Sunday, 21 April 2013

You Wouldn't Want to be a Spider - Spider Hunting Wasps

Spiders and snakes are probably the most maligned groups of species. Spiders are renowned for catching eating unsuspecting prey but spiders too are under attack.

There is a group of wasps specifically known as Spider Hunting Wasps. They comprise the family Pompilidae and this week I've spotted or named two species from Riddells Creek and another from Daly Reserve in Gisborne. They are quite noticeable by their behaviour - they fly just above the ground scanning an area for spiders, landing occasionally but forever on the move.

A few weeks ago I spotted a Zebra Spider Hunter Wasp at Daly Reserve and this species I finally spotted in Riddells Creek last week (a new species record for Riddells Creek). I managed to key it out via a 1984 paper from the Australian Journal of Zoology as Turneromyia bassiana and this ID was later confirmed by Ken Walker (Head of Entomology at the Museum),

As mentioned, this species was also spotted at Daly Reserve, Gisborne, where more details of its behaviour was observed. The pic below was taken while it 'tapped' on the stick across the small hole in the ground. It is assumed this is its den since we later saw another individual digging a similar hole. The dirt from the diggings is seen right of the picture below,

The above species inspired my daughter, Lydia (10), to draw the lesser known 'Zebra Spider Hunter Elephant' ...

I've only seen the Zebra Spider Hunter Wasp in forested areas (with grass-dominated understorey) but the next species I've only seen (but regularly see) on Riddells Creek's grasslands. It is easily seen because it is very brightly coloured. It is Cryptocheilus bicolor (Orange Spider Wasp). It is also very difficult to photograph because it is very flighty and keeps a good distance (from me anyway). The individual pictured below is pulling a spider into a large crack in the drying basalt clay,

The spider wasp below is commonly seen but more commonly heard at my house. It is a hyperactive wasp and forever building mud nests all around the house, especially buzzing away in the grooves of our fly-wire security doors. I accidentally knocked off a nest once and found it contained more than a dozen small spiders. I have only worked it out to genus level, Fabriogenia spp., 
... and this dead one spotted by my daughter Ellena,

At Daly Reserve, in the same area covered by the Zebra, I also spotted a much smaller spider wasp which turned out to be Psoropempula erythrostethus (ID by Ken Walker), I haven't spotted this species in Riddells Creek (yet):

But it doesn't stop there for the poor old spiders ... on the same day I spotted the Zebra in Riddells Creek, I also spotted this species exhibiting the same hovering/scouting close to the ground behaviour that is a feature of spider hunter wasps:
I initially thought this was also a Spider Wasp but close inspection of the photo shows the large spike emanating from the rear. This looks like a horrific stinger but is actually an ovipositor (used for egg-laying). This is a feature of Ichneumon Wasps (family Ichneumonidae). It was named to species level by Ken Walker as Tryonocryptus gigas, I suspect this species might be a spider hunter too. Ichneumon Wasps lay eggs in the host using the ovipositor. I also spotted this species at Daly Reserve within just a few metres of the two spider wasps.

So next time you see a spider, you may view it with a little more sympathy (or maybe not). Humans aren't the only ones giving them a hard time.

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