Montana Field Guide

The following comes from Snodgrass (1905), Gurney (1939), Helfer (1971), Vickery and Kevan (1985), and Capinera et al. (2004). The most obvious feature of this species is its rough, pebbly (carinate) pronotum. They are fat, full-bodied insects, short-legged, colored reddish-brown or an apple-green. Abdomen is yellowish-brown with bold spots on each segment. The ventral edges of the pronotum possess a yellowish stripe. The female ovipositor is much longer than her hind femur and curved slightly upward toward the tip.

Calling song description
Snodgrass (1905) describes the songs of the Coulee Cricket as “The usual chirps of the male are uttered in regular and rather slow succession, averaging between 90 and 100 chirps a minute. One [male] stridulating for three minutes, made 97, 97, and 96 chirps a minute, respectively. When disturbed, they stridulate sharply and rapidly in short, quick series of chirps having a decidedly angry tone.”

This species overwinters in the egg stage. Nymphs hatch mainly in April, but some observations have found them occurring as early as March on sheltered, southerly exposures. Adults occur from May to July. The late-instar nymphs form bands and make migrations in April, May and June. Few, if any, individuals survive longer than mid-July (Snodgrass 1905, and Vickery and Kevan 1985).

The following is taken from Snodgrass (1905), Gurney (1939), Helfer (1971), and Vickery and Kevan (1985). Male and female body length is 32-38 mm, and male pronotum length is 7.9-9.5 mm, and for females, 7.5-10.5 mm. The male cerci is stout, depressed at the tip, bearing a short, incurved spine (see illustration). The female ovipositor is 20-24 mm. The front tibia has 4 to 5 spines along the hind margin. The hind wings (tegmina) are short, overlapping, convex, and black with yellow margins. The female wings are reduced to lateral pads and hidden by the pronotum.

The Coulee Cricket is the only species in the genus Peranabrus but can be confused with almost any of the Shieldbacked Decticids.

The common name “Coulee Cricket” is due to this species’ preference for habitat sites in drainage valleys or ravines termed “coulees,” occupying elevations from 6,000-8,000 feet (Snodgrass 1905, and Vickery and Kevan 1985).

The Coulee Cricket consumes mostly vegetation and will favor Fringed Sage (Artemisia frigida) when available in dry sagebrush areas. This species has also been observed to have a liking for flesh if available. In its absence, they resort to cannibalism, whereby one or more individuals will devour another disabled kin in its late instar and adult stage, even before it is completely dead. They seldom, if ever, attack or disable a healthy individual (Snodgrass 1905, and Vickery and Kevan 1985).

Mating occurs only in the morning between 10 AM to 12 PM. The male stridulates continuously while advancing backward and obliquely sideward towards the female’s head and tries to push his abdomen under the female’s. If accepted by the female, the male clasps her with his cerci, the female lowers her ovipositor ground ward, bringing her bursa copulatrix (genitalia behind the 8th abdominal segment) against the tip of the male’s abdomen and the male passes a bilobed spermatophore. The pair separate with the spermatophore attached to the female. After the sperm passes to her spermatheca, she eats the spermatophylax. In late afternoon, a female begins to lay her eggs and continues to do so late into the evening. During ovipositing, most females assume an upright position standing on her hind legs and grasping a small clump of grass blades with her other front pair. She forces her ovipositor into the ground at the base of the grass clump using strong wave-like contractions of her abdomen to lay a single egg, then removes the ovipositor. She may reinsert the ovipositor in the same hole and place another egg beside the first one (sometimes a few more). More often, she moves a short distance, drills another hole and continues the ovipositing process as stated above. She continues this maneuvering, laying more eggs around the grass clump’s roots. The eggs are not enclosed in a covering case, each being entirely free and separate from the others. An individual female deposits approximately 40-80 eggs. After completion, she weakens and dies the following day, often consumed by others in her band (Snodgrass 1905, and Vickery and Kevan 1985).

Like the Mormon Cricket (Anabrus simplex), this species lives in bands numbering into the hundreds, even thousands. In most places within their geographical range, they generally occur in dry, wildland habitats where there is little in the way of economic important vegetation for them to destroy. Some bands are migratory and move in “marches” much like A. simplex and can cause similar destruction to alfalfa, wheat, field crops, vegetables and some tree foliage. No recent outbreaks have been reported for this species in the literature nor the media. Damaging outbreaks reported occurred in Washington between 1910 and 1920, and another report of damage to grasslands in British Columbia in 1972 (Vickery and Kevan 1985).