Monday, August 22, 2005

Catalpa worms


Poor little guys.

Almost every Catalpa worm (Ceratomia catalpae) on this tree had been parasitized by a Braconid wasp (Apanteles congregatus). The wasps lay eggs beneath the skin of the caterpillars, and the larvae feed on the them until they are ready to pupate. (The white cylinders are cocoons, not eggs.)

The wasps do the same thing to tomato and tobacco hornworms, amongst others, so are considered beneficial.

Poor little Catalpa worms, though.


Mightily encumbered.

More than you ever wanted to know about Catalpa worm anatomy is here.

28 comments:

KFarmer said...

I saw a BIG tomato worm the other day and it had those white things on its back. I wondered what they were. Thanks for the info.

the dharma bum said...

oooh, that doesn't look too pleasant.

Hick said...

Wow! I think I learn more on your website (and a couple of others that in which you have links) than I did in all my years of school. We've started up our homeschool year already and I'm using your site as part of my science curriculum. I think we need to go on a nature safari to see what we can find and identify. Thanks for the inspiration.

Rexroth's Daughter said...

It's always good to be reminded that nature isn't all pretty flowers and beautiful frogs!

pablo said...

Circle of life. Circle of life. I keep saying that.

swamp4me said...

It's beautifully efficient if you think about it.

thingfish23 said...

Here's a little more on that subject, if you'll indulge me a little.

That form of parasitism is even more remarkable when one considers that the braconid wasp larvae somehow know better than to "go for the jugular" on their host. Instead, they munch on the non-essential parts of the caterpillar first so as to keep it alive for longer.

Now, I ask you: How do they know to do that?

Anonymous said...

"Intelligent design"?

Floridacracker said...

To the tree, those wasps are a godsend. Be the tree...

Clare said...

Intelligent Design indeed. Those ancestor wasps when they started out down this route had two alternatives. Those that ate the essentials and didn't leave the host alive, didn't pass on their genes and didn't survive. Those that had mutated to snack on only the peripheral parts, which left the host alive longer, lived to pass on their genes.

Love your insect posts Rurality. I need more bugs in my life. We do, however, have a ultra cool Wooly Bear caterpillar that lives for 14 years before metamorphisis. Freezing solid each winter and carrying on where it left off each summer. How cool is that?

Magazine Man said...

As bad as I feel for those buggers, this was just the most fascinating thing I've read today.

Thomas said only two words, in exactly this order: "Gross! Cool!"

And you were worried about losing your audience of 6-year-old boys...

Rurality said...

Funky, huh? And icky, but interesting.

Hey wow Hick, thanks. How flattering!

Pablo, I need to see that movie. :)

Ooh, if you're going to try to start an "Intelligent Design vs Evolution" debate, you really should sign your name!

And really, this isn't the blog for that debate. Rurality has strong opinions but is a non-confrontational weenie. :)

Whoa Clare, a bug that freezes and thaws, huh? They do say that only bugs will survive in the end!

Oh MM I'm so glad I can keep the 6 year olds entertained, at least some of the time. :)

Ontario Wanderer said...

Some of us are over 60 and still enjoying and learning.

pablo said...

Maybe it's "malevolent design."

Rurality said...

OW you don't act a day over 11! :)

Pablo, don't get started... You really don't want me to have to say, "Now settle down" in my stern voice. :)

Karen said...

I guess that answers my question, "does this kill the caterpillar?" :(

Even though I hate creepy crawly things I feel tremendously bad for the caterpillars. Are they immobile while the cocoons are on them or can they still creep along, eat, etc?

L said...

sounds quite painful :o

Warren said...

so what does the braconid wasp look like???

PersimmonXing@aol.com

Dana said...

I awlays thought they were "catawba" worms. Now I know.

Rurality said...

Karen, they were continuing to move and eat leaves and such. But the ones with cocoons seemed smaller than the few who didn't have any.

Warren, here is a picture of one.

Dana, see here for earlier catawba/catalpa discussion!

A must-read poem. It's actually about a hornworm attacked by the wasps, but could equally apply to the catalpa worm. I really love this poem.

Anonymous said...

catalpa worms can be frozen and thawed and used for mainly catfish bait. if the worms are rinsed two or three times before freezing and then a small amount of suregell is placed in the water, they do not turn black in color and are actually a way better bait. suregell is a preservative used in making jam and jelly. try it. it works wonderfully.

Anonymous said...

i would sure like to know how the little catalpa worms get on the underside of the leaves.

Anonymous said...

You wouldn't say poor little worms if you got at least a million every year and they pooped all over your car!

food4thought said...

Clare, I agree, you can't get much more intelligent than a genetic design that is self advancing, in that it results in the most favorable outcome by passing on successful genes. What a wonderful tribute to its engineer. I would imagine that could be found in all life?

Bob said...

Up until about 15 years ago every year like clockwork the worms would show up in our county in Middle Tennesse. All of the sudden they stopped coming. They were great to fish with because the worm (if located next to a lake or river) would fall in the water making it almost a natural bait, especially for the redeye bass. What has happened to them. Is there a cycle?

Anonymous said...

ok so i've watched this gnarly old tree in my front yard go through this twice-yearly stripping for three cycles now and i finally HAD to google "catawba" worms. i'm glad sombody else finds this interesting.

thanks for the informative page, hey my son has a school project comming up, what a cool opportunity.

Anonymous said...

thats not cool!!!! ol dumb a** wasp

Anonymous said...

that is NOT KOOL at all!!! old dumba** wasp