The fir needle moved …

fir needle insectI was on a hike near Whistler in south western British Columbia, where I was about to brush what I thought was a fir needle. It was slowly moving across my hand. Is this a type of stick insect or assassin bug? I did notice a possible straight proboscis (about one fifth body length) on the underside.

It moved quite slowly for a predatory insect … ~4mm per second. I didn’t want to aggravate it too much and put it down on some fir needle-covered moss.   Peter

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One thought on “The fir needle moved …”

  1. puffin    Hi Peter, thanks for writing. I was not sure what that was either, but the people at quickly identified it as a “stilt bug” in the family Berytidae.

    Stilt bugs are “true bugs” in the order Hemiptera, as evidenced by the proboscis you noticed. Some of the stilt bugs both suck plant juices and also prey on other insect eggs, larvae, and adults. When I searched for Berytidae in British Columbia I found the page linked below, which shows two species that look very close to your crawler, Jalysus wickhami and Neoneides muticus. I’m not an expert in these insects, but based on what seems like a slight “waist” in your photo, I think it’s Jalysus wickhami. Apparently, even experts can mistake J. wickhami and the nearly identical J. spinosus, so it could be either one of those species. Both are found all over North and Central America.

    J. wickhami uses its proboscis to feed on plant sap, but it also uses that same piercer to puncture eggs of other insects. In fact, it performs what is called “intraguild predation,” meaning that it preys on some of its own competitors. In a 90-day adult lifetime, a Jalysus stilt bug might eat 2,000 eggs of other insects like aphids. This makes them an interesting, but tricky-to-use, method of agricultural insect control. If you want to control aphids, you might want to introduce stilt bugs, and accept that the stilt bugs will suck some plant fluids, but by killing hundreds of aphid eggs, their overall effect will be positive. Also, if you use insecticides to kill aphids or other insects, you might very well kill the stilt bugs, making them unavailable to eat aphid eggs. Tom

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