2 inches beneath the soil surface in pod-like structures. Each egg pod consists of 20 to 120 elongated eggs securely cemented together; the whole mass is somewhat egg-shaped and covered with soil. The egg pods are very resistant to moisture and cold and are affected very little by winter conditions if the soil is not disturbed. Eggs are deposited in a variety of non-crop areas including ditches, fencerows, shelter-belts and weedy areas. They are also laid in cropped areas including late season crops, weedy fields, hay fields and alfalfa. Grasshopper egg hatch normally begins in late April to early May. Peak hatch occurs about mid-June and is usually near completion by late June. Cool and extremely dry springs may delay hatch, allowing it to continue into July.
Young grasshoppers are referred to as nymphs. They are similar to adults in general appearance, but are smaller and have wing pads instead of wings. There are usually five or six nymphal stages and the length of time from egg to adult is 40 to 60 days.
Adults of crop-damaging grasshopper species become numerous in mid-July with egg laying usually beginning in late July and continuing into the fall. In general, only one generation of grasshoppers is produced per year.
Alex99, mayuresh has marked this note useful
Only registered TrekNature members may rate photo notes.