Can you identify the species of insect from the larva in these pics

Asked October 18, 2018, 11:58 AM EDT

This summer I left my leaf cutter bee block on my deck, since I was not planning on deploying it in my garden along with my mason bee block. To my surprise, by the end the summer several holes were plugged with mud in the leaf cutter block. Now that I am harvesting cocoons from my mason bee block, I was planning on harvesting what I expected would be mason bees from my leaf cutter block. To my surprise, instead of cocoons, I found relatively large yellow larva with ribbed bodies. I have attached pics of the larva in the hopes you can identify them and let me know if I should by trying preserve them as beneficial insects, or dispose of them as pests?

Oakland County Michigan

1 Response

All I can tell from the pictures is that these are a Hymenopteran of some sort... either a bee or a wasp larva. We really can't tell until the adults emerge, although a close examination of the pupal stage might tell if they are wasps or bees. If they are bees, they could be a mason bee species; if wasps, there are several possible groups that use existing cavities and mud to form cells, just like bees. All of the wasps that do this are predatory.