Other news: a new biological control agent

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© D.L. Johnson, Lethbridge.

The club-horned grasshopper (Aeropedellus clavatus) is a small, slant-faced grasshopper. It is one of the most common insects found on pastures in the spring and early summer, and is sometimes mistaken for early hatching of pest species. It is normally grey, black and tan, but it can be partly green and white. It can be recognized by the hourglass marking on the back (pronotum), the short wings (especially the female), and the knobbed antennae. The club-horned grasshopper is able to complete embryonic development at low temperatures. It hatches in April, earlier in the spring than any other grasshopper in Canada. All of the other grasshoppers found before May have overwintered in the active stages. Later in summer, the adult can be heard making a scritch-scritch-scritch sound (stridulation), which in warmer weather can be one continuous soft buzz. This grasshopper eats western wheat grass, needle and thread grass, and other grasses, but never requires control. [Non-pest]

The velvet-striped grasshopper (Eritettix simplex tricarinatus) is small, green or gray, with a sharply pointed head and two dark stripes highlighted by light-coloured stripes, running down the back. It is often found on grassy slopes and roadsides in April and May, not because it hatches early but because it overwinters as a hopper that resumes activity in the spring. If you use a guide to identify grasshoppers, it may indicate that this species is found only in the extreme southeast corner of Alberta, and in Saskatchewan near the US border, but don't believe it. In April, 2000, this species was the most common grasshopper present in the Oldman River valley near Lethbridge. Either because of lack of effort in the past, or because of the warmer weather lately, they now occur right across southern Alberta and Saskatchewan, up to about Oyen and Leader. Typical food for this species includes blue grama grass and sedge, but it eats so little that it causes no harm. [Non-pest]

The brown-spotted range grasshopper (Psoloessa delicatula) is one of the first grasshoppers seen in the spring. They lay eggs that hatch in summer, unlike the pest species, which lay eggs in late summer that hatch in the spring. You can recognize this species by the early date, grey colour (rarely green), constricted hourglass on the back, tiny colourless hindwings, and distinct black triangles on the back legs when seen from above. Like the club-horned grasshopper, the brown-spotted range grasshopper is important food for the nestlings of grassland songbirds. This grasshopper eats native grasses and sedge but it causes no significant damage, and there is no reason to take control action for this speces. It is best to avoid any grasshopper spraying in Canada before June 1. [Non-pest]

The speckled rangeland grasshopper (Arphia conspersa) is dark brown to almost black. Its preferred habitat is native short grass on sandy soil, where you can find it even in March. The immatures overwinter and begin feeding when spring temperatures reach 10-15 C. In May, this hopper fledges and flies across the Prairie on bright red wings with a buzzing sound (crepitation). Grasshoppers such as this one are called the band-winged grasshoppers, because the hindwings, which are hidden under the forewings (tegmina) while at rest, are coloured or banded. [Non-pest]

Some of the early-season grasshoppers are shown in this plain-language article: large PDF file suitable for printing, 10 Mb

Later in the year, there are more than two dozen other species with coloured wings, but the speckled rangeland grasshopper is the only one with bright red wings visible in the spring. The red-winged grasshopper, a similar relative, flies in the late summer. [Non-pest]

A good take-home message is that coloured wings or sound (singing, scratching, buzzing, clacking) indicate a non-pest species, at any time of the year. The long-horn grasshoppers (usually tree crickets or katydids ) that sing in roadside brome, pastures or even crops later in the summer are also no threat to agriculture. Range grasshoppers with brightly coloured hind legs (blue or red) are not pests. Any large grasshoppers seen in Canada before June 1 are no threat, but the small and abundant hoppers emerging in early June are almost certainly pest species if they are seen clustering together in patches (see below).

The northern green-striped grasshopper (Chortophaga viridifasciata) can be green or tan. It can be recognized by the strong ridge on the back, and the early date of its appearance. No other grasshopper in early spring has such a sharp ridge (but later in the summer, the green fool grasshopper, Acrolophitus hirtipes, has an even higher ridge). The northern green-striped grasshopper has a yellow wing in flight (rarely red-orange). It tends to fly only short distances, with rapid turns, so it looks like a butterfly. It is not common on the Prairies in summer, but can be found in the early spring. In late summer and fall, it appears as a small wingless hopper, usually grey, brown or green in colour. [Non-pest]

One of the largest grasshoppers on the Prairies is the red-shanked grasshopper (Xanthippus corallipes latefasciatus). It spends the winter as a bumpy immature that looks a little like a tiny toad. It can be brown, olive green, grey or tan. When it obtains wings, they can be either red-orange or yellow. This grasshopper is important food for grassland birds of prey, and other wildlife, including coyotes. Parasitic flies attack this species, at high rates. There are several similar-looking species later in the summer. [Non-pest]

The Mormon cricket (Anabrus simplex) appears in June in Canada. It is a long-horned grasshopper, related to katydids. This insect caused trouble for the Mormons in the mid-1800's, and in 2001-2003 it caused enough damage in the US that spraying costs reached up to US $6 million per year. In Canada, it is not cause for concern, despite its size.

The pointed structure (ovipositor, meaning egg-layer) at the back indicates a female. It may look like a stinger, but it is harmless to handle. The white mass attached briefly to the female is the spermatophylax, left during mating. The male rubs its wings together rapidly to sing a loud, long song from a perch such as a plant stem or fencepost. [Non-pest]

The most common grasshopper pests in the Canadian Prairies in 2001-2003 were the two-striped grasshopper, and the clear-winged grasshopper. Both of these can occur in large numbers and in some cases will eat crops down to the bare ground around the field margins or other choice spots. The Two-striped grasshopper has an effective detoxification system that allows it to eat a wide range of plants.Some plants, such as pigweed, wild millet and rose, are not eaten.

The two-striped grasshopper can be recognized by the stripes on the back. The adult is usually green with yellow highlights, but the immatures can be orange, yellow, green, brown or even magenta. In eastern Canada, the hind tibia are mainly red, and in western Canada the tibia are yellow and light blue. Dry weather increases survival and development rates (but they do drink water; click here to see them drinking from a cage screen). [Pest species, when damage is obvious and numbers exceed 13 per sq. m.]

The two-striped grasshopper often hatches 3 to 10 days before the other pest species. In most years, it first appears around May 26, but in cool years it can be delayed as late as mid-June, and continue to July. The immature is light brown, and appears fatter than other first instar hoppers. [Pest, when damage is obvious and numbers exceed 13 per sq. m.; I have seen up to 200 per sq. m. of this species.]

The two-striped grasshopper is susceptible to infection from a grasshopper-killing fungus (Entomophaga grylli) during warm, moist weather, as long as spores from previous infections are available to begin the process. E. grylli causes the infected grasshopper to climb to a position that is higher than usual a usual day-time roosting spot, and clasp the support tightly in death. An additional 6 other species are also infected and killed, but to a lesser extent. Another variant of this fungus infects the Clear-winged grasshopper. Although frequent rediscovery of this natural control agent often causes raises hopes, E. grylli is rarely the main cause of declines of outbreaks. Exceptions occurred in 1962 and 1977, when large numbers of grasshoppers were killed. I monitor this disease, and it is currently low on the Prairies (2000-2006).

Packard's grasshopper was common during the infestations of pasures and cereal crops during 1983-87 (I saw isolated infestations of up to 50 per sq. m., of this species). They were rare during 1999-2002, although other grasshopper species increased during this period. In 2003, Packard's grasshopper increased in pockets of south-eastern Alberta and Saskatchewan. The nymph, which normally hatches on the Canadian Prairies around June 1, looks a little like the Two-striped, but with black pepper spots on the back. [Pest, when damage is obvious and numbers exceed 10 per sq. m.; more common in sandy or light brown soils; readily feeds on alfalfa as well as cereals and pasture grass]

The lesser migratory grasshopper is the species that famously flew into Saskatchewan and Alberta from the US in the 1930s by the millions and caused immediate and subsequent outbreaks. It was a very common and active crop pest during 1984-87, but in recent years it has not been as common as the clear-winged and two-striped grasshoppers. In 2002 and 2003, it increased in Saskatchewan, but it is still relatively rare in Alberta. It is less susceptible to disease than the two leading crop pest species, and could emerge as a more serious problem in the long run, if climate trends continue toward warm and dry conditions. [Pest, when damage is obvious and numbers exceed 13 per sq. m.; good flier, in warm weather with light wind]

Grasshoppers are attacked by at least five diseases, several kinds of wasps, parasitoid flies, ants, spiders, predatory beetles and birds.

The diet of the clear-winged grasshopper is restricted mainly to cereal crops and grasses. It rarely eats canola or other broad-leafed plants. Like the other pest species, they overwinter as eggs and hatch in early June, so the date can help to separate them the harmless species that overwinter and emerge earlier. The adults can be recognized by the blotches on the forewings. the males is yellow-brown and the female is a duller brown and tan. They can fly long distances, when weather is warm and clear. [Pest of grass and cereal crops, when damage is obvious and numbers exceed 13 per sq. m.; densities of up to 90 per sq. m. have been common in recent years. The highest verified density that I personally saw was 800 per sq. m., south of Youngstown, AB, June 9-10, 2003].

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.]

More details on the Carolina grasshopper

The clear-winged grasshopper and the Carolina grasshopper are both susceptible to the fungus E. grylli, but it is not the same pathotype as the one discussed above, which affects the spur-throated grasshoppers (such as the two-striped grasshopper). The life cycle of the microbe and the symptoms as the disease are also different. A conidiophore (left) forms on the surface abdomen and produces showers of conidia (pear-shaped spores shown at right) that germinate and infect other grasshoppers.

More details on the Carolina grasshopper

There are more than 60 other interesting species of grasshoppers that you can find in the Prairies, and an additional 15 or so that occur in montane and alpine environments. An additional 10 or so are rarely encountered but may appear when weather changes. I have photos and observations on most of them, and will post these if there is interest. I will produce a brochure to montane species in 2004 and one for grassland in 2005. [Shown are the Large-headed grasshopper and the Four-spotted grasshopper, which cause little or no significant damage in Canada.]

Visit the site below for more on other insects.

Click an insect in the drawings shown at: BugGuide.Net

Collecting tip:

Ziploc bags, the kind with breathing holes, are GREAT. Click here.

More detail on additional species is available on the "K-4 version", for young naturalists (some of the information is also good for older grades, but I tried to make it interesting for the Kindergarten to grade 4 group as well).

This is a picture guide to some of the kinds of grasshoppers that can currently be found in the Canadian Prairies and Northern Great Plains. Insects (including grasshoppers) vary greatly in abundance, and what you can easily find in a walk with a net can change over a season, or over a short number of years. Some species that are common for several years become uncommon, and previously rare species might increase. The changing list means you might not know what to look for, when you go for a hike and try to recognize the species that are found at a given time and place, or when you scout agricultural land with the intention of separating non-pest species and potential pest species. The guide below will help you spot the main species that are currently common in the northern Great Plains and Canadian Prairies.

This is only a short list. If there is interest, I will post photographs to aid recognition of grasshopper species and instars (and maybe other organisms) that will be found in grasslands, foothills and montane zones, as the season progresses. A grasshopper identification and natural history handbook will be available in 2005. Information can also be found on grasshoppers of other regions (Florida, Colorado, Wyoming, Colorado, North Dakota, eastern Canada, and other places), but species, appearance, dates and habits may vary. Research articles concerning details of the ecology, biochemistry, control, biogeography, etc. are also available, but this guide is meant for naturalists, students and growers.

Dan Johnson, 2004

The following articles are intended for non-specialists. These short guides contain photographs and information on pests and non-pests. You can download the PDF files and make copies. When you quote from them, refer to the articles as shown in the titles below.

 

Johnson, D.L. 2003. Slant-faced grasshoppers of the Canadian Prairies and Northern Great Plains. Arthropods of Canadian Grasslands 9: 5-16. Published by the Biological Survey of Canada, Ottawa. Download PDF (or download reduced size PDF, suitable for screen-viewing).

Johnson, D.L. 2001. Band-winged grasshoppers of the Canadian Prairies and Northern Great Plains. Arthropods of Canadian Grasslands 7: 5-12. Published by the Biological Survey of Canada, Ottawa. Download PDF. Sorry, this file was not loading for a while, but I reloaded it and it seems to be ok now.

Johnson, D.L. 2002. Spur-throated grasshoppers of the Canadian Prairies and Northern Great Plains. Arthropods of Canadian Grasslands 8: 16-25. Published by the Biological Survey of Canada, Ottawa. Download PDF.

Johnson, D.L. 2005. Long-horned grasshoppers, katydids and crickets of the Canadian Prairies and Northern Great Plains (coming later).

Johnson, D.L. 2004. How to scout for pest and non-pest grasshoppers. Grainmagazine, Diseases, Insects & Weeds 2004: 32-33. Farm Business Communications, P.O. Box 9800, Winnipeg, MB, Canada, RC3 3K7. Download: large PDF file suitable for printing, 10 Mb

Grasshopper Management, AAFRD Agdex 622-27 (low-res version) A practical guide, with more photos.

Early spring grasshopper identification guides:

Helen Schuler Coulee Centre spring grasshopper guide (with notes for Lethbridge)

Police Point Park spring grasshopper guide (with notes for Medicine Hat and Swift Current)

Movies of grasshoppers basking, eating, etc.

Click here for
Canadian Geographic Grasshopper Learning Fun (prepared by Canadian Geographic, not by DJ, but recommended)

Discovery Channel, Locust interview on the Web, (Sept, 04; Daily Planet, www.exn.ca; see "Feeding frenzy")