Spiders in Tree Holes

Spiders in the Landscape

• Not all spiders spin large, obvious webs. Some are voracious hunters in their own right. These spiders hunt using surprise tactics, such as popping out of small holes when insects happen by and dragging their prey back into the hole with them. Hunting spiders, like jumping spiders, are common in trees, especially if that tree has an insect infestation. Web-spinning spiders may take advantage of larger openings in trees, spinning webs in the relatively protected areas large hollows can provide. Holes in trees can provide all types of spiders with protection from their predators and the elements.

Identifying Poisonous Species

• Any homeowner who finds a spider in a tree will immediately wonder if they're in danger. Luckily, most spiders in the landscape are not dangerous to people or pets, and even the dangerous ones are shy and rarely bite.

  Brown recluse spiders don't weave substantial webs. Instead, they choose to hide in dark holes during the day and hunt at night. These 1/2-inch long, light brown spiders bear a violin-shaped marking immediately behind their eyes, with the neck of the violin extending to the thorax.

  Black widow spiders would be unusual finds in small tree holes, but if your tree cavity is large, these 1 1/2-inch long black and red spiders may weave their webs inside. Males usually are tan in color and shaped much differently from the female, but they're not a bite risk.

Making the Landscape Less Friendly

• Despite the benefits spiders bring to the landscape, when they take up residence in areas that are frequented by children or pets, or the idea of having spiders nearby is just too much to take, you may want to evict them from your tree. Discouraging a few spiders is easy due to their shy nature. Spend a few minutes every day destroying any webs or egg sacs you can see inside the hole with a brush, broom or jet of water from the garden hose. If the spiders are hanging around because of an insect infestation, treat the bugs aggressively to destroy this ample food source. Be sure to remove any debris the spiders might use as an alternative nest site before you attempt to evict them from the tree.

Using Chemicals on Unwanted Spiders

• When you're not sure if the spider you're dealing with is dangerous, or you just need it gone yesterday, consider using chemicals to deal with the little predator. Unfortunately, most sprays aren't very effective on spiders unless they're sprayed directly on the creature. If you have a good line of sight to the spider in the hole, though, a premixed insecticide containing bifenthrin can be sprayed directly inside. Be careful to spray only in the hole, and not splash the chemical on other parts of the plant, since this may accidentally kill other beneficial insects. As with any garden chemicals, read the label completely before spraying the trouble spiders in your tree.