Look closerInsects
Fall webworm tents on branch tips: the silk nests explained
When: July to October
Those gauzy silk bags swallowing whole branch ends on cherries and other hardwoods are fall webworm nests, with the caterpillars feeding safely inside the web.
Why this time of year
The webs start small in midsummer and swell through August and September as the caterpillars enclose more leaves, so late summer is when they suddenly seem to be everywhere along the roads.
How to notice it
- Scan roadside cherries, crabapples, and birches for silky webs at the tips of branches.
- Look closely at a low one: the caterpillars stay inside the web and eat the leaves it encloses.
- Compare with spring's tent caterpillars, which build in the fork of the trunk and leave the tent to feed. Tip of the branch means fall webworm; fork of the tree in spring means tent caterpillar.
- Leave the web be; the tree does not need rescuing.
Try this with kids: Can you find a web with the caterpillars still moving inside it?
a webworm is a caterpillar that spins a shared silk web over the leaves it eats
Sources
- umass.eduWebs are typically found on the terminal ends of branches, encircling twigs, shoots, and shredded leaves; small webs appear in mid-July in Massachusetts but are often not noticed until fall; hosts include dozens of hardwoods; injury to the host plant is mostly aesthetic, and an unstressed tree's overall health is often not impacted.
- extension.unh.eduThe dirty loosely-woven web of the fall webworm encloses branches and the larvae feed within it, whereas the eastern tent caterpillar's web is thickly constructed in the forks and crotches of trees in spring and those larvae leave the tent to feed.
- extension.unh.eduSilky nests in wild cherry, fruit trees, and some maples are fall webworm; nests grow larger in late summer and early autumn as larvae move to new areas to eat; most damage comes late in the growing season when leaves have already done most of their work, so healthy trees are not threatened.
In the guide for July, August, September, October