One day, your tree looks completely normal. Then the next, it’s draped in creepy-looking webs. Why is that?
That, friends, is what happens when fall webworms or Eastern tent caterpillars pay a visit. They spin showy nets that sort of make it look like a tree is covered in spider webs.
Read below for more about these web-making caterpillars, including what trees they’re drawn to and how to deal with them.
Caterpillars creating messy webs in trees is a common nuisance for many homeowners. These unsightly silk structures often cover branches and leaves, sometimes enveloping entire trees. While the sight can be jarring, these tent-like webs serve an important purpose for the caterpillars inside
Why Do Caterpillars Make Web Nests?
Caterpillars build web nests for food, shelter, thermoregulation, wind protection, and to prevent other caterpillars from eating young leaves The key reasons include
Food
Web nests allow caterpillars to feed safely on the enclosed leaves without competition As they eat all the foliage inside, the colony expands the web to incorporate more leaves.
Shelter
The thick webbing helps conceal the caterpillars from predators like birds and wasps. It’s much harder for these animals to spot and reach the larvae inside.
Thermoregulation
Living together in a web helps caterpillars stay warm, especially on cool nights. The group can huddle together, pooling their body heat.
Wind Protection
The sturdy silk barriers shield caterpillars from gusts that could blow them off branches. Some anchor themselves with a single tether thread.
Resource Guarding
Building webs around young, tender leaves prevents other insects from accessing them. It reserves the best food for the web builders.
10 Common Caterpillars That Make Web Nests
Below are 10 of the most widespread caterpillar species known for constructing web nests:
1. Eastern Tent Caterpillar
This caterpillar builds tents in tree branches, mostly favoring cherry, apple, and ash trees. The dark larva has blue spots and brown hairs.
2. Fall Webworm
These caterpillars enclose branches tips in loose, transparent webbing. They mainly attack pecan, cherry, walnut, and persimmon trees.
3. Western Tent Caterpillar
Found west of the Rocky Mountains, this species constructs thick, white silken tents. It primarily infests apple, cherry, cottonwood, and aspen trees.
4. Southwestern Tent Caterpillar
Prevalent in the Southwest, it makes web nests on cottonwoods and willows. The bright green caterpillar has black spots and tufts of gray hair.
5. Ailanthus Webworm
Known for webbing paradise tree leaves together to feed. The adult moths visit flowers instead of trees.
6. Striped Oak Webworm
Builds tents enveloping young oak leaves before maturing to eat entire foliage. The green caterpillar has yellow stripes outlined in red.
7. Pacific Tent Caterpillar
Spins white silken tents on oak, cherry, apple, and other broadleaf trees. Common in California and the Southwest.
8. Lackey Moth Caterpillar
Devours young oak and apple leaves within surrounding webs. The hairy blue-gray larva has white and yellow dots on its back.
9. Ground Lackey Caterpillar
Makes a series of web tents in coastal habitats to feed on low marsh vegetation. Uniquely colored bluish-gray and black.
10. Red-spotted Leafroller
Rolls leaves together with silk strands to form a sealed web nest. Damages fruit trees and ornamental plants. Larva has red dots.
Are Caterpillar Web Nests Harmful?
Caterpillar webbing rarely severely damages trees. The foliage loss is mostly aesthetic unless the tree is already stressed. Still, major infestations can defoliate entire branches. Pruning out webs early before they spread often helps reduce impact.
In most cases, birds and beneficial insects naturally control caterpillar populations. But if web nests become excessive, property owners can consider safe organic measures like applying BT (Bacillus thuringiensis) or spinosad bacteria during early spring. This targets young larvae before webs grow large. Avoiding chemical pesticides reduces risks to pollinators and wildlife.
While unsightly, web-building caterpillars still play an important ecological role. Their silk tents feed and shelter other essential insects like parasitic wasps that help regulate pests. With a little maintenance, trees rebound quickly once caterpillars complete their life cycle.
Caterpillars create web nests mainly for food, shelter from predators, thermoregulation, and protecting resources. Several common species like Eastern tent and Fall webworm caterpillars build messy but mostly harmless webbed structures in trees. Monitoring for early infestations and pruning out initial webs can help prevent major defoliation. But in most cases, nature balances itself, and web nests indicate a lively ecosystem. With a little patience, caterpillars and trees bounce back on their own.
How To Care for Flowering Trees & Shrubs Year Round Learn how to care for flowering trees and shrubs year-round with our comprehensive guide. Discover when to cut back flowering trees and shrubs and what season they should be pruned to ensure healthy growth and vibrant blooms in your landscape.
Insect & Disease Issues
Webworm Vs Eastern Tent Caterpillar
These pests are often mistaken for each other, but a few key distinctions set them apart.
Eastern Tent Caterpillars build fancy nests! ️Yeah not sticking my hand in there #web #caterpillar
FAQ
What kind of caterpillars make webs?
It’s not early Halloween decorations, those web covered branches are actually caused by web spinning caterpillars. The webs, which are best known as cocoons or silken nests, are spun by the two most common pests of deciduous trees: fall webworms and eastern tent caterpillars.
How do I get rid of web spinning caterpillars?
Remove the webs by hand, then kill the tent worms with dish soap. If you only have a couple of tents, pull the webs off the branches. Shoot for early morning or evening when the caterpillars are inside their webs. If you don’t want to touch them, wrap the webs around a broomstick.
Are webworm moths good or bad?
They don’t really do any damage, as caterpillars they’re after problem trees and as adults they pollinate. They feed on the tree of heaven (Ailanthus altissima), which is a pretty bad invasive species. The Ailanthus webworm moths ended up liking those trees so they spread out from their native range.
Why is my caterpillar making a web?
The webbing you see may be the beginnings of a cocoon, which is a silk case that the caterpillar constructs in order to protect its future pupal self.Jun 30, 2021
What is a caterpillar web nest?
Caterpillar web nests are made around one or multiple leaves on a tree or plant. These types of webs often cover the youngest leaves of a tree, which are the softest and the easiest to chew. Seen as the only available food, host plant leaves are often completely eaten by caterpillars which may be responsible for tree defoliation.
What do caterpillars eat inside a web nest?
The leaves of oak trees or apple trees are among the common hosts and foods inside a caterpillar web nest. Caterpillars may live their silk tent for food when they leave inside have been eaten. They do this towards their last instars or growth stages when they are stronger and when they need to feed more.
Do caterpillars make webs?
Some caterpillars make webs that may resemble spider webs in texture and coloring. These types of webs sever different purposes. The species that build these webs may cover trees, plants, and other flowers in their webs. The higher the number of webs on the tree, the higher the actual invasion risks are. Do Caterpillar Have Nests?
What are eastern tent caterpillar webs?
Eastern tent caterpillar webs have a much more thick, cottony texture. You’ll find Eastern tent caterpillar webs in tree “pockets” meaning, where two branches connect, or where a branch connects to the trunk. But fall webworms spin their webs at the very tip of branches. These caterpillars also prefer to feed on different trees.
Are caterpillar web nests good for food preservation?
Other theories argue these web nests are ideal for food preservation. Caterpillar web nests are made around one or multiple leaves on a tree or plant. These types of webs often cover the youngest leaves of a tree, which are the softest and the easiest to chew.
Do caterpillars have nests?
Caterpillars don’t have nests but they can make silk tent-like cocoons. These webs cover multiple leaves which they can safely feed in while inside. Most caterpillars spend just a few weeks inside this silk nest, eventually moving out on their own to find more food. Caterpillars also live in cocoons just before they metamorphose safely.