Spotted lanternfly
Lycorma delicatula
A spectacular invasive planthopper that swarms grapevines and trees, raining honeydew and sooty mold beneath. Scrape the mud-colored egg masses off in winter and report it.
How to know it
At rest a gray-brown moth-like wedge 25 mm long with black spots; in flight it flashes a scarlet hindwing barred with black and white — nothing else in a North American garden looks like it. The nymphs are black with white spots, turning bright red and black in the last stage. The egg masses look like a smear of dried gray mud on bark, stone or garden furniture.
What you'll see
- Dozens or hundreds of insects massed on a trunk or a vine at once, often in a band at chest height.
- Weeping wounds running down the bark, sour-smelling and attracting wasps and ants.
- Everything below the plant sticky with honeydew, then blackened with sooty mold.
- Grapevines losing vigor year on year, with poor ripening and winter dieback.
- Gray putty-like egg masses on bark, fenceposts, stone and the underside of anything left outdoors.
Where it comes from
One generation a year. Eggs laid in autumn hatch in spring; the nymphs work up through four stages on soft growth, and the adults appear in midsummer and move onto woody hosts, especially tree of heaven and grape. Egg laying runs from September to the first hard frosts. It moves mainly by hitchhiking — on vehicles, firewood and nursery stock — rather than by flying.
Established across much of the mid-Atlantic and spreading. Tree of heaven nearby is the strongest predictor of heavy numbers, and grapes are the crop that actually suffers; most established trees tolerate it better than the spectacle suggests.
Dealing with it
- Scrape egg masses into a bag of alcohol or hand sanitizer through the winter — each one is 30 to 50 insects not hatching.
- Band trunks with a circle trap that funnels climbing nymphs into a bag; avoid open sticky bands, which catch birds and squirrels.
- Swat, squash and vacuum the adults, which is more effective than it sounds because they jump forwards into your hand.
- Protect grapevines with fine mesh through the adult season if the planting is small.
- Report a sighting to your state agriculture department if it is new to your county, and check vehicles before traveling.
Keeping it out
- Remove tree of heaven from the property, or keep one male tree as a treated trap tree.
- Check anything stored outdoors — furniture, pots, trailers, firewood — for egg masses before moving it.
- Wash off the honeydew and manage the sooty mold on plants beneath a heavily infested tree.
- Keep grapevines well watered and fed; the damage is cumulative stress rather than a single strike.
- Do not move firewood, which is how it travels furthest and fastest.
What it goes for
Grapes above all, then tree of heaven, walnut, birch, willow, maple, hops, apples, plums and peaches.
Trouble it brings with it
Who hunts it for you
- Garden birdsPasseriformes Both things are true: birds strip your currants and a brood of blue tits takes several thousand caterpillars out of one fruit tree in a fortnight. Net what you must and welcome them everywhere else — a nest box near the apples is worth more than a spray. Grow to recruit it: Echinacea,Elderberry,English holly,Goldenrod,Rudbeckia,Sunflower
- Praying mantisMantidae A sit-and-wait ambusher that snatches caterpillars, beetles, and anything else that wanders close — friend and foe alike, so count it a mixed blessing. Tall, structured plantings give it perches and egg-case anchors. Grow to recruit it: Cosmos,Fennel,Sunflower
- SpidersAraneae Webs, ambushes, and night patrols make spiders the garden’s steadiest generalist predators, taking whatever flies or crawls past. Mulch, ground cover, and undisturbed corners keep the population dense. Grow to recruit it: Lavender,Thyme
See also
The Cottage Garden Companion — the gardener's bestiary at cottagegardencompanion.com