I was out in my garden the other day and saw several kinds of spiders. Some were tiny and others were much larger. I wondered how many spider species were in my garden.
I see their webs everywhere. Some webs are sheet webs spanning plants. Others place single silk strands across pathways, just where I walk into them.
How Many Spiders Are in the World?
The exact number of species of spiders is unknown. Worldwide there are over 42, 000 spider species. In North America there are at least 3,807 spider species. Many of these species are small and are about an eighth of an inch.
The smallest spiders live along the ground under rocks and fallen leaves. These small spiders are are still a mystery because they’re rarely studied.
Few scientists study spiders. That is a wonderful opportunity for citizen scientists to study, observe, and compile information on little known or studied species. See Citizen Science and Nature Journal Keeping and Grinnell Scientific Journal.
I like spiders in my garden. A spider’s role in the ecosystem is that of a predator. Their meals comprise a wide variety of prey. Some spiders specialize and eat one type of prey. It delighted me when a large Black and Yellow Garden Spider captured a Lantern Fly in her web and later devoured it. Here is the video from last year, Getting Rid of the Spotted Lantern Fly.
Orb Weaver Spiders
Orb Weavers are spiders that weave the circular, radiating webs we think of as a spider web. There are seven families of spiders that weave orb webs. The two spiders I focus on here are members of the Family Araneeidae. This family includes 3,020 species. In North America has 161 species in this family.
Orb Weavers have poor eyesight and sense their prey by vibrations along the strands of the webs. When prey gets caught in the web, the spider rushes out and wraps the prey in a silk cocoon. Once the prey is wrapped up, the spider will bite it and paralyze it with its venom.
The spider doesn’t eat the prey right away but might cut the cocoon wrapped prey from the web and carry to the hub of the web or another retreat. Sometimes they wrap the prey and save for later feasting.
Many spiders in the orb weaver family are large and colorful. The two spiders I write about here are very common all over the United States. Both weave a zigzag shaped stabilimentum in the center of the web. Scientists don’t know what function the stabilimentum performs.
Black and Yellow Garden Spiders
Black and Yellow Garden Spiders (Argiope aurantia) are boldly colored and conspicuous in the garden. It is the female of the species that is the large. The males are tiny. It was a female Black and Yellow Garden Spider which caught the Lantern Fly in my garden.
Females have large egg-shaped abdomens with black and yellow markings. The legs have alternating bands of yellow and black markings. The bands are not of equal sizes. Males are not as boldly colored as the female; they are paler or orange. The juvenile female’s black and yellow markings are paler or silver.
These spiders live all over the United States in gardens and meadows. They mature in summer. Summer is when you will see the large distinctive females and their radiating webs. The spiders are present through the fall.
Both the Black and Yellow Garden spider and the Banded spider profiled below make egg cases in the fall which hatch in the spring. The males are tiny compared to the females.
Banded Garden Spiders or Banded Orb-Weaving Spider (Argiope trifasciata)
Banded Garden spiders are very common and widespread in the United States and southern Canada. Apparently, this species was originally indigenous to North America but has spread across the world. It is not as common as the Black and Yellow Garden Spider here in Pennsylvania. The Banded Garden spider is smaller than the Black and Yellow Garden spider.
The Banded Garden spider is another large orb-weaving spider found in gardens, fields, and shrubby areas. Large mature spiders appear in summer. We find the tiny males in summer through autumn. The large females appear in late summer through December.
The large female has thin alternating bands of yellow, black, or silver horizontally across the top of her abdomen. Underneath, the abdomen has markings of yellow and rust with a black hourglass shape.
Spiders Are Our Friends
Spiders have important roles in the ecosystem. The prey on insects that can be harmful to our food crops and help with infestations. We know little about the spiders who share our homes and gardens.
I book I have used to learn more about spiders is Common Spiders of North America by Richard A. Bradley (Amazon affiliate link). It is the only book I know solely devoted to spiders. It was helpful in writing this post.
Other Posts on Garden Predators
Last week’s post: Blazing Stars Attract Pollinators and Birds to Your Garden
Whose Egg Case? The European Mantis
More on Orb-weaver Spiders (Wikipedia)
Bugs, Spiders Keep NYC Clean by Eating Garbage
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