August 2023 Natural Mystery Answered

Last month’s natural mystery really showcased the depth and breadth of knowledge in our community. Six of you identified this tiny animal to species and wrote detailed descriptions of your process. Congratulations to Mike Holtz, Alan Holzer, Bill Kass, Bonnie Ploger, Carol Stiteler, and Eric Vehe. I will do my best to pass along some of the insights, details and resources that you all shared in answering this mystery.

This is a Northern Crab Spider (Mecaphesa asperata).

Alan starts us off by noting the characteristics that help us recognize this critter as a spider: “two sets of legs are being held out to the side, and two are holding on to the leaf. This animal has only two main body parts (abdomen and cephalothorax) as opposed to three for insects.” Bonnie also notes that this critter has 8 eyes, which is also distinctly characteristic of spiders.

Alan, Bill, Bonnie & Mike all note that the posture helps us distinguish this as a crab spider (Thomisidae family). Mike cites the University of Minnesota Extension website: “The first four legs are longer than the back four and are held out to the sides giving a crab-like appearance.” Alan also shares that crab spiders “often sit on or near flowers, blending in, and waiting to capture prey that visit the flower.” I’m sure Bill speaks for many people when he writes, “I like to call them flower spiders because that is where I usually find them, on my flowers at my house.”

People used a range of resources to identify this crab spider to species. Bonnie began by doing an image search using keywords “green crag spiders Minnesota,” and comparing color and markings. This led her to MinnesotaSeasons.com and then to Bugguide.net and Arachnids of North Carolina. Mike also went to MinnesotaSeasons.com while Alan turned to Spiders of the North Woods by Larry Webber to narrow down the ID.

In identifying the species, Eric shares:

“This Northern Crab Spider is common in Minnesota and the second most commonly reported species of crab spider in MN on iNaturalist. The carapace (the visible side of the cephalothorax or the head/thorax region) is documented as brownish or brownish-yellow to pale green (very green in this individual) with two stripes varying from pink to reddish-brown running the length of it. The abdomen is typically some shade of yellow, off-white, or green with prominent brown to red marking.”

Bonnie cites Bugguide.net as saying:

“key characteristics are the broad stripes on cephalothorax (prosoma), wide anterior patch on abdomen and broad, jagged confluent maculae (the big stripes) on abdomen (opisthosoma). Bugguide also says there is a triangle or T between the anterior patch and maculae. In the photo, two dark spots are somewhat triangular, when zooming.”

Mike shares these characteristics with us from MinnesotaSeasons.com:

“In the front row the outermost eyes, the anterior lateral eyes (ALE), are a little larger than the interior eyes, the anterior median eyes (AME). In the back row the posterior lateral eyes (PLE) are directed sideways and backwards. They are not visible when the spider is viewed from the front.

The abdomen is flat, broadly oval, and widest near the rear. It is often yellow with reddish-brown markings, but the background color can change to white or pale green to blend in with the vegetation. On the front half of the abdomen there is a central stripe and two lateral stripes. On the back half, behind the central stripe, there are two rows of closely-spaced spots converging at the rear of the abdomen and forming a capped V shape."

From Larry Webber, Alan shares this description of the species:

“either yellow/orange, white, or pale green.  The legs have bands around them near the ends, and a pattern of spots converging toward the tip of the abdomen.  There are stiff hairs on the body.”

Finally, Bonnie notes that according to Arachnids of North Carolina, females have unbanded legs while the males have dark rings on their legs—suggesting that this is a male.

Congratulations again to Alan, Bill, Bonnie, Carol, Eric, and Mike. And thanks to everyone who submitted an answer.

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