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Predator wasps are helpful, not harmful

          20190810 Valk Valley Pelecinid Wasp HawkeBy David Hawke -- There are wasps... and then there are other wasps.

There are so many wasp species that collectively they make up one of the largest groups of insects in North America. A few of them we know quite well, our initial acquaintance oft from a painful interaction between their rear-end stinger and our sensitive nervous system. Is there a difference between a wasp and a hornet? When you've just been nailed by one on the tender backside of your leg, the last thing you wish to discuss is whether or not it was a wasp with an attitude or a hornet with a nest to defend! "Somebody, just kill the damn thing!!"

          But there are other wasps, many other wasps, that have little or even no intention for doing us harm. Within this group of 'other wasps' is a cluster of those which go by the label of predator wasps, who despite their name do not consider us worthy or appropriate of their time. Their survival depends upon finding a succulent caterpillar or grub to host their babies.

          Predator wasps do not build a nest or even a colony. Other than finding a mate they are solitary and will even forgo eating during their quest to find a home for their eggs. These are the ichneumon (ICK-knee-ew-mon) wasps, and they are gathering in your yard even as we speak. Crawling over tree trunks, they are pausing, laying their antenna lightly on the bark, trying to pick up the tremor of a wood boring grub.

          Ichneumon wasps (are there are a lot of different ones) all generally have long antennae and a very long abdomen, often two or three times the length of their thorax. You can't miss them -- they are one strange looking insect.

          Now, if you are a fan of science fiction, your imagination will take you to the conclusion that a rear-end stinger that long must be used for very diabolical reasons. Wrong-o. It's more an egg transfer device than a defensive (or even offensive) weapon. But gotta admit the thing do look gangsta!

          So, if not for penetrating deep within my leg muscles, why the long tail piece? Being a predator wasp, it needs prey, not for eating but to act as a nursery and buffet for its soon-to-be-laid eggs. Okay, science-fiction fans... go deep with this...

          Once a wood-boring grub is detected munching its merry way through some somewhat decaying wood, the ichneumon wasp drives its tailpiece into the wood, penetrating through the cellulose fibers until contact is made with the grub below. The tail end is inserted into the grub and an egg is laid inside the tunnel maker. When the egg hatches it will eat the grub from the inside out (okay, does that put the "ick" in ichneumon or what?).

          By the time the grub is dead the baby ichneumon wasp is now in its own pupae stage of development. When it emerges as an adult, it will use the tunnels made by its host to escape back to the outside world.

          No doubt you can see the immediate benefit to humankind (besides being fodder for the theme of a creepy movie). All those hidden wood boring grubs would soon destroy a woodlot if left unchecked, and these predator wasps are ensuring a cap is kept on the prey population. Interestingly, each species of ichneumon wasp has a very specific prey species upon which to lay its eggs.

          That long 'stinger' does not have the strength to penetrate our skin, nor does it want to. But soft wood with minute cracks within, now that is where these devices shine!

          I clearly remember my first encounter with such a beast (and yes I'm going to tell you, whether you care or not)... I was coming home from school (Mount Slaven, in Orillia) for lunch break, wandering up Mackenzie Street between John and Nottawasaga Streets. There is (or was) a black walnut about halfway up this block (west side), and I noticed this beautiful long-tailed insect on the walnut trunk. Being about eight years old and not yet aware that bare hands are not always the best way to handle large insects, I scooped it up and carried it cupped between my palms the rest of the way home.

          Once home, which was just around the corner, I knew I had to let it go so that I could scoot inside to get a big jar to keep it in. The wasp was placed on the side of a fairly young (at that time) Crimson King maple tree whilst I went in search for said jar. Alas, when I came back, the wasp was gone. But the memory was captured.

          There have been several of these gorgeous black-tailed insects noted over the past week throughout our region, so take your time, walk with eyes open, and you may just find the next inspiration for a block-buster movie simply sitting on a half-rotted log.

David’s notebook: The picture does not quite match the story, and that's okay... next week's blog will address that mistaken identity in a fun way.

© 2019 David J. Hawke

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Senior lady with a heart of gold
Update: ADOPTED! :-) Sassy will be your furry budd...
 

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Wednesday, 20 November 2019

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