Mammoth Wasp from Portugal

Subject: Scoliid wasp?
Location: Salir, Algarve, Portugal
July 28, 2016 9:56 am
I spotted this huge specimen in my garden in the Algarve, Portugal. It was quite docile and tried to hide underneath my shower decking. It was about 5-6 cm in size and as you can see from the picture is black with four almost square yellow panels on the lower half. My Portuguese friends are saying it’s a bee killer, is this true? I’ve done some image searches and it looks like a Scoliid wasp, although I’m not sure those are native to Southern Europe. Thanks for your help.
Signature: Vincent

Mammoth Wasp
Mammoth Wasp

Dear Vincent,
You are correct that this is a Scoliid Wasp or Mammoth Wasp, most likely
Megascolia maculata AKA Scolia maculata based on this FlickR image.  It is also pictured on iNaturalist.  Your friends are wrong.  Scoliid Wasps do not prey upon bees.  Adults take pollen and nectar from flowers like most wasps, and the female hunts for Scarab Beetle larvae.  Project Noah indicates there are three subspecies and provides this information:  “The larger female (may reach 5.5-6 cm) can be told apart by her yellow head and short antennae. The male has a black head and longer antennae. Both have two yellow bands on their abdomens, which can be divided to form 4 spots as it is shown on the photos. Nevertheless, they hold no harm to humans despite their size, in contrast to common wasps and hornets. Indeed, mammoth wasps do have stings, but not for self-defence or nest protection (in fact, they are solitary wasps). You may see several of these wasps flying around decaying tree stumps, they have a purpose there. They’re searching for larvae of Rhinoceros beetle (lat. Oryctes nasicornis), The female wasp once she has discovered the huge larvae, will sting one to paralyze it and then lay her egg on the outer skin. After hatching, the larvae of the mammoth wasp starts eating its host, till reaches the size it could create a cocoon, where it can safely sleep through all winter. 6 months later, the larvae turns into pupa and after 1 month more, from under the underground emerges newly formed mammoth wasp. The adult once feed on flower nectar.” 

Thank you very much for clearing this up! I’m also happy to hear they feed on the rhinoceros beetle, those were responsible for killing the magnificent palm tree we had in our garden a few years back. I’ll definitely not harm these wasps when I see one in the future. Not that I would harm any creature, great or small 🙂

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