Thursday, June 21, 2012

Ground Cherry Leaf Beetles

There are several species of Ground Cherries, genus Physalis, growing at Blue Jay Barrens.  I’ve been watching a few specimens with plans of photographing each when it reached its prime.  All are very similar, with most differences being associated with leaf shape and the degree of hairiness.  Yellow, bell like flowers are typical of all.

The fruit develops inside a thin walled pod.  It’s not uncommon to have flowers and nearly mature fruit on the same plant and that’s the condition I’ve been watching for.

My latest check showed flowers and developing fruit, but most of the leaves and some of the flower buds had disappeared.  This wasn’t the scene I had been hoping for.

It wasn’t hard to discover the cause of the leaf loss.  Beetle larvae were hard at work eating everything except the stout stem.  The larva is that of a leaf beetle and looks very much like that of a Three-lined Potato Beetle.  Several species have larvae of similar appearance, so it’s hard to be positive at this stage.  The interesting thing about this guy is the bit of protective camouflage it carries on its back.

A chain created from the larva’s feces runs up the back and almost to the head of the tiny creature.  The mass of feces definitely makes the larva less visible and may even make the larva less palatable.  It’s also possible that a grabbing type predator may come away with a bunch of feces instead of a larva.  However it works, there must be some survival advantage for this behavior to have developed.

The size of the feces mass varies between individual larvae.  It seems that the feces could be easily dislodged, but there is some type of projection in the center of the back that appears to act as an anchorage for the feces chain.  The larvae made for an interesting diversion, but all of those feces nuggets were once the leaves I was hoping to photograph.  I guess I’ll have to look around for some more plants.

7 comments:

  1. Very interesting I can envision a science fiction movie with the bad guy being a creature like the beetle with the feces on its back:)

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  2. Hi Mona. I'm sure it would make a very convincing movie monster.

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  3. I propose the chain of feces running up its back looks like a bird turd. This acts like camouflage...a predator may think it's seeing a bird turd rather than a potential food item.

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  4. Hi Mark. That's certainly a possibility.

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  5. It's amazing.. it looks horrible !
    This's happening to one of ma Datura.. I'm going to look for these monsters. Thanks..
    chatou

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  6. Hi Chatou. I hope your Datura survives the attack.

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  7. Three-lined Potato Beetle larvae - Lema daturaphila

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