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Pelecinid Wasps Laying Eggs

9-11-13 pelecinid wasp 211The two-inch, skinny, black, shiny wasps with extremely long abdomens (five times the length of their bodies) that have been appearing on lawns lately are not the villains you may think. These female Pelecinid Wasps (males are much smaller and rarely seen) are actually beneficial, in that they greatly decrease the June Bug population. That long abdomen, or ovipositor, cannot sting you – it is strictly a mechanism for laying eggs. Its length is due to the fact that the wasp inserts its ovipositor deep into the ground in order to locate beetle larvae — specifically, June Bug beetle larvae. The wasp then lays one egg on each host beetle larva, and when the egg hatches, the wasp larva burrows into the host as it feeds on it, thereby killing the June Bug beetle larva. Eventually the wasp larva pupates and emerges above ground as an adult wasp the following summer – the phenomenon we are currently witnessing.

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9 responses

  1. Marilyn

    Isn’t nature clever!

    September 11, 2013 at 11:41 am

  2. Interesting!

    September 11, 2013 at 12:26 pm

  3. dellwvt

    I remember looking up these wasps many years ago when my students and I were alarmed to come upon them during our fall nature observations, but as usual, I’ve learned more, reading your offering this morning. Thanks once again!

    September 11, 2013 at 1:08 pm

  4. karenshaunmurphy

    Mary, I am wondering if this wasp also lays her eggs in the japanese beetle grubs? Karen Murphy

    September 11, 2013 at 1:31 pm

    • What a great question, Karen. I don’t know for sure, but I would presume so, as this wasp preys on beetles in the family Scarabaeidae, of which the Japanese beetle is also a member (along with June bugs).

      September 11, 2013 at 2:19 pm

  5. Al Stoops, Nelson NH

    I’ve always called these “ichneuman” wasps, as my little yellow golden guide from my childhood featured them, and they look very similar.

    September 11, 2013 at 4:32 pm

    • Ichneumon wasps and Pelecinid wasps are both parasitoids, and both in the Hymenoptera order, but in different families. I, too, grew up calling these ichneumon wasps!

      September 11, 2013 at 6:33 pm

  6. Al Stoops, Nelson NH

    …a quick online search found this discussion. I wondered if they were the same things (I misspelled ‘ichneumon’ in my previous comment), apparently they are not.

    September 11, 2013 at 4:36 pm

  7. Nature’s own natural pest control device!

    September 12, 2013 at 11:23 am

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