By: Sarah Adams
Member of the Big Country Master Gardeners
This month’s bug is the Orbweaver. Orbweavers are in the Animal Kingdom, Phylum Arthropoda, Class Arachnida, and the Order Araneae. Araneidae is a family of a diverse group of spiders known for their intricate web structures and significant ecological roles. These spiders live around the globe, and various species are commonly found in urban, suburban, and natural settings. Several species of orbweavers can be found in Abilene. The most commonly observed include the Yellow Garden Spider (Argiope aurantia), the Spotted Orbweaver (Neoscona crucifera), and the Barn Spider (Araneus cavaticus). Each of these spiders have distinct characteristics and prefer specific types of habitats within the urban and suburban landscapes of Abilene. Abilene and the surrounding counties provided a very hospitable environment for these spiders due to the climate and vegetation.
Orbweavers are highly adaptable and can thrive in a variety of habitats, including forests, grasslands, gardens, and urban areas. In Abilene, we see them in gardens, parks, and around homes where they can build their webs between shrubs, trees, and man-made structures. They can also be found in our vegetable gardens within tomato plants and on okra stalks. I leave any webs that I have in the garden so that the webs will catch squash bugs and mosquitos!
Most people – including me – are quite startled when they first see a Yellow Garden Spider (Argiope aurantia) because they are large, have a yellow and black color scheme, and are on a large web. Further, these spiders just appear overnight and seem to appear in places where no spiders have been seen before. And if you get too close, you may see the spider vibrate its web, which is to make the spider look larger to animals which might do it harm.
After my initial surprise, I remember that they are considered beneficial “bugs” because they play a crucial role in controlling insect populations. They eat aphids, flies, grasshoppers, mosquitoes, moths, and wasps. Of course, they will also eat almost anything caught in their webs, including bees, butterflies, and dragonflies. But still, most gardeners appreciate these spiders and like seeing them in the garden. Their webs serve as effective traps for flying insects, including mosquitoes, flies, and beetles. By regulating these insect populations, orbweavers help maintain ecological balance and reduce the spread of diseases such as West Nile Virus, which is transmitted by mosquitoes. Further, because they prey on common garden pests, these spiders reduce the need for chemical pesticides, promoting a healthier and more sustainable gardening practice.
Orbweavers are known for their orb-shaped webs with a thick thread in the middle of the woven zig zag pattern, which are constructed using silk produced from their spinnerets. The large spiders you see on the web are the females. The males are much smaller and most die after mating. These webs are not only functional but also demonstrate intricate geometric patterns. The construction process involves laying down a framework of non-sticky silk threads followed by the addition of sticky spiral threads to capture prey. When an insect becomes ensnared in the web, the orbweaver quickly immobilizes it with silk and delivers a venomous bite. This venom contains digestive enzymes that liquefy the prey’s insides, allowing the spider to consume it efficiently. This method of feeding is energy-efficient and enables orbweavers to sustain themselves in various environments.
For the most part, orbweavers die in the winter, leaving behind one of more egg sacs which hold hundreds of eggs, but the chances of these eggs hatching are small. In one study over a three-year period, more than 97% of the egg sacs were damaged by birds. And over half of the sacs observed held parasitic wasps or parasitic flies. If the orbweaver eggs survive, small spiders will hatch in the spring, when the weather warms, biting a tiny hole through the sac for them all to crawl out of. Even after emerging, many will not live to adulthood.
Orbweavers often come into contact with humans, particularly in gardens and around homes. These spiders are generally harmless to humans, they are not aggressive and rarely bite humans. Education about orbweavers’ beneficial roles can help mitigate fear and promote coexistence. Highlighting their harmless nature and their contributions to pest control can foster a more positive perception even if they initially scare us!
If you have any questions, call the Taylor County Extension Office at 325-672-6048 or email us at mgardeners@yahoo.com. We hope you visit bcmgtx.org for information on all Big Country Master Gardener events, like us on BCMGA Facebook, and check out training presentations on BCMGA YouTube. We are here to help you.
