Lace bug on filbert

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Alder lace bugs are the secondary problem and often we'd let them run their course. However, when we're trying to control a serious disease it's good to relieve the plant of other stresses, too. 

Lace bug on filbert:

When Harry has a lacy problem

Noticing this pest
Controlling the insects
Applying this to other lace bugs

The leaves of this Harry Lauder's walking stick (Corylus avellana 'Contorta') are being sucked dry by insects called alder lace bug (Corythucha pergandei).

Below: The shrub's foliage is discolored. Some leaves are stippled -- marked with many tiny spots that are not chewed but sucked dry so the leaf seems dusty and dry. On other leaves, larger sections have browned out or gone white. These discolored areas are thin and crumbly.



Below: Looking even closer on the undersides of discolored leaves, we see exoskeletons shed by growing insects and dark spots of insect frass -- excrement.


Controlling lace bugs

In winter while the plant is leafless, lacebugs are pretty much untouchable. Then they are well protected from contact killers because they're in bark crevices or leaf litter. They're immune to other poisons since they are not eating.

So, in the spring after you see such damage, wait a few weeks after this shrub's budbreak, until redbuds bloom. Then. look at some leaf undersides for signs of the lace bugs' return. If we see them or their damage, apply an insecticide. Be sure to coat the underside of the the foliage.

Almost any insecticide including soap will kill lace bugs when they are just out of the egg in early spring.

In spring you may see the tiny dark eggs partially inserted into the leaf underside. If so, wait one week and then check again before applying an insecticide, since most insecticides can't kill insects still in the egg. Alternatively, apply a horticultural oil which if applied shortly before the hatch will coat and smother the emerging insect.

In any event, re-check monthly, because lace bugs have several generations each year. Spring survivors can multiply prodigiously.

Other lace bugs, same handling

There are many lace bug species, each peculiar to one or a group of plants. The various lacebugs cause their hosts similar damage and are handled the same way.

  • Sycamore (Platanus) has sycamore lacebug, which can also host on ash, hickory and mulberry
  • Cherry has its own lacebug
  • Azaleas and rhododendrons are host to azalea lacebug
  • Alder can share its lacebug with elm, birch and hazel
  • Hawthorn and quince can share a lacebug
  • Walnuts, butternuts and lindens have walnut lacebug in common
  • Aster lacebug gets around to many daisy/aster relatives
  • Poplar lacebug can live on poplar, willow, mountain ash, beech and maple

More about lace bugs

"…Nymphs are spiny and (dark)… …can be found clustered among their dark feces and cast nymphal skins on lower leaf surfaces. …The black eggs are elongate and placed on end in small groups on the underside of leaves."

"Tolerate lace bug damage where possible; in most cases, it does not seriously harm plants. Provide proper cultural care so plants are vigorous. …Natural enemies of lace bugs include assassin bugs, lacewing larvae, lady beetles, jumping spiders, pirate bugs, and predaceous mites. These predators may not appear in sufficient numbers until after lace bugs become abundant; their preservation, however, is an essential part of a long-term integrated pest management program."