The sound of crickets and grasshoppers is coming

This heading sure seems to indicate it’s summer.*

A CSIRO textbook of 1970 tells me there are over 1500 Oz species in this group. You’ll be pleased to know I’m going to generalise on only a few of them. You’ve no doubt seen different shapes and colours of grasshoppers from cute little green ones and some brownish like the illustration, that are getting up to 100mm (4”) long… so big that you can actually hear them munching.

Some have antennae that are short; another family is the long-horned grasshoppers with antennae much longer than their body. The Australian plague locust is about 50mm long, including wings, has the short antenna, but the easiest way to identify them comes from noting the darker patch at the extremity of the hind wing.

Most grasshoppers can make that throbbing, pulsing, strident noise you automatically associate with summer… because they have stridulation organs! Not quite a violin but similar action as tiny ‘teeth’ on the hind legs are scraped across the edge of the forewings. Different sized teeth and wings of different species make different sounds that specifically ‘turn on’ the females of that particular species during courtship.

Don’t rely on that noise to tell you when grasshoppers have arrived in your crop. There’s no noise from young hatchlings and even the larger nymphs that keep getting bigger as they go through a series of moults (and the wings get more noticeable in the last two moults).

That silence means they can do a fair bit of damage before you notice them. Another bit of sneakiness: they usually are very aware of people (and bird) movement and will quickly move around to the other side of a leaf or branch to avoid being seen… much the same as leafhoppers.

Reproduction might be different to what you expect. Sperm is transferred to the female in spermatophores like a full condom and, as the eggs come out and past the sac, they are fertilised.

Most grasshoppers lay hundreds of eggs in the soil. Hatching nymphs of some types have a row of ‘teeth’ on the top of their head which they use to abrade their way out of the eggshell. These ‘teeth’ are gone with the first moulted shell.

The wingless nymphs eat grass and low vegetation and don’t usually bother tree crops until they can fly – unless they’ve walked/hopped from nearby pasture or your inter-row areas and climbed up.

There’s various species and a varying number of moults to become adult… and a varying timeline to get there. Length of lifecycle is also dependent on season and available food. If food is getting short (such as from drought) the population dwindles due to competition for food, but the time can also be extended for the same reason.

Twelve months or so is not unusual. For plague locusts, once they are winged adults, they may swarm to get away from the food shortage (they created) and clouds of them can travel at height for long distances… until they can see green down below. Green vegetation (including a green cotton T-shirt on a clothesline) is appetising enough reason to head back to earth. That is a plague.

There are some short antennae grasshoppers with long, narrow bodies that prefer water plants such as sedges and rushes. If you have a billabong or pond near your orchard for irrigation, these ‘hoppers’ can move into your crop for a change of diet.

It’s not unusual to see five-legged grasshoppers; if you try to catch one and only get to pull its leg, there is a ‘fault line’ between the femur (the muscular segment nearest the body) and the rotator ‘stump’ and it will come off in your hand!

I suppose this is a built-in survival mechanism against bird attack; bird swoops in for the body, big jump from the ‘hopper and the hind legs are the last to leave the scene… literally.

Control is either to use contact insecticides once they are eating crops and from aircraft if there are big swarms in the sky. Semi residual insecticides, mostly synthetic pyrethroids, are registered for use on pastures (but not near waterways) to kill hatching nymphs and older nymphs. Livestock have to be kept off for a short withholding period.

Crickets

They are not all like Jiminy. They also are not a major problem for tree crops but many tree croppers have a home veggie garden and might like to know what eats seedlings almost as soon as they’ve germinated… and to strident music. Yep, Crickets.

To simplify, there are mole crickets (pictured below) and field crickets (pictured in title). Mole crickets have shortish antennae, a bulging thorax and big forelegs designed for pushing soil sideways. Good for digging. The hind legs are not for jumping but they still have the accessories to make music when rubbed against the forewings which go only halfway to cover the abdomen.

Field crickets are mostly all black, antennae almost as long as the body, wings that cover the abdomen, normal forelegs but jumping hind legs… and they make that summer sound: a throbbing musical dirge, around dusk.

In daylight, both types of crickets stay in hiding in the soil, mulch, under debris and under bark. Once it’s dark, they emerge to forage for (preferably) new growth. Both crickets lay eggs in the soil and mole crickets will also eat fibrous roots as well as above-ground young foliage.

Control

Spray contact insecticides after dark.

Earwigs (pictured below)

These are pests in bunches of fruit such as cherries, sometimes apricots and certainly grapes. They are not from the same insect Order as grasshoppers and crickets but, they are similar in habits to the field crickets.

Eggs are laid in the soil, a few moults to become adult and then to await sundown to climb trees, abrade the fruit and eat the juices. Sometimes they may stay up above ground level during the day, hidden from view in the rough bark or closer to their tucker in bunches of grapes or clusters of fruit, kidding it’s dark.

Control

Spray contact insecticides after dark. When fruit is close to harvest natural pyrethrum has only a 1-day withholding period and could be the one to choose.

*Article written by Ion Staunton, an entomologist and owner of Pestech Australia – manufacturer of PyBo Natural Pyrethrum Insecticidal Concentrate. Any questions? Contact: ion@pestech.com.au

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