Auplopus architectus metallicus

A congeneric of A. mellipes mellipes, featured in an earlier post; unlike her cousin shown there, this pompilid is strikingly brilliant in her coloring, even to the naked eye. It’s harder to see that way, of course; this individual was about 3/4″ (18mm) from frons to abdominal apex. Luckily, I happened to be very near and already watching for movement when she turned up.

Despite their diminutive size, these wasps are exemplary in both strength and endurance. The spider she’s captured certainly outmasses her, perhaps by a factor of two, yet I watched her haul her prey up and then down the waist-high cyclone fence that borders my backyard. The above shot was taken while she dragged the spider along its top rail, the below while she was on her way there. Except to groom herself, she rarely paused.

Pompilid wasps, including those in the genus Auplopus, prey on spiders, but not for their own sake. The wasp’s venom paralyzes but does not kill the spider, which the mother wasp then buries with one of her own eggs laid upon or near it. When the egg hatches, the spider serves the wasp larva as a hapless larder, providing all the nutrition it requires to grow through pupation and into its adult form.

Even among the famously diverse family Hymenoptera, parasitoid wasps such as this one are enormously varied in their life histories and habits. Each genus and often each species has a unique design of burrow. Most are solitary, but some are quasisocial. Most provision each larva with a single spider and, once sealing a burrow, never revisit it; some practice progressive provisioning, bringing a series of smaller prey and providing the larva a degree of maternal care unusual in solitary wasps. Most are satisfied to simply envenom a spider or other item of prey; the tribe Ageniellini, of which Auplopus is a member, are unique in removing some or all of their envenomed prey’s legs for easier handling, as can also be seen here.

Horrifying? Perhaps – if you’re a spider. How might beef cattle regard humans?

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