How to Get Rid of Webworms in Pecan Trees

Fall webworms on pecan trees look alarming but are manageable with a combination of physical removal, well-timed sprays, and encouraging natural predators. The silky, expanding webs that enclose branch tips are built by colonies of caterpillars (the larvae of the moth Hyphantria cunea), and they can defoliate large sections of a mature pecan if left unchecked through multiple generations. Which removal method works best depends mostly on how tall your tree is and how severe the infestation has become.

Know What You Are Dealing With

Fall webworms are not the same pest as eastern tent caterpillars, though the two get confused constantly. Tent caterpillars build their webs in the crotches of branches in early spring; fall webworms build theirs at the tips of branches from late spring through fall. On pecans, the webs start small and expand outward along the branch as the caterpillars eat through the enclosed leaves. Each web can contain dozens to hundreds of larvae feeding together. A single female moth lays several hundred eggs in a mass on the underside of a leaf, often covering the mass with fine white hairs from her abdomen.

Two distinct races exist in the United States. The black-headed race tends to appear earlier in the season, with eggs laid in mid-March in southern states and larvae hatching by mid-April. The red-headed race follows about four weeks later, laying eggs in double-layer masses rather than single layers.¹ This distinction matters because it affects when you should start watching your pecans for the first webs of the season.

Why Pecans Get Hit Repeatedly

In northern states and Canada, fall webworms produce only one generation per year, so a single round of treatment can solve the problem. In the southern United States, where most commercial and backyard pecans grow, the story is different. The black-headed race can produce up to five generations per year, and the red-headed race up to four.¹ That means new webs can keep appearing from April through October in places like Louisiana, Texas, and Georgia. Climate warming is projected to push generation counts even higher, particularly in southern and lower-latitude regions.²

For pecan growers, this multi-generation cycle means control is not a one-and-done event. You need to monitor trees through the entire growing season, watching for new webs each time a generation of moths emerges. The early-season generations tend to be smaller and easier to catch when the webs are new. Late-season generations, particularly in August and September, are the ones that produce the most dramatic defoliation because the caterpillar populations have been building all summer.

Physical Removal for Small and Medium Trees

If you can reach the webs, tearing them out is the fastest and most satisfying solution. A long pole with a hook, nail, or even a broom at the end works well for pulling webs apart. You do not need to remove every strand of silk; the point is to break open the web so that the larvae inside are exposed to predators, weather, and parasitic wasps. Many gardeners wrap the pole end with cloth to snag the webbing more effectively.

Once the web is torn open, the caterpillars scatter. Birds, spiders, and predatory insects make short work of exposed larvae. You can also knock the caterpillars into a bucket of soapy water if you want to kill them directly. Pruning out heavily webbed branch tips is another option for smaller trees, though avoid cutting large branches just to remove a web. The tree will recover from the defoliation faster than it will recover from a bad pruning cut.

Physical removal works best when you catch webs early, while they are still small and close to the branch tip. Once a web has expanded to enclose a two-foot section of branch, tearing it apart becomes messier and less complete. Walk around your pecan trees weekly during webworm season and deal with new webs when they are the size of a softball. Waiting until they are the size of a beach ball makes every method harder.

Letting Nature Do the Work

Fall webworms have an enormous roster of natural enemies. A global checklist compiled from research across the pest’s entire range documented 488 natural enemies, including 289 predators and 199 parasitoids. The predators span insects, spiders, birds, amphibians, and even a centipede species. The parasitoids alone come from 18 insect families.³ In Louisiana, one study identified 36 species feeding on webworm larvae, including one bird species, 16 insects, and 19 spiders.⁴

What this means in practice is that if you maintain a reasonably biodiverse yard, a lot of the cleanup happens without your involvement. Paper wasps are particularly aggressive webworm predators. They tear into the silk and carry larvae back to their nests. Encouraging paper wasps by leaving their small nests undisturbed in eaves and sheds, where they are not a nuisance, gives you free pest control on nearby pecans. Similarly, birds like blue jays, mockingbirds, and titmice actively feed on exposed webworm caterpillars. Tearing open webs manually amplifies the impact of these predators by giving them access to the larvae inside.

Parasitic wasps are another major force. Several species lay their eggs inside webworm caterpillars or pupae. The wasp larvae consume the host from within, killing it before it can become a moth. You will never see most of these parasitoids at work because they are small and inconspicuous, but they can significantly reduce webworm populations from one generation to the next. Broad-spectrum insecticide sprays kill these beneficial wasps alongside the webworms, which is one reason why measured, targeted control is better than blanket spraying.

Bacillus Thuringiensis and Other Spray Options

For infestations too large or too high for physical removal, spraying the foliage around and within the web is the standard approach. The most commonly recommended product for homeowners is Bt (Bacillus thuringiensis var. kurstaki), a naturally occurring soil bacterium that kills caterpillars when they eat treated leaves. Bt is highly specific to caterpillar larvae and does not harm birds, bees, spiders, or parasitic wasps, making it a good fit for integrated pest management.

The key with Bt is timing. It works best on young caterpillars, roughly in their first few instars. Older, larger larvae are much less susceptible. Because the webworms are feeding inside a silk enclosure, the spray needs to penetrate the web or be applied to foliage just outside it that the expanding colony will soon eat. Using a high-pressure sprayer to break through the web silk improves contact. Applying Bt in the evening or on an overcast day helps because the bacteria degrade quickly in direct sunlight.

Spinosad is another biorational option derived from a soil bacterium, effective against caterpillars and available in homeowner formulations. It has a broader kill spectrum than Bt, so it carries a somewhat higher risk to beneficial insects, particularly bees, when applied to flowers. On pecans, which are wind-pollinated, this is less of a concern than on fruit trees, but applying in the evening when pollinators are inactive is still smart practice.

Conventional broad-spectrum insecticides containing carbaryl, permethrin, or bifenthrin will also kill webworms, but they bring collateral damage. They wipe out the predatory insects and parasitic wasps that would otherwise help control future generations. In a backyard setting with one or two trees, targeted Bt applications plus physical web removal usually make chemical insecticides unnecessary. In a commercial pecan orchard, the calculus shifts toward whatever gives the fastest knockdown, but even there the trend in integrated management is toward selective products.

Trunk Injection for Tall Pecan Trees

Mature pecan trees routinely reach 70 to 100 feet, and spraying the canopy of a tree that tall requires commercial equipment most homeowners do not have. Trunk injection offers an alternative: the insecticide is delivered directly into the tree’s vascular system through small holes drilled in the trunk, and the tree distributes it to the leaves over the following days and weeks.

Research on trunk-injected emamectin benzoate in pecan trees showed promising results against webworm larvae. In leaf-feeding tests, all four dosage levels tested caused significant mortality in fourth-instar fall webworm caterpillars. At 10 days after injection, mortality rates ranged from about 65% at the lowest dose to roughly 85% at the highest. By 60 days post-injection, the lowest dose had faded to about 26% mortality, while the highest dose still achieved around 82%.⁵ The study also assessed food safety and found the approach viable for pecans destined for consumption.

Trunk injection has real advantages for large trees. It avoids spray drift, keeps the insecticide out of the air and soil, requires no specialized spray rig, and delivers the chemical directly where the caterpillars are feeding. The downside is cost: the injection equipment and the product itself are more expensive per tree than a tank of Bt, and the drilling creates small wounds that the tree must seal. For a homeowner with one towering pecan that gets hammered by webworms every year, though, a single trunk injection early in the season can provide weeks of protection across those hard-to-reach upper branches.

When Webworms Are Not Worth Fighting

Here is the part many pest-control articles skip: in many cases, fall webworms on pecans are a cosmetic problem, not a threat to the tree’s health or nut production. Pecans are large, vigorous trees with enormous leaf canopies. A web or two on the branch tips, even a dozen, may look ugly but removes only a small fraction of the tree’s total foliage. The tree can replace lost leaves or simply carry on with what remains.

Defoliation becomes a real concern when webworms strip a large percentage of the canopy, especially late in the season when the tree is filling its nuts. Pecans depend on leaves to feed the developing kernels from August through October. Severe late-season defoliation can reduce nut size and fill, and repeated heavy defoliation year after year can weaken the tree over time, reducing its vigor and making it more susceptible to other stresses. But a moderate webworm presence in June or July, when the tree has plenty of time to recover, rarely causes meaningful yield loss.

The practical upshot: if you have a large pecan with a few webs high in the canopy and you cannot easily reach them, it is perfectly reasonable to leave them alone. Monitor to make sure the infestation does not escalate, but do not panic over every web. Intervention makes the most sense when webs are multiplying rapidly, when late-season generations threaten the nut-filling period, or when a young tree with a small canopy cannot afford to lose much foliage.

A Seasonal Game Plan

Putting this together into a practical schedule for southern pecan growers looks something like this:

• March through April: Watch for the first egg masses and tiny webs from the black-headed race. This is the easiest time to remove webs by hand because the colonies are small and the caterpillars are young.
• May through June: The red-headed race appears, and the first generation of the black-headed race is producing moths for generation two. Continue physical removal. If webs are too high to reach, apply Bt or spinosad to surrounding foliage while caterpillars are still small.
• July through August: Population peaks hit. Third and fourth generations can overlap. This is when infestations go from tolerable to ugly. Spray if needed, prioritizing trees where late-season defoliation would hurt nut development.
• September through October: Final generations appear. Webs this late in the season are the most damaging to nut quality. If trunk injection was done earlier, residual activity may still be providing some control. Otherwise, targeted spraying or physical removal remains the approach.

Growers in northern states with only one generation per year can focus their entire effort on a single window, typically June or July, and be done.

Mistakes That Make Webworms Worse

The single most counterproductive thing homeowners do is torch the webs with a propane torch or lighter. This advice circulates on social media and in older gardening books, and it sounds satisfying, but it damages the tree far more than the webworms would have. Scorching bark, killing cambium tissue, and burning branch tips creates wounds that invite wood-boring insects and fungal diseases. The webworms you were worried about would have caused temporary leaf loss; the fire can cause permanent structural damage. Do not burn webs on any tree, but especially not on pecans, which are valuable and long-lived.

Another common mistake is spraying the outside of the web with a contact insecticide and calling it done. The silk acts as a barrier, and a quick exterior application may not reach the caterpillars inside. Breaking the web open first, or using a high-pressure nozzle to penetrate it, dramatically improves spray contact. Alternatively, focus spray on the fresh foliage just outside the expanding edge of the web, which the caterpillars will eat as they grow outward.

Finally, applying broad-spectrum insecticides on a calendar schedule “just in case” is a recipe for killing the natural enemy community that keeps webworm populations in check between outbreaks. The hundreds of predator and parasitoid species that feed on webworms are your most powerful long-term allies. Every unnecessary spray removes some of that pressure and increases the chance that the next webworm generation explodes unchecked.

Webworms Versus Pecan-Specific Pests

Fall webworms are generalists. They feed on over 600 host plant species worldwide, and pecans are just one item on a very long menu. This distinguishes them from pests that specifically target pecans, like the pecan nut casebearer or the pecan weevil, which have life cycles tightly linked to pecan nut development and require different management strategies. A homeowner who sees webs on a pecan and assumes the nuts are under direct attack is often confusing webworm damage (which is to leaves) with the damage these other pests cause to the nuts themselves.

Webworms affect nut production only indirectly, by removing the leaf area that feeds nut development. The nuts inside a webbed branch tip are not being eaten by the caterpillars. This is why moderate webworm infestations often have no measurable effect on harvest: the tree has enough remaining foliage to compensate. When you hear advice about treating for “worms in pecans,” it usually refers to pecan nut casebearers or hickory shuckworms, which bore into the nut itself. Webworms are a canopy pest, not a nut pest, and the distinction matters for choosing the right control method and deciding how aggressively to treat.