Mole Cricket - Gryllotalpa sp.

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Mole Cricket - Gryllotalpa sp. 

Mole Crickets live in underground burrows, where the male will call the female by positioning himself at the entrance and instead of singing to the outside, will turn around and sing back into his burrow; this unusual procedure not only amplifies his call, but also lets the female know if the burrow is moist or dry. This is important as females prefer a moist burrow to lay her eggs and a male with such endowed real estate will more readily attract a mate. 

There are eleven Australian Mole Crickets, which range over much of the country, but due to the female’s preference for moisture, they generally are more common in well-watered areas, especially irrigated lawns. The female will remain with the eggs until they hatch and even show maternal care by protecting the young nymphs. 

The heath around Esperance is predominantly a dry habitat, but there are many swampy areas that slowly drain from one area to another, which I presume is what attracts these insects, although I seldom encounter them. The photographed male above has undeveloped wings and never flies, whereas the female has fully developed wings and can move around freely, being guided by the loud calls of the male, which she does on warm summer evenings after or with the promise of rain. 

The strong fore-legs are specifically adapted for digging and used to reach the roots of plants on which it feeds, therefore Mole Crickets have little reason to leave their burrows other than for mating or escaping predators like spiders and large centipedes. However there is another and more dangerous predator, that being a large wingless metallic blue wasp commonly called a ‘Blue Ant’ which after paralysing the cricket with her stinger, will deposit an egg whose larvae will consume it after hatching. The female Blue Ant is around 2.5 cm (1’) in length and just a little shorter than the Mole Cricket, which is closer to 3 cm. 

Gryllotalpa is the only genus of the Gryllotalpidae family.

Field Cricket - Lepidogryllus sp.

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Field Cricket - Lepidogryllus sp.

Field Crickets belong to the Gryllidae Family and are known as true crickets because they represent what most people regard as crickets ie ground dwelling, darkly coloured and renowned for their enthusiastic chirping on mild summer evenings. Family species number in their hundreds and are found Australia wide. Gryllidae is part of the Grylloidea Superfamily along with the impressive looking Mole Crickets and are recognised by females having long cerci and a straight ovipositor.

These crickets are mainly nocturnal and hide during the day under or in logs, rocks, burrows, etc. Their diet is described as omnivorous, so if it can be subdued and tastes all right, it will probably be eaten. According to Dr David Rentz who kindly identified this species, there are two species that are identical in appearance and can only be separated by the speed of their chirping. L. comparatus is the slow chirper, whilst L. parvulus the faster.

Field Crickets favour warm moist environments, but around Esperance especially during summer, this is rarely the case, which means they are not very common in the district, although appear to be quite widespread. The ones above on a gravel background are from an inland mallee region north of Esperance, whilst the others were encountered in near coastal heath.

Apterogryllus species - Gryllidae

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Apterogryllus sp. - Gryllidae

Gryllidae is the largest cricket family and the members are known as the 'true crickets' when compared to other Orthoptera families. The genus Apterogryllus is an endemic one and collectively known as Wingless Burrowing Crickets, as they make extensive burrows and spend much of their time there. Their vertical burrows are 30 cm (12") or more in depth, with an enlarged living and vegetative storage chamber often with one or more side tunnels. During the heat of summer the entrance is sealed off, leaving the cricket safely entombed to emerge after seasonal rainfall.

The Australian Faunal Directory lists 20 Apterogryllus species, of which most were described or revised during the 1980's. From the distribution of these species, it is clear they are primary a tropical group, being largely found in the Northern Territory and Queensland. In Western Australia there are only 4 described species and all were collected from the far north of the State.

As these crickets are wingless, it is thought with their limited means of migration and sedentary lifestyle, various groups could easily become isolated to evolve into numerous localised species. If this speculation is valid, then the southerly distribution of the Apterogryllus species above, may mean it is undescribed

The photographs of the above male burrowing cricket were taken in late March, a time when the first rains often begin to fall and although these are not sufficient to cause flooding in our local sandy soils, it could have stirred a cricket predator requiring the cricket to flee for its life, or as I suspect, he was seeking a female wingless borrowing cricket, as is common with many burrowing male spiders at this time of year, who take advantage of pleasantly warm and humid nocturnal conditions.

My thanks to Dr David Rentz for identification.

Leponosandrus lepismoides - Anostostomatidae

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Leponosandrus lepismoides - Anostostomatidae

Anostostomatidae is another cricket family thought to be of Gondwana origin, with most genera restricted to the southern hemisphere. In New Zealand they are represented by several endemic weta cricket groups including the Giant Wetas that can reach 10 cm or 4" in head/body length, which are considerably larger than Australian family representatives. Of the Leponosandrus genus, L. lepismoides is the only species, but is widespread in Australia. However, I have not found it to be particularly common in the Esperance region, although this may be due to my limited nocturnal observations and it may be more common elsewhere in the district.

These crickets are also known as King Crickets and are represented by several Australian genera and include others where professional opinion differs, or where further research is required, so like others in the Orthoptera Order, there is much to keep entomologists occupied for years to come.

The diet of King Crickets is quite diverse and includes extensive hunting and scavenging of most animals within its size range, they will also consume many soft organisms, including herbs, fungi and fruits, so they are quite high on the invertebrate food chain, although they too fall prey to large spiders, night birds and small predatory mammals.

Leponosandrus lepismoides is around 3 cm in head/body length (little over 1") and I have only seen them in October, although they must be around at other times, but probably in a more productive location. This I would imagine to be around ephemeral swamps and flood plains, where their preferred food types would be more readily available.

My thanks to Dr David Rentz for the identification

Gryllacrididae species B - Raspy Cricket

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Raspy Cricket - Gryllacrididae sp. B

This Raspy Cricket is much smaller than Gryllacrididae species A, the other common local species (http://esperancewildlife.blogspot.com/2009/08/gryllacrididae-species-raspy-cricket.html), being less than 2 cm (1/2") in length, but although smaller it has incredibly long antennae of around 6 times its head/body length. Why it should need them this long is to me a mystery. although I have watched them feeling into every crevice as they move slowly along when on the ground. Presumably if it encounters a lurking predator, it at least has a 6 body length start, which may explain why the antennae of some crickets are broken. However, the larger huntsmen spiders seem to catch a few.

Disregarding the size difference between this species and Gryllacrididae species A, there are other differences that a close look will reveal. The egg laying ovipositor of the females is the most obvious, being long and straight with species A, but shorter and curved with species B. Also the mating male of species A, grasps and grimly hangs onto the female's ovipositor, whereas species B hardly touches it. Maybe the additional weight of the larger species requires it to gain additional support.

This smaller cricket appears to be more secretive than the larger one and is usually only encountered during March/April when they are commonly seen and heard calling for mates, but rarely noticed at other times as is the larger Raspy Cricket.

Gryllacrididae species A - Raspy Cricket

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Raspy Cricket - Gryllacrididae sp. A

The crickets in this worldwide family are not well known with the last major Australian review published in 1990 by Rentz and John. The Australian Faunal Directory lists 28 genera and almost 100 species, but estimates suggest the number of species is closer to 200 and worldwide 600, giving Australia about a third of the total family population. Gryllacrididae is primarily a southern hemisphere family with only a few species occurring north of the equator, thereby providing strong evidence for a Gondwana origin.

Many species dig vertical burrows and line them with a silken substance they produce from their mouths, others use this substance to make shelters by gluing leaves together. They are nocturnal and being omnivores, venture forth at night to hunt small invertebrates or to feed on vegetation or detritus. Interestingly, there is evidence that they use the stars to navigate the way back to their shelters.

From an ecological point of view, these crickets play an important role in the food chain and although they are predatory themselves, they are commonly preyed upon by larger animals, particularly mammals and the larger spiders. Another feature of the Gryllacrididae crickets is their very long antennae, often several times the length of the insect, which they fold back over themselves.

There are several common names for these crickets, but most of the Australian ones are generally known as Raspy Crickets, due to the raspy sound they produce when they rub their abdomen against their legs, which they can use as a means of defence. Most of these crickets are apparently very habitat specific, but if you have ever taken the trouble to look closely at them, superficially they all look very much the same. So with that factor in mind and without microscopic examination, we appear to have at least two or three common species (one or maybe two large, and one much smaller) in the sandy heath habitat where most of my observations of these insects have taken place.

The single species above, or possibly 2 similar sized species are the larger of the local Raspy Crickets, having a head/body length of around 3 cm (11/4") and are regularly encountered during December and January, and again during April and May, leaving them noticeably absent during winter and the height of summer when they presumably remain in their shelters.

My thanks to Dr David Rentz for identification.