The tastiest part of a cockroach is its heart

I did not know this. Being a giant relative to cockroaches, I’d only imagined mashing the whole animal into a pulpy mass between my molars, but apparently, with a lesser size difference, one can be a connoisseur of the flavors of different meats in the prey animal, and appreciate the subtleties of the meal. As the emerald jewel wasp does.

And so, in another attempt to win his students’ attention, the scientist set out to film an emerald jewel wasp larva as it feasted on the cockroach from within.

“That’s the way science often unfolds for me,” said Dr. Catania, the author of “Great Adaptations.” “I’m looking at something out of curiosity, or art.”

This is how he ended up capturing the larva’s taste for cockroach heart. But he made an unexpected discovery: After eating the heart of the cockroach, the wasp larva started gnawing at its quarry’s trachea, the insect equivalent of lungs. This caused air to leak out of the cockroach’s respiratory system and into its body cavity, air that the wasp larva then eagerly slurped up.

In other words, the emerald jewel wasp both eats the cockroach’s heart out and takes its breath away.

After performing the experiment two dozen times, Dr. Catania was able to show that not only do the air bubbles allow the larva to breathe while fully inside the cockroach’s body, but they also give the little hell-raiser a metabolic boost. Once the air bubbles appear, the larvae start to chew faster, which Dr. Catania documented this year in a study published in the journal Current Biology.

Now that’s an interesting twist. When you’re head first in the gooey, slimy, liquid interior of the victim you’re eating, respiration becomes a problem — so you suck air out of its respiratory system. Brilliant! I’ll remember that next time I dive into the body of an animal 50 times my size.

There’s a video if you’d like to see a living cockroach heart get eaten by a wasp. It’s cute and heartwarming.


  1. Akira MacKenzie says

    @ 2


    ASH: You still don’t understand what you’re dealing with, do you? A perfect organism. Its structural perfection is matched only by its hostility.

    LAMBERT: You admire it…

    ASH: I admire its purity. A survivor. Unclouded by conscience, remorse, or delusions of morality…

    Well, the cockroach didn’t stand a chance, but it “has my sympathies.”

  2. robro says

    “Now that’s interesting twist” — Hmmm, you might say you took my breath away with that one, PZ.

  3. birgerjohansson says

    The cockroaches need to gang up on cockroach Ash and kill him. And then burn out the infestation with flamethrowers.

  4. ealloc says

    I gotta admit, he successfully got me hooked with his cliffhanger at the end of the video. Now I’m looking forward to more cockroach parasitoid videos in order to learn why the wasp would have selection for fast eating!

  5. wzrd1 says

    Cockroach: Have a heart!
    Wasp larva: Don’t mind if I do.
    Cockroach: awshit…

    Where is the tracheal opening(s) on a wasp larva? Can’t seem to easily find any anatomical diagrams for their larvae.

  6. says

    PZ wrote: There’s a video if you’d like to see a living cockroach heart get eaten by a wasp. It’s cute and heartwarming.
    I can’t help but wonder if that is a metaphor for the way Rtwingnut Xtian Terrorists are murdering (what’s left of) our government and society. But, unlike PZ’s insects, the Rtwingnut Xtian Terrorists devouring our society are not “cute and heartwarming”

    @7 birgerjohansson wrote: I found even worse parasites: health insurance scammers
    I reply: you are absolutely correct! Medicare Advantage Insurance Corps have swindled taxpayer money out ot gov’t Medicare by 240 BILLION usd (figure remembered from reading the article last week, need to verify it). The term Medicare Advantage is a fraud. When you sign up, they rip you out of the gov’t Medicare program, so when they deny your live saving medical care, you have NO RECOURSE.

  7. StevoR says

    I’ll remember that next time I dive into the body of an animal 50 times my size.

    – PZ

    Next time?

    What happened the last time and how often exactly do you end up in that particular sticky situation, I wonder?

    Come to think of it is even a Blue Whale literally 50 times larger than we are?

    (Cue really nasty twist on the story of Jonah..)

  8. Silentbob says

    @ 14 StevoR

    If size means volume, for which we can roughly substitute mass, that’s only about 4 tonnes. An elephant would qualify.

    A quick goog shows a blue whale to be about 140 tonnes. X-D

  9. wzrd1 says

    A quick goog shows a blue whale to be about 140 tonnes.

    So, roughly around my apparent mass when I get up in the morning.
    Well, at least it feels that way.

    Repeal gravity, an unfair and oppressive laaaaaaaawwwwwwwwww… Oops.

  10. wzrd1 says

    Silentbob, do Goog a blue whale’s scrotal contents quantity. Dunno if I want to ponder ovarian quantities.
    One of the sparse few animals that likely could tow an aircraft carrier, should they be so inclined.