July 18, 2026

When I went out to load the kids in the Jeep for our walk, I noticed a spider clinging to the window. It is summer in Arkansas, and I have noticed several spider species around our yard and garden. Over the last two weeks we have had an orb-weaver (family, Araneidae) trying to spin her web in the gate that opens from the patio to the side yard. I let the kids out for their final trip before bed around 10 pm each and the spider had nearly completed the web. The kids run through the web guidelines on their way to the side yard and the industrious spider is forced to begin again. The web has not been up the last two nights, but I do not know if this is due to the rain or frustration from having to rebuild. The wolf (family Lycosidae) and trapdoor (infraorder, Mygalomorphae) spiders have not been plentiful, but seems to multiple in fall as they prepare to overwinter. There have been several small Bold Jumping Spiders (Phidippus audax) crawling on the windows or patio furniture. These are easily recognized by their black bodies and distinctive white dot on their abdomen. The spider on my window was a jumper, but another species. I narrowed this to a dimorphic jumper.
When I went online, I found the dimorphic jumping spider (Maevia inclemens) is a relatively common and colorful jumping spider of North America. The males have two forms, which is a very rare phenomenon in zoology, and each use different courting displays. The “tufted” morph has a black body and pedipalps (“palps”), three black tufts across its “head”, and pale legs. The “gray” morph has black and white stripes all over its body and legs, orange palps, and no tufts. Each of the two forms accounts for 50% of the adult males, and they are equally successful in mating. Like all jumping spiders, the dimorphic has excellent vision. The main eyes, in the front-and-center position, are large, and are more acute than those of a cat (Felis catus) and about 10 times as acute as a dragonfly’s (infraorder, Anisoptera). The remaining three pairs of eyes are along the sides of the head, and work as motion detectors. The eyes are used for hunting, for avoiding threats and for finding mates. The species is found in south-eastern Canada, and in the eastern US and is frequently seen on man-made structures like outbuildings or fences (or cars).
I was not surprised to see the dimorphic spider clinging to the glass. I have seen spiders hanging on ceilings and crawling up walls, so a spider on glass was not out of the ordinary. It did make me think again about how they are able to perform this feat. The dimorphic, and many other insects, walk up glass windows using thousands of tiny hairs on their legs that lock onto invisible ridges on the glass. These hairs create weak electrical forces between molecules, pulling the spider to the surface. And making them stick without any glue. Each foot has microscopic hair called setae. Each hair then splits into even smaller branches called setules. These microscopic stetules get so close to the glass that they trigger a natural molecular pull (Van der Waals forces). This force provides a strong grip that holds the spider’s weight. Even though a single Van der Waals interaction is very weak, they collectively have massive structural and physical implications
THOUGHTS: Even though the Van der Waals force used by the dimorphic jumper is very weak, this interaction can have massive structural and physical implications. Molecules with more electrons are more “polarizable,” and these attractions create higher boiling or melting points. The billions of tiny, microscopic hairs on the dimorphic create the adhesion to climb surfaces. Finally, they provide the foundational attraction that allows cell membranes to hold their shape and enables proteins and DNA to fold and interact correctly. Funny what you can learn watching a spider walk up glass. Act for all. Change will come and it starts with you.








