For the love of spiders

Not everyone loves spiders, or even likes them. But spiders play important roles in many ecosystems, including home gardens and sometimes agricultural fields. This is mainly because they are excellent predators and eat many insects we consider pests. Spiders have a variety of hunting techniques that allow them to access many different types of prey. Some build webs and wait for their prey to come to them while others actively pursue their prey. Others are well camouflaged to their environment and wait for prey to walk within their range, these are called ambush predators.

Crab spiders, like the one below, are a good example of ambush predators. Crab spiders come in many different colors and hunt on different colored flowers, usually choosing one that lets them hide and wait for prey. IMG_1290

YouTube has some great videos of crab spiders catching other insects. Here is one of my favorites. The honey bees definitely don’t see it coming. Did you see the spider before it moved?

Sometimes they end up on the wrong color flower. Bad for hunting but good for taking pictures of them. This guy was really really tiny, about the size of an aphid.


In the pictures below I caught a crab spider on a flowering curly cup gum weed in my yard. The spider had just caught a male green bee (Agapostemon sp) and was devouring him.


Oddly, another male bee showed up right award and wanted to jump on the pile. I’m not really sure what was going on there.


There are over 3,000 known species of crab spider. One of them, the goldenrod crab spider (Misumena vatia), can actually change colors to match its background! They absorb and release pigments to best match their background. Some studies have shown that plants that have crab spiders on them sustain less damage from herbivores. Crab spiders also eat pollinators, however, which could be bad for the plants depending on pollinator abundance.

While eating bees and other insects, crab spiders have to be on the look out for predators of their own. Spider hunting wasps, birds, and my cats are all dangers for them. Given the numbers of spider hunting wasps I saw in my yard, I’m sure many turned into snacks!


Next week I’m going to over the oh-so-cute jumping spiders.




About keviclaire

I recently graduated from the Department of Environmental Science, Policy and Management at UC Berkeley. My research interests are focused on biological control and how to increase it's use in agriculture and home gardens. I am also an avid gardener and insect photographer. I'm using this blog as a place to share those interests!

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  1. No, the spiders will not eat all the people | Get Buggy - March 30, 2017

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