Tiny Wasp Hero Slays Redback Spiders in Australia

Spider wasps in the family Pompilidae are fearless hunters of arachnids as small as jumping spiders and as large as tarantulas (the "tarantula hawk" wasps), but I was unfamiliar with any species of pompilid going after cobweb weavers in the family Theridiidae. That was until late last week when these stunning images came across my Facebook news feed.

Abel González snapped these images of a female Agenioideus nigricornis spider wasp carting a paralyzed Redback Spider, Latrodectus hasselti, back to a nest burrow in Oldbury, Western Australia. The significance of this behavior requires a bit of backstory.

The Redback Spider is one of the most dangerously venomous arachnids in Australia. Indeed, it is in the same genus as the widow spiders of North America: Latrodectus. Any organism that targets such a potentially lethal animal deserves some acclaim. Oddly, we have species of the wasp genus Agenioideus here in the U.S. as well. I witnessed a female A. humilis hauling a comatose orb weaver here in Colorado Springs last year, and even posted about it, complete with video, in this blog entry. Our New World species do not go after cobweb weavers, let alone widows.

The initial discovery of the relationship between the Australian A. nigricornis and the Redback Spider is credited to a nine year-old boy, who spotted a wasp dragging a spider in his backyard in Beaconsfield, Western Australia. The young lad pointed out the drama to his father, who was astute enough to collect the two animals and photograph the habitat. The specimens eventually crossed the desk of Andy Austin, a professor at the University of Adelaide, who identified them.

This is not a big wasp. Females are only 8.24-13.11 millimeters in body length. Perhaps their diminutive size helps them navigate the labyrinth that is a Redback Spider's web. It is apparently still a mystery how the wasp manages to subdue its prey to begin with.

Back here in the U.S., the only spider wasp thought to be a potential predator of widows is Tastiotenia festiva, based on one circumstantial record from Rodeo, New Mexico. The range of T. festiva is restricted to the extreme southwestern U.S. One other wasp is very well known as a predator of widows. It is the Blue Mud Dauber, Chalybion californicum, a very widespread member of the family Sphecidae.

The Australian wasp was known to science as far back as 1775, when it was first described from specimens collected by Captain James Cook in 1768; and it is a common insect found throughout Australia. The fact that its host was unknown until the 21st century speaks to how much we have yet to learn about even the most familiar of invertebrates.

Sources: Krogmann, Lars, and Andrew D. Austin. 2012. "Systematics of Australian Agenioideus Ashmead (Hymenoptera: Pompilidae) with the first record of a spider wasp parasitizing Latrodectus hasselti Thorell (redback spider)," J. Aust. Entomol. Soc. 51: 166-174.
Staff. 2012. "Killer Spider Meets Its Match in Tiny Wasp," LiveScience.
Wasbauer, M.S. and L.S. Kimsey. 1985. "California Spider Wasps of the Subfamily Pompilinae," Bulletin of the California Insect Survey. Vol. 26: 1-130.

That Viral Video of the Giant Moth

There is currently a video of a giant moth that has gone viral, with a complement of completely incorrect identifications. This blog post will help sort fact from fiction and address the problems that stem from "oversharing" of such posts.

Here is the video, which elicits the full spectrum of human reactions from horror to beauty to fascination.

Giant moth

A truly horrible – and GIANT – moth.

Posted by The Daily Star on Tuesday, September 15, 2015

At first glance, the creature strongly resembles a sphinx moth. Indeed, given the location of Australia, many have identified it as the Privet Hawk Moth, Psilogramma menephron. The moth in the video is even larger, though, and the head and legs look a bit different.

It took a little bit of "Googling" myself to find the real answer. Turns out this is a "Giant Wood Moth," Endoxyla cinereus. Most people are not familiar with the carpenter moths of the family Cossidae, to which this herculean lepidopteran belongs, so it is no surprise that the moth in the video has been repeatedly misidentified.

This moth was formerly known as Xyleutes cinereus, which might add to the confusion. The caterpillars are grubs that bore in solid wood of eucalyptus trees. The adult female moth can have a wingspan of up to 23 centimeters; and it is the world's heaviest moth, weighing in at up to 30 grams.

Videos tend to command our attention, and we often forget to read the introductory material to learn where the subject was recorded, and other relevant information. Sometimes, the person posting the video fails to include those important details, too. Consequently, viewers may post comments that are not applicable. Before you know it, not only is the video going viral, but so is all the misinformation.

The speed with which erroneous "facts" are broadcast, often unwittingly, is at an all-time high thanks to the internet, so it is up to us as scientists and journalists to do the best we can to correct them, as quickly as we can. I urge you to use your own blogs, Facebook posts, Twitter, and other social media to do just that.