A spider that acts like a cat

If I were a dragonfly, wasp or bee flying over a lake in search of a place to land, I’d stay away from peelbark St. Johnswort, Hypericum fasciculatum, a yellow-flowering, shrubby plant that grows in and around wetland areas.

I’d be especially cautious September through November when female green lynx spiders living on St. Johnswort plants are guarding egg sacs and young spiderlings. Spiders are always looking to catch a flying insect that unwittingly lands on the wrong plant at the right time. That’s especially true when they’re raising babies.

And there’s a lot of baby-raising going on among arachnids living on plants in our lake right now.

Green lynx spider with egg sac on peelbark St. Johnswort

The other day while out rowing, I decided to take a survey of peelbark St. Johnswort shrubs and green lynx spiders, Peucetia viridians. Of the 340 plants I tallied, more than 7 percent contained a hungry and protective mama spider. Most of the spider-inhabited plants were located a short distance away from other St. Johnsworts, and I never saw more than one adult female arachnid on any plant.

Spiders were more likely to choose isolated plants like this one on which to raise young 

Since autumn is a green lynx spider’s reproduction season, each of the 24 spiders was either protecting an egg sac or guarding newly hatched spiderlings.

A green lynx spider’s egg sac is much easier to spot than the spider itself. The sac is a slightly bumpy, sand-colored container housing up to 600 bright orange eggs that will hatch within 11 to 16 days. The sac is about an inch diameter with one flat side and one rounded. After its construction is complete, the female spider surrounds the sac with a sketchy tent of randomly woven silky threads. She then protects it further by clutching it with her legs as she hangs upside down.

Lots of bright orange eggs surround this green lynx spider's egg sac along with a captured dragonfly 

Although birds may present the most obvious danger to lynx spiders, ants are a serious threat as well. Ants chew through egg sacs and carry away eggs. They can also attack adults. Perhaps choosing to raise young on an isolated plant in a waterlogged location makes it harder for ants to harm them.

Whatever their reason, female lynx spiders continue to protect their offspring until they can fend for themselves, which happens about 10 days after they hatch. When the young spiders are ready to leave, they do so by “ballooning.” They climb to the highest point they can reach, stand up on their hind legs and produce slim strands of silk that create a sort of a parachute to float them away on their random flight for life.

Green lynx spiderlings almost ready to 'balloon'

I have yet to observe spiderlings take flight, but I’ve marveled at the progress of egg sac development through the early stages of spiderling growth. I’ve also noticed a wide variety of invertebrates captured by female lynx spiders.

Wasp held in the clutch of a green lynx spider

Unlike spiders that spin webs, a green lynx catches food by leaping onto whatever hapless prey lands nearby. As its name suggests, this predatory arachnid has a cat-like ability to run fast and jump far. It also has keen eyesight, thanks to eight eyes positioned in such a way to monitor its surroundings from multiple directions simultaneously.

I like the way a green lynx spider’s well-camouflaged body make it hard to find unless you know where to look and what to look for. I admire the diligence with which females guard and protect their egg sacs, and I appreciate the way these relatively small spiders — females are a little less than an inch long with males half that size — fearlessly pursue prey far bigger than themselves.

Although just the thought of spiders strikes fear in many people, I think these eight-legged arthropods are beautiful creatures that provide an important service by eating insects that harm plants and bother people. Of course, not all the prey caught by arachnids can be considered a problem. Some of their victims are beneficial insects like potter wasps, honeybees and dragonflies.

That’s why if I were a dragonfly, wasp or bee, I’d stay clear of peelbark St. Johnswort plants — at least in autumn on small lakes in Central Florida. Doing so may not assure my safety, but it could prevent me from becoming the next meal for a green lynx spider.