Question of the day

It could be the rear of a stick insect with an egg emerging. The egg has a knob on it that ants like to eat, so they take it back to their nest. They just eat the knob though, so the egg will remain intact in a safe place and hatch later.

That's exactly what it is.

Nice piccie Alex! Am hatching some Extatosoma tiaratum as I type. Can't wait for these little fake Leptomyrmex's to be running around our place.

What species is this photo of? What lovely black eggs.

Ten more points if you can name that knob.

Damn PaulM beat me to it -- but it is worth noting that the walking sticks are probably basically hijacking the ant/plant elaiosome symbiosis to their own ends. Pretty amazing stuff...

No 10 points for me but, hey, I learned something new.

The little nob is the operculum. (I looked it up only to make sure I was right before I posted, I promise :)

Does anyone know why phasmatodea eggs are less likely to be eaten? Is that even true?

In addition, the eggs that are "harvested" by the ants receive protection from egg parasites. Ants that eat the fat-rich "elaiosome" are probably not interested in the "seeds" per se. Thus they become effective seed dispersers because they're not seed predators.

Wow, you guys are great! That was both fast and accurate. The stick insect is Diapheromera femorata, a common species in eastern North America.

Let's see. 20 points to PaulM. Another 10 to scitso. And an extra 5 points to everyone else for the additional info and anecdotes!

Now. 10 more points to anyone who can figure out what the points are good for, anyway.

Why don't the ants eat the insect when it hatches? They eat other insects.

Woo! Points for me! Not bad for my first post on this site.

Erik: I'm certainly no insect specialist (I'm an I.T. peon with an amateur passion for everything zoological) but I'm sure I've read somewhere that some stick insect nymphs can mimic ants, so that might be how they avoid being eaten. I don't know if Diapheromera femorata is one of those though.

My source on this is "Life in the Undergrowth" (the movie), so I'm not sure, but it seems they avoid being eaten by running like hell up the nearest tree. I doubt they all manage to get away.

PaulM- I'm not sure how effective mimicry would be unless they smell like their "host" ant. And if they do smell like them, they don't necessarily have to look like them. Ants don't really care what you look like (usually), it depends on what you smell like.

Scitso: "Life In The Undergrowth" is how I was able to initially identify the photo in this post. I've got all of Attenborough's shows on DVD. Highly recommended for zoological laypersons like me.

Some poking around online shows that Extatosoma tiaratum mimics ants when hatched, but I cannot find any clarification on whether or not the mimicry is to fool the ants in the nest or other predators while it heads to the trees.

Is there anyone here who actually has some genuine knowledge on the subject?

Well, we could always ask Kirsti (comment #2), as she seems familiar with Extatosoma.