More about the Carolina grasshopper (also called the black-winged grasshopper; other regional common names include the roadduster, the Carolina locust, and the butterfly grasshopper).

The Carolina grasshopper (Dissosteira carolina) is a large grasshopper that flies like a butterfly and seems to disappear when it lands on bare soil. It is not normally a pest, but in places where the soil is so fine that it blows, this grasshopper can build up and cause minor damage to wheat or pastures. It usually looks much worse than it is, because of its size. It normally doesn't fly until July. This species does well in very light soil. [Usually a non-pest, but may cause damage to cereal crops if numbers exceed 10 per sq. m.

(All photos and text copyright Dan L. Johnson; photos and text may also appear in future guide books and websites by DJ)

Immature Carolina grasshoppers are typically tan or grey, but in rare cases they can be chalky blue, moss green or even orange to rose, like the fifth-instar immature above. This hopper is about a week away from molting and obtaining two membranous, black hindwings and two leathery forewings.

Note: chalky rose or bluish immatures of this shape are not all Carolina grasshoppers, and may be confused with Circotettix rabula, the wrangler grasshopper, or C. carlinianus, the snapper grasshopper (regionally sometimes called the rattlesnake grasshopper). These two species do not have the deep cut in the pronotum (top of the thorax), like the Carolina grasshopper does. A comparison of the adults is shown in this summary of common band-winged grasshoppers .

Adult Carolina grasshoppers sitting on warm stones on a cool day.

The female is larger than the male, as with most grasshopper species. The Carolina grasshopper reaches the adult stage in late July in Canada, and much earlier (May to June) in the southern US. In the photo, the male sits on the female's leathery forewings (tegmina; one forewing is a tegmen) and drapes his abdomen over her right side, coming up from the side and below to connect in a J-shape. The paired hooks on the tips of the male's front (prothoracic) and middle (mesothoracic) legs hold the edges of the female pronotum (the saddle-shaped top of the thorax), the tegmina or the ridges of the upper surfaces (tergites) of the segments of her abdomen. During this time, the female does the walking and jumping, if required.

In ancient times insects probably mated end-to-end, and the modern grasshopper modification of twisting allows them to sit as a unit facing the same way. This position is more convenient, despite the jury-rigged appearance, and offers advantages for feeding, sunning, escaping a predator and defending against others competing to mate.

The position during copulation is shown by these two-striped grasshoppers, another common species ().

Two-striped grasshoppers, illustrating the current method of mating.

The freshly fledged adult grasshopper is pale until it dries. This female Carolina grasshopper molted about 30 minutes before the photograph. (Fledging means obtaining wings.) The image of the molting two-striped grasshopper below shows how most most long-winged grasshoppers molt from the last immature stage (of 5 or 6) to the adult stage. The wings are pumped full of blood (insect hemolymph) to expand them from their former shriveled state.

Two-striped grasshopper molting. The four wings are unfolding,stretching and filling. Note that the legs have been pulled from their previous outer covering, leaving a replica behind.

I've spread and dried the wings of these adult Carolina grasshoppers to show the pale yellow stripe on the hindwings. The pattern and the flight behaviour, which includes fluttering and dipping from side to side, makes this species appear to be a butterfly (which probably convinces some birds to give up the chase early).

Black-winged grasshoppers flying near Turin, Alberta. There are about 20 Carolina grasshoppers visible in this photo, but when I took the image I noted that I could see typically about 80 on the wing at a time, within 10 m of me.

This species is abundant in the northern grassland only in warm, dry years, and is most common in local zones with fine, drifting soil. It is not a significant crop pest, but could become one if longer drought in the future result in dry conditions and more powdery soil surfaces in brown and light brown soil zones.

The larger female is wrapping a Carolina grasshopper captured in a web strung between tall stems of grass.

In warm, moist years, populations of the Carolina grasshopper are partially limited by infections caused by the fungus Entomophaga grylli. The adult female above is dying, and has assumed the characteristic posture of a grasshopper infected by this fungus. The legs hook the cadaver to vegetation or other above-ground position, from which the spores of the fungus can spread.

The grey ridges on the segmental lines of the abdomen are fruiting bodies (conidiophores) of the fungus. The large hole is not caused by the fungus. This is the tympanum or auditory organ, which is essentially the grasshopper's ear. It is always on the first abdomenal segment. The ear of this grasshopper has opened because of the infection and dessication of the cadaver.

The head of a grasshopper killed by the fungus E. grylli typically turns milky white and shell-like. This male Carolina grasshopper was killed by the fungus (note the leg positions, bent into hooks before death.)

After death, the grasshopper cadaver remains attached to an elevated point, and slowly degrades, as the spores are produced and distributed by wind or rain. We have experimented with collecting and using the spores as a control agent, but the process of keeping them viable and capable of re-infecting is complicated and usually not effective. In the late 1980's, I had success in growing the fungus in liquid cultures in fetal bovine serum and Grace's tissue culture medium, using standard methods, but it was not effective for grasshopper control in this nearly cost-free "out of the box" source. Development of more refined methods would be expensive, and other fungi are considered to be better candidates (for example: ; PPT).

The spores (conidia) from an infected grasshopper. This pathotype of this fungus produces pear-shaped spores that germinate and infect other grasshoppers, if conditions are right. (Photograph with Nikon Nomarski Differential Interference Contrast microscope, 400X; the spores are typically 20 to 30 microns in diameter; D. Johnson)

This primary conidium has germinated and produced the filament on the left side of the old spore shell. The cell contents has moved into the new tube, and the hyphal filament begins to grow. Soon the growing web of hyphae will be infecting and thickening the fluids and organs of the grasshopper, somehow causing the climbing behavior and then death. (Photograph with Nikon Nomarski Differential Interference Contrast microscope, 400X; the spores are typically 20 to 30 microns in diameter; D. Johnson)

Other fungi are being developed to serve as alternatives to chemical insecticides in some situations. This grasshopper above was killed by an Alberta isolate of the entomopathogenic (insect-infecting) fungus Metarhizium anisopliae var. anisopliae. Research is underway (or proposed, if funded) to develop this naturally occurring fungus as a pest control agent, and to determine whether it is environmentally safe, effective, economical, and reliable for applications against grasshoppers when their activities reach damaging levels, and to develop numerical models that will predict the best conditions and methods for applied use. Studies in 2006 and 2007 are funded by the Alberta Crop Industry Development Fund, and the Biopesticides Initiative, Agriculture and Agri-Food Canada Pest Management Centre. Additional resources are provided by the University of Lethbridge, Canada Research Chairs, and the Canada Foundation for Innovation. Click here for more images of the Alberta isolate of the entomopathogenic (insect-infecting) fungus Metarhizium anisopliae var. anisopliae.

Entz, S.C., Kawchuk, L.M. and Johnson, D.L. 2006, in press, Biocontrol. Discovery of a North American genetic variant of the entomopathogenic fungus Metarhizium anisopliae var. anisopliae pathogenic to grasshoppers

Entz, S.C., Johnson, D.L., and Kawchuk, L.M. 2005. Development of a PCR-based diagnostic assay for the specific detection of the fungus Metarhizium anisopliae var. acridum in grasshoppers. Mycological Research 109: 1302-1312.

Johnson, D.L., Smits, J.S., Jaronski, S.T., and Weaver, D.K. 2002. Assessment of health and growth of ring-necked pheasants following consumption of infected insects or conidia of entomopathogenic fungi, Metarhizium anisopliae var acridum and Beauveria bassiana, from Madagascar and North America. Journal of Toxicology and Environmental Health 65: 2145-2162.

Lomer, C.J., Bateman, R.P., Johnson, D.L., Langewald, J., and Thomas, M.B. 2001. Biological control of locusts and grasshoppers. Annual Review of Entomology 46: 667-702.

Smits, J.E., Johnson, D.L., and Lomer, C. 1999. Pathological and physiological responses of ring-necked pheasant chicks following dietary exposure to the fungus Metarhizium flavoviride, a biocontrol agent for grasshoppers in Africa. Journal of Wildlife Diseases 35: 194-203.