Organic Strategies for Grasshopper Control
© Frances Michaels
Regardless of where you live in Australia, the noise of crickets and grasshoppers is one of the background
sounds of hot summer nights. The 'song' is produced by the male to attract a mate.
Crickets, grasshoppers and locusts, as a group of insects, are distinguished by strong chewing mouthparts
and enlarged hind-legs designed for jumping.
Crickets are usually nocturnal. Some species, like the tree cricket, are predatory, while others, like the
mole cricket, feed on roots and burrow in the soil.
Grasshoppers are divided into short and long horned, with the 'horns' referring to the length of antennae.
In long-horned grasshoppers the antennae are longer than the body. Long-horned grasshoppers are large, mainly
plant eaters and often nocturnal. Short-horned grasshoppers, including the locusts, are active during the day.
The name locust is given to species that can occur in swarms. This includes the Australian plague locust, which
has a black patch at the tip of the hind-wing and some scarlet on the hind-legs.
Not all grasshoppers are plant-eaters; surprisingly some are predatory with front legs adapted for grasping
prey. Check before you accidentally squash a 'garden helper' by looking for spiny front legs.
Grasshopper eggs are mainly laid in the soil, although some do lay eggs on leaves. The eggs lay dormant until
it rains, sometimes for years. Once hatched and if conditions are right, the next generation can be produced
within a month.
Crickets, grasshoppers and locusts attack a wide range of plants, but it is in inland areas where the major
impact is felt.
Physical and Cultural Controls
- The most important natural enemies of grasshoppers are birds. In inland areas the ibis is particularly
important as a control for locusts. As a result the draining of wetlands can increase locust plagues. You
can attract birds to your garden by providing a source of water and safe nesting sites, free from predators
and with privacy. Many small, insect-eating birds nest in the shrub layer rather than the tops of trees.
Preferred nesting sites are dense plantings of native shrubs, especially prickly ones, in out-of-the-way
corners of the garden. Make sure there are perches such as trellises or posts scattered throughout where
birds can sit and watch for insect prey.
- Water is an essential element to improve biological control. Small ponds encourage useful predators such
as frogs and dragonflies, which need water to breed. Frogs are very active nocturnal animals that devour
large numbers of pests.
- Chickens not only like eating grasshoppers, but seem to get a lot of entertainment catching them too!
Keen gardeners in inland areas should consider designing a chicken run with a shared fence between the chook
run and vegetable garden for as much of the garden perimeter as possible. This can reduce the fencing needed
and create a 'Fort Knox' style vegetable or flower garden as far as grasshoppers are concerned.
- Guinea fowl are hardy birds which eat large numbers of grasshoppers and ticks. Although their noisiness
makes them unsuitable for urban areas, they could be a big help on larger properties.
- Other creatures that prey on grasshoppers include lizards, spiders and predatory carabid and rove beetles.
These can be encouraged by providing shelter such as rocks and hollow logs. Small rock cairns can look
decorative in the garden and perform a valuable function of refuge for these predators. Baby grasshoppers
hatch in spring and early summer from eggs hidden just below the soil surface. As they like to hide in
dense areas of vegetation, they can easily become prey for hungry predators.
- Beneficial insects such as paper wasps, tachnid flies and parasitic wasps prey on grasshoppers. Robber
flies are a major predator of grasshoppers, (up to a third of their diet). Habitat, such as a border of
perennial plants, needs to be available all year round as a refuge for these predators. Growing flowering
plants in the garden or orchard as a pollen and nectar source helps to maintain a population of these
beneficial insects. Suitable insectary plants include
Queen Anne's lace,
Seed mixes of insectary plants are available commercially such as
Good Bug Mix or
Bed and Breakfast Seed Mix.
- There are a range of naturally occurring parasitic fungi species that attack and kill grasshoppers. These
include: Nosema locustae, Beauveria spp., Lecanicillium spp. and Metarhizium spp.
Least Toxic Chemical Controls
- As a variation on the old adage 'the early bird catches the worm', this is also a good strategy with
grasshoppers. Catching them in the early morning is relatively easy, as they are less active in the mornings,
especially after a cool night. Either catch them by hand or use a butterfly net.
- Some gardeners use a border of tall, green grass around the outside of the garden to trap grasshoppers
and (hopefully) divert them from vegetables or flowers. It only works if the trap crop is left un-mowed and
doesn't dry out.
- Digging or cultivating in spring, and leaving the soil exposed, can expose the eggs to predators.
- Physical barriers such as
floating row covers or mosquito netting
work very well for early-season protection. This will also protect your plants from other pests like fruit
flies and caterpillars. Sometimes exclusion is a lot of work initially but saves heaps of effort over time.
- The colour yellow is meant to be attractive to grasshoppers, so there are various ways this can be used
to trap them. Long sticky tape traps are commercially available. Dams, ponds, or children's paddling pools
can be used to drown grasshoppers by floating pieces of yellow plastic in the water, or suspending it from
bamboo just above the water. Fish will happily eat the grasshoppers, or they could be collected and fed to
chooks. You can try 'planting' a yellow bucket in the vege garden. Leave around 6 cm of yellow plastic
showing above the mulch. The grasshoppers are attracted to the colour and will jump in but can't climb back
out. Fill the bucket with water and a 10% molasses solution, cover the water with a film of canola oil to
deter bees and mosquitoes.
- Canola oil has been found to be a grasshopper attractant, and can be used to make baits more attractive
to grasshoppers - as with the above example. It could also be combined with organic insecticides to make
them more effective, and floated as an oil on top of water traps.
- Insecticidal potassium soap sprays such as
Natrasoap work best on small
- Neem is a botanical insecticide made from extracts of the neem tree.
Eco-Neem is a registered organic spray that
controls a wide range of insects including grasshoppers. It works in multiple ways with the two main actions
being suppression of insect appetite (they starve to death) and restricting growth (unable to moult
successfully). It is approved in Australia for use on ornamental plants only but would be particularly
useful sprayed on a trap crop of tall, lush grass.
- Pyrethrum insecticides are effective as a
grasshopper control but also may kill beneficial insects. Spraying in the early morning or late afternoon
will help to reduce the impact on non-target insects.
- Myco-Force™ is available as probiotic to
assist in the recovery of previously affected insect damaged plants. It contains naturally-occurring,
bio-balancing fungal species including: Beauveria bassiana, Metarhizium anisopliae, and
- Make up a chilli spray as a repellent - see Home Made Chilli Spray box, below.
Organic farmers can take advantage of a biological control for locusts and grasshoppers based on a naturally
occurring fungus Metarhizium
. This breakthrough has meant that preventative control by the Plague Locust
Commission can take place in environmentally sensitive areas without the problems caused by pesticide residues.
It is marketed as Green Guard® but is not currently available in Australia in home garden size packs.
Home Made Chilli Spray
Blend together half a cup of fresh chillies with 2 cups of water. Add a dash of dishwashing liquid to improve
sticking. If you have no chillies substitute with 2 tablespoons of Tabasco sauce. Always spray a small section
of the plant to check for leaf burn. Check in 24 hours and if there is no damage spray as needed. Leaf burn with
any spray is more likely to occur during hot weather.
Yellow Sticky Roll Trap