Skip to content

I must admit I wasn't optimistic I would find much in our yard on January 3. It has been cold in the morning and insects aren't usually active when it's cold.

Wait. What's that tiny green thing?

It's a little praying mantis.

There's something in the brittlebush flower.

That's a crab spider with some prey.

What is this?

Although they look a bit like honey bees, these are flies. I didn't get a clear look, but probably flower flies in the family Syrphidae.

Not to shabby for a winter day.

We haven't had a spider lately for Bug of the Week.

crab-spider-face

How about a crab spider waiting for a meal?

crab-spider-on-purple-100

Crab spiders are known for using camouflage. In fact, adult female crab spiders have been shown to be able to change color to match the color of the flower they are sitting on.

So, why isn't this crab spider purple, or sitting on a white or yellow flower? Isn't being white going to wreck its chances of catching prey?

As this article from Wired points out, color matching does not necessarily help the spider to catch prey. One reason may be because bees can see ultraviolet light. Some spiders may reflect ultraviolet light, so even though the crab spiders look like they are matching the flower to our eyes, to the bees they stand out against their background.

This video suggests that standing out against the background may attract prey rather than dissuade it (it also shows crab spiders hunting).

Why would bees be attracted? The video does not explain this, but flowers have patches of ultraviolet that serve as beacons to the nectar. These patches are contrasting, and are thought to act like "signposts" directing the bees to the good stuff. Crab spiders may be trying to change the signs to direct flies and bees to themselves instead.

Now we are back to the question, why do female crab spiders change colors to match the flowers as we see them? Do you have any ideas?

What's on the underside of this ash leaf?

crab-spider-1

Although she's a few weeks early for Mother's Day, here's a diligent crab spider mom.

crab-spider-2

She's guarding her egg case.

crab-spider-3

She's been at it for two weeks now. Look how shriveled her abdomen is.

You go, mom crab spider!