Monday, August 30, 2010

Ambush Bug

I have a spearmint plant that is currently flowering. The massive profusion of flowers attract a wide variety of pollinators including wasps, butterflies, bees, hoverflies, beetles, and even hummingbirds. I stepped out of the house the other day and was delighted to see a painted lady butterfly flapping in the wind as she fed from the flowers. As I got closer, though, I noticed that not only were her feet not touching the flower, they weren’t even moving. The butterfly seemed to have gotten her head stuck in the flower and died. Naturally, I took a closer look. What I saw was a small insect holding on to the head of the butterfly and feeding on it. The insect looked so much like the flower it sat on that it was difficult to see, even though I knew where to look and what to look for. What particularly impressed me was the size of the insect. Its body length was less than a third the body length of the butterfly and overall mass was probably a fifth or less that of the butterfly. Despite the saddening loss of a butterfly, I still found the whole spectacle fascinating.

The next step was to identify the predator. My first thought was that it was an assassin bug. Assassin bugs are very effective predators that I would be proud to have in my garden. They lie in wait, often with excellent camouflage. Lacking jaws, they stab their prey with sucking mouthparts, quickly killing them and then sucking out the innards. They are nearly as voracious as the more famous ladybugs and praying mantis, but smaller (usually) and harder to spot. Nonetheless, they are exceptionally beneficial for the garden. However, upon doing a little research, I found that the blocky head and praying-mantis-like grasping forelegs of my little guy didn’t fit the description of an assassin bug. A little more research showed it to be a close relative of assassin bugs, an ambush bug. Just like their cousins, ambush bugs are voracious predators that lie in wait, often on flowers, to grab passing prey. The article I found said that they can routinely handle prey ten times their own size. That’s about like a house cat taking down and killing a small wild pig.

Once I knew what I was looking for, I looked around for more and quickly found 6 or 7 more hiding among the flowers. I also found some eggs laid on the branches that I can only hope are ambush bug eggs. I must say that I will keep an eye out for these guys in the future. Maybe it is their fault that I have had little to no pest problems this summer. Or maybe it is the fault of the one praying mantis I have seen lurking about. It is probably a combination. Either way, they are a treasure.

Photos courtesy Jenny Williams


  1. Thanks for the interesting post - can you tell us which part of the country this was in?

  2. I live in Northern Arizona and took the picture in my back yard.