Grasshopper Seminar

A basic outline of what you need to know to

• recognize pest and non-pest grasshoppers, so that you can take the right action when you need to, but only when you need to

• anticipate the timing of the hatch, growth and risk to crops

• understand the role of weather, soil, crops and natural enemies, in causing grasshopper outbreaks to either increase or decrease in severity

All text and photos by Dan Johnson, University of Lethbridge

Eggs are laid about an inch into the soil, in late summer.

They are typically the size of large grains of rice.

A coarse screen can be used to check for eggpods. They are about the size and shape of macaroni, and have a foam plug at the end of the eggs.

year DD12 soil 5 cm

cumulative rain mm

1988 268 451989 101 1091990 77 1061991 129 911992 213 311993 147 821994 525 1361995 91 2241996 76 341997 106 1211998 261 1161999 145 1132000 237 372001 227 502002 100 2172003 142 135

Spring soil heat controls grasshopper hatching.

Pests hatch between May 25 (warm spring) and June 15 (cool spring).

At left: degree-days above 12 C, at Lethbridge. For this location:

• the 2002 hatch was June 15, and later.

• the 2000 & 2001 hatches were May 25-31.

Grasshopper eggpods

Eggs can be soaked in dilute bleach and examined. Eyes indicate that development is under way. A darker hopper embryo indicates that the eggs are close to hatching.

Underdeveloped Partly developed Ready to hatch

Newly hatched grasshoppers (end of May, and early June) are very small, but have a hopper appearance. Leafhoppers are more bullet-shaped.

Hatching can continue for weeks.

Not grasshoppers

Published by the Saskatchewan Pulse Growers, with the financial support of Agriculture and Agri-Food Canada’s

Pesticide Risk Reduction Program (Pest Management Centre, http://www.agr.gc.ca/prrmup)

Some types of grasshoppers hatch in summer, not spring, and overwinter in an active form, rather than as eggs in the soil.

These species can be found in March and April. They are never pests.

brown‑spotted range grasshopper

The clear-winged grasshopper is black-and-white at first (end of May), and then chocolate-brown later in June and early July.

A serious pest of barley, wheat and grass.

The two-striped grasshopper is tan when it first hatches, near the end of May (but may be delayed by cool, moist weather).

A serious pest of pulses, oilseeds, barley, wheat and grass.

Two-striped grasshopper

Sampling in spring or later in the summer is more accurate with a net.

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From a mathematical model of sweepnet use, but Eric Johnson

To use the sweepnet effectively, walk rapidly forward, while swinging the net widely, near the top of the crop.

Newly hatched two-striped grasshoppers are pale, and over the next few weeks turn brown and then often green.

This serious pest species molts and becomes darker yellow-green, with stripes on the back.

Breeding and egg-laying begin in July and continues into the fall.

Packard’s grasshopper is lime-green, with pepper spots, in June, and darker in July. It feeds on a mix of grasses and broadleaf crops, and readily damage pulse crops and canola.

This species is usually tan, but can appear very dark when nearly mature. In all stages, it has a stripe on the side of the head, and usually broken bands on the legs.

lesser migratory grasshopper, a pest of pulse, oilseeds and cereals

Clear-winged grasshoppers are so-called because they are in the band-winged family of grasshoppers, but their hind wings (visible in flight) are clear. They are not serious pests of broadleaf crops, such as pulses.

Barley crop removed by clear-winged grasshoppers.

Coronation, AB. Aug 29, 2002.

Immature clear-winged grasshoppers are first black-and-white, and then dark brown. They damage mainly cereals and grasses.

In late summer, clear-winged males are yellow, and the females are brown.

This species can sometimes be recognized by the unusual mass breeding concentrations, unlike other grasshopper species, which breed in pairs.

Some band-winged grasshoppers have red, green, yellow or orange wings in flight (the hindwings are hidden when they are at rest. These are never pests.

speckled rangeland grasshopper

northern green‑striped grasshopper

red‑shanked grasshopper

 Any grasshopper flying before June is not a pest.  Any grasshopper with hind wings highly visible in flight (red, yellow, orange or black) is not a pest.  Any grasshopper that sings, calls, clacks, clatters or makes other similar sounds, either in flight or on the ground, is not a pest.  Any grasshopper that inhabits a crop on a warm day without feeding on the vegetation may be a temporary resident that is moving to more preferred vegetation. Some species feed only on range and pasture, and may not move into crops. Monitoring may be required to detect movement.  

Large, usually green katydids have long antennae. They may have long egg-laying organs and sing loudly. These are never pests, on the Canadian Prairies.

Increases in their numbers do not necessarily indicate a bad year for pest grasshopper species.

Gleb

Some insects may develop resistance to insecticides,

or they may naturally have stages that are not susceptible.

We will discuss control methods and best practices.

• Chemical control methods. In Canada, provincial government websites and guides contain the latest recommendations.

• All grasshoppers are highly susceptible to pyrethroid insecticides (such as Matador and Decis), certain organophosphate insecticides (such as Lorsban) and carbamate insecticides (such as Sevin XLR). Baits (such as wheat bran containing small amounts of insecticide) are effective ways to control grasshoppers with lower rates of insecticides, when application conditions and equipment allow.

• Biological alternatives are under development.  

• Cultural Control Methods • crop and cultivar selection (partial resistance to feeding)  • early seeding • timing control measures (better early warning is being developed)• weed control (can reduce egg-laying and survival of the

hatchlings) • trap strips. Hungry grasshoppers move rapidly and far to find food,

and then stop at the discovery of acceptable plants. Grasshoppers drawn to the trap strips can be economically killed with insecticide.  

• In some years, natural enemies of grasshoppers reduce numbers substantially. These can include beeflies, fungal diseases, predators, and parasites (mainly flies that kills grasshoppers).