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The cutest spider in the garden

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By The Staff

I have a lot of spiders around my place. It seems like there are more this year, maybe because we had a nice, wet winter. The spider I particularly like is the spiny orb weaver (Gasteracantha cancriformis), a Florida native. These spiders look like little flat crabs with white shells, with black spots and six-pointed red spines around the outside edge. That’s why their common name is “crab spider.”

Spiny orb weavers build the typical “wagon wheel” web design (one of four kinds of webs that spiders weave). There is a basic design of a central hub, radial lines like wheel spokes extending out from the hub and a sticky spiral of adhesive silk.

A web can be built in about a half hour. This is a good thing because it nearly killed me to sweep all the spider webs from my deck to prepare for a big party last month. Luckily, my husband is kind and pointed to the one I had “forgotten” and asked if I was keeping it for show and tell.

A spider at the center of its web can immediately detect where in the web its prey is trapped. Then the spider may “pluck” at the web to determine how big the prey is. It then runs down the radial lines to bite and/or wrap the insect for lunch.

Spiders know where to step so they don’t get stuck in their own webs. And they have an oily substance on their little feet, just in case.

The smaller males can be found dangling from a single thread from the females’ webs prior to mating. I haven’t seen any little males although they could have been dislodged during the big sweep.

The egg sacs are deposited on the undersides of leaves adjacent to the female’s web from October through January. The egg mass consists of 101 to 256 eggs. How they determine this number is pure science.

After the eggs are laid on a white silken sheet and wrapped and wrapped with white silk, a line of green silk thread is woven along the long side of the egg mass. They take 11- to 13 days to hatch then go through several other stages before actually becoming “spiderlings.” The eggs are a favorite treat of the humpbacked fly.

The webs many times have these thicker white zigzagged tufts of silk, mostly around the outside. These are called stabilamentum. Orb weavers and other spiders make these on their webs. Scientists think the reason these spiders make stabilamentum is that they may deter birds from flying into their webs and having to start all over.

Little spiny orb weavers eat whiteflies, regular flies, moths, and beetles. They have many orb weaving cousins. This family is one of the larger spider families in the insect world with several dozen species alone in Florida. They like to hang out by your house and also enjoy living in orange groves.

Material for this piece was provided from Florida’s Fabulous Spiders by Sam Marshall and G.B. Edwards and Featured Creatures/IFAS/Dept of Entomology and Nematology.

For more information about gardening practices in Central Florida, call Marion County Master Gardeners at 671-8400, or visit their office in the Cooperative Extension Center, 2232 N. E. Jacksonville Rd.