While checking on the status of goldenrod bloom in a park in southwest Ohio yesterday, I kept finding myself surrounded by hordes of hop happy grasshoppers and katydids. Each step that I took launched hundreds. They had great entertainment value as they sprang forth ricocheting off me, nearby plants, and a passing jogger in a seemingly out-of-control effort to escape.
Grasshoppers and katydids belong to the insect order Orthoptera (ortho = straight; ptera = wing). Grasshoppers belong to the suborder Caelifera and most have relatively short antennae. Katydids belong to the suborder Ensifera and are sometimes called Long-horned Orthoptera for their long, thread-like antennae. Katydid females also sport a distinctive, long, blade-like ovipositor (ovi = egg; positor = deposit) jutting from their posterior.
The bounding orthopterans I experienced yesterday were dominated by two species: Differential Grasshoppers (Melanoplus differentialis) and Red-Legged Grasshoppers (M. femurrubrum). I also spotted some beautiful Black-Legged Meadow Katydids (Orchelimum nigripes) converting among the multitudes. The hopping hordes included late instar nymphs of all of these species.
Although high numbers of katydids occasionally occur, grasshoppers are notorious for being capable of producing dramatically high populations (= outbreaks). Climate plays a critical role in producing dramatic year-to-year fluctuations in grasshopper populations. Dry summer conditions support grasshopper egg survival which is one of the reasons grasshopper outbreaks are more common on the Great Plains compared to Ohio. Grasshoppers lay their eggs in the soil and long periods with wet soils can drown eggs or support fungal infections that will kill the eggs. Conversely, low soil moisture favors egg survival.
Nymphs and adults have chewing mouthparts and are capable of causing serious plant damage. However, late instar nymphs are particularly damaging because they eat more compared to the earlier instars or the adults. On the other hand, adult grasshoppers are more prone to move en masse to new locations. So, while immature grasshoppers produce more damage, adults are most responsible for damaging populations moving from agricultural areas into surrounding landscapes.
Late season grasshopper problems often arise when adjacent agricultural crops are harvested or grasslands mature causing grasshoppers to move to find new food sources. Defoliation is the primary injury to plants, but fruit and ripening kernels of grain will also serve as food. Indeed, grasshoppers will feed on just about anything as long as they do not detect a feeding deterrent. Reports from the Great Plains are common of grasshoppers eating paper, paint, window screen, window or caulking, fence posts, hoe handles, etc. during grasshopper outbreaks. Heavy infestations of grasshoppers may require chemical treatment to reduce or prevent serious damage to sensitive plants.