Psyllids
Psylloidea
also called Jumping plant lice, Bay sucker, Box sucker
Jumping plant lice that distort and curl new shoots, most familiar on bay and box. Prune out affected tips; healthy plants shrug off light attacks.
How to know it
Aphid-sized insects, 2–3 mm, that jump like miniature cicadas when disturbed; the flat pale-green nymphs sit inside the curled leaf or the cupped shoot tip, often under a smear of white waxy fluff.
What you'll see
- Bay leaves with thickened, yellow, inward-curled margins that later turn brown and brittle.
- Box shoot tips cupped into a tight little cabbage of overlapping leaves.
- White waxy wool or fluff inside the curled leaf or between the cupped tips.
- Sticky honeydew and sooty mold on the foliage below in a heavy year.
- On apples and pears, blackened sticky shoots and, with pear sucker, a russeted fruit skin.
Where it comes from
Overwintering adults lay on the first flush of spring growth; nymphs feed inside the shelter their own feeding creates, which is why the damage is always on the newest leaves. One to several generations a year depending on species, with adults sheltering in evergreens and bark crevices over winter.
Worst on the spring flush, on clipped evergreens pushed hard with feed and water, and in sheltered town gardens where adults overwinter easily.
Dealing with it
- Clip out the affected tips — on bay and box this is both the control and the tidy-up.
- Delay or skip a nitrogen feed, so the plant is not offering a second flush to colonize.
- Wash honeydew off the lower foliage before sooty mold sets on it.
- Leave light damage on a healthy plant: it is disfiguring, not weakening.
- Prune clipped evergreens after the spring flush has hardened, not before it.
Keeping it out
- Water and feed bay and box steadily rather than in surges that push soft flushes.
- Trim topiary in late summer so the tender regrowth is not out in psyllid season.
- Encourage ladybirds and lacewings, which take psyllid nymphs readily.
- Inspect bought bay standards, which frequently arrive already curled.
- Keep containers of bay out of hot, sheltered corners where numbers build unchecked.
What it goes for
Bay, box, apples and pears above all, with related species on ash, hawthorn, alder and eucalyptus.
Trouble it brings with it
Who hunts it for you
- Ladybird (lady beetle)Coccinellidae The gardener’s favorite ally: adults and their alligator-shaped larvae each eat thousands of aphids, plus scale, mealybugs, and other soft-bodied sap-suckers. Grow flat, open flowers for the adults and never spray a colony that ladybird larvae are already working. Grow to recruit it: Calendula,Cilantro,Cosmos,Dill,Fennel,Yarrow
See also
The Cottage Garden Companion — the gardener's bestiary at cottagegardencompanion.com