Bug of the Week
Greenstriped Grasshopper (Family Acrididae)
This BOTW rates a Vocabulary Alert.
Thanks to her own personal tinnitus, the BugLady enjoys cricket-like sounds from the fields even when they are covered with snow, but the sounds she heard a few days ago were the real deal. They’re back.
The spring of 2010 came early and stayed. On April 30, 2010 the BugLady photographed an adult grasshopper on her road. She sent the photo to a grasshopper expert (it takes a village to write a BOTW) with two questions: who is it, and how it had traveled from egg to adult so early in the year? It turned out to be a Greenstriped grasshopper (Chortophaga viridifasciata) (Latin scholars, have at it), in the colorful Family Acrididae. This year, 2011, Greenstriped grasshoppers (GsGs) started up on June 3.
If you’re east of the Rockies from April through the first half of summer, there’s a GsG near you. The farther east you go, the more common they are. In the eastern half of their range, they are partial to brome grass, the alien grass that takes over many old fields, but they eat other grasses, too, and the occasional forb. When it feeds on a blade of grass, a GsG severs a portion of a leaf blade, holds onto it, and eats it like a corn dog. The (flightless) nymphs like wet areas, grassy swales, stream banks and roadside ditches but the (flying) adults may disperse into pretty dry conditions.
GsGs practice sexual dimorphism – males are generally brown and most females are green. They are in the band-winged grasshopper bunch; the edges of their light-greenish hind wings have a slightly darker band. Alert BugFans may recall that the bunchgrass locust of previous BOTW fame has similar antennae, called ensiform, which means “sword-shaped” in Latin.
It’s the males we hear, creating sound by rubbing the inside surface of the back leg against rough veins in the front wing in a noise-making technique known as stridulation . Both the males and the females can also produce a buzzing sound by crepitation , which involves popping taut membranes between their wing veins as they fly. Crepitating flight is slow and butterfly-like and may include low-altitude hovering, but when something is after them, they can fly quickly and quietly. It’s thought that the males also make a specific sound that allows them to gauge and control population density within an area.
When they’re in the mood, male GsGs station themselves on vegetation overlooking relatively bare pieces of ground used as display areas. They use crepitation-flying to enter the “patch” and send out a “Yoo-hoo” to females. Females crepitate on their way into the area, and they may be followed by more males, also crepitating, resulting in a Summerfest-like congregation that often picks up and moves from patch to patch. If a male encounters another male, he signals “no dice” with silent “leg-lifts,” but a female shows the color stripe on her legs to signal her receptiveness and he tips his legs back at her. Females are the pursuers in this game, and they prefer larger/heavier males. The resulting eggs are laid in the ground in mid summer. One source suggested that the GsGs that remain in the damper habitat of the nymph are more likely to breed successfully.
And the BugLady’s second question? The vast majority of grasshoppers pass the winter as eggs, but the GsG is one of the few species that overwinters as a juvenile (which is why they are the first on the scene in late spring). It will be a while before there are herds of tiny, newly-hatched two-lined and red-legged grasshoppers, crickets, katydids and locusts in the grass underfoot. GsG eggs hatch a few weeks after being deposited, and by the time they tuck in for the winter (in a state called diapause), they’re in their 4th or 5th instar. The following spring, it’s probably the increasing photoperiod (day-length) that jolts them from their state of suspended animation rather than the temperature; they bask in the chilly spring sunlight. Southern GsGs just muddle through without hibernating and may produce 5 or 6 generations a year; northern GsGs may produce a second generation toward the end of summer when the day length returns to that of their breeding period in spring (like those maverick fall dandelions).
Go outside – listen.
The Bug Lady