Sunday, February 11, 2007

Helea and a Sympetes species from the SE of WA

Pie-dish Beetles are not only very unusual, but can be steaming hot too!

The genera Helea, Pterohelaeus and Sympetes (commonly known as Pie-dish Beetles), are endemic to Australia (Sympetes only in WA) and belong to the family Tenebrionidae. There are over 50 species and although widespread, they tend to favour the drier regions. The Helea species are distinguished from Pterohelaeus and Sympetes by having a wider flange with the top section meeting or overlapping above the head.

A very hairy backed Helea perforata from the Esperance region of WA.

All Helea and some Pterohelaeus and Sympetes beetles are wingless and their elytra (hardened forewings that form the back of the beetle) are fused together. As their breathing system is below the elytra, a micro environment is created to retain moisture and enable easier breathing, both an advantage in a dry climate. Anyway, they are nocturnal and ground dwelling, but by day usually rest under leaf-litter, rocks, logs or loose bark. They will often return to the same resting-place each day.

The hardened elytra and flange provide protection from predators, as they can resist penetration from spider fangs or scorpion stingers. They can also use the flange to flatten themselves on the ground to avoid being turned over or attacked from below.

A mating hairy-backed couple not bothered by extended flanges. Note how the flanges overlap above the head.

Pie-dish Beetles, Helea perforata

Most of the Esperance pie-dish beetles are between 1.5 - 2 cm in length and are not hairy; in fact some are quite smooth and shiny like Sympetes testudineus, although the one photographed below could be the same as the mealy species further down, but older with the flour-like substance eroded away.

The Sympetes pie-dish beetle below is having a nibble on a rolled oat, it has a covering of fine flour-like grains on the elytra, but take note of the missing flange section above the head, this is the most obvious distinguishing feature between it and the Helea pie-dish beetles.

The single raised portion along the back, is common to these beetles (all genera), being the fused portion of the elytra, however others can have additional ribs on either side.
Pie-dish Beetle, Sympetes species

The oat munching Sympetes Pie-dish Beetle in profile. Note there is very little for any predator to grasp. However all adult pie-dish beetles are very inoffensive, being vegetarian and normally only feeding on dead and decaying plant material.

Note with this mating pair of Helea consularis (flange meeting above the head) the additional ribs and their pronounced raised flange. These flanges are not raised to enable mating but are a feature of this species.

I stopped filming after this shot as I was beginning to suspect that I was becoming involved in a hot pie-dish porno movie.

So next time you spot a pie-dish beetle wondering around at night, check out its features to see how many types you have. You might be surprised!

Updated March 2013. 


huntervalley said...

Fascinating creatures, Jack!

I have only found one species of Pterohelaeus in my garden, and I was amazed at the almost comical-looking beetle when I first spotted one. I've seen several since.

Some of yours have an almost prehistoric look to them. And you've done exceptionally well to capture the mating shots.

Being in a relatively dry climate, do you know if they get enough moisture from the food they consume, or do they need to actively seek water?

An extremely interesting blog entry.


Esperance Blog said...

Hi Huntervalley, they sure are interesting beetles, I've been following them around for quite a while now. The good thing is they are easy to find and don't run away. :)

I think they get their moisture from plant material and rain/mist/dew. They are very adaptive to dry conditions so probably don't need much.

Recently I had a couple of bird baths on the ground and some of these beetles were attracted to the water, fell in and drowned. :( So like many dry-land animals, although they can make do with very little, if available they will not hesitate to partake.


Gaye from the Hunter said...

hi Jack,

I note that you say pie-dish beetles eat mainly dead and decaying plant matter. Do you know if, or have you seen, pie-dish beetles eating lichen? I have observed them lately on lichen-encrusted rocks in my fern garden at night.



Esperance Blog said...

Hi Gaye, I can't answer your question with any certainty, as I have not observed or heard of them feeding on lichen before. As I said they mainly feed on dead and decaying matter and so possibly could include other things in their diet too. It may even be the pie-dish beetle cleaning up dead and damaged material on the lichen and so might be of benefit to it. I would be interested to hear of any sightings you make in this regards.


Anonymous said...

We have found one of these beetles in Venus Bay on the Eyre Peninsula in South Australia....maybe he hitched a ride in a caravan. It was snooth & black