Hemiptera : Miridae

apple-dimpling-bug-damage-800x451px-credit-denis-crawford

Image above: damage caused by Apple Dimpling Bug
(image courtesy of Denis Crawford)

Apple Dimpling Bug (Campylomma liebknechti) is a native sap-sucking insect that damages the fruit of apple and Nashi pear trees. Apple Dimpling Bug occurs across most of southern Australia but does not occur in Tasmania. A related Tasmanian species (Niastama punctaticollis) also called ‘apple dimpling bug’, causes similar problems in Tasmania.

Apple Dimpling Bug is of great importance to the fruit industry, because the damage the bug causes renders fruit unsellable. In the home garden it is not so critical, because the flesh of the fruit is not affected. In other words, you can still eat the fruit. In cotton crops Apple Dimpling Bugs have been recorded feeding on moth eggs and mites (making them predators), but they still feed on cotton (making them a pest). There is no evidence of Apple Dimpling Bugs being predators in home gardens.

Best Treatment for
Apple Dimpling Bug

Apple Dimpling Bug is a minor pest in home gardens. It feeds on a considerable range of native plants, and some other ornamental plants, without causing damage. However, if you grow apples and Nashi pears they can be a nuisance.

The secret to pest control is to keep an eye on your plants so that you can spot pest incursions early. This is especially critical with Apple Dimpling Bugs in fruit trees - because by the time you see fruits forming on your trees, the damage may already have been done.

You could keep an eye out (see Monitor) while you are watering your plants and check for Apple Dimpling Bugs on your fruit trees at pink bud stage. For this to work, you will need to know what Apple Dimpling Bugs look like (see Description).

Prevention is always better than cure. There are several measures that you can do to prevent or minimise damage by Apple Dimpling Bugs (see How to Prevent Apple Dimpling Bugs Appearing).

If treatment is required, spray with Yates Mavrik Chewing & Sucking Insect Killer. It only needs to be sprayed once, but it’s crucial to spray at the right time. Mix Yates Mavrik Chewing & Sucking Insect Killer in a sprayer and apply during early blossom (from pink stage to 20 percent blossom).

The thing to remember is that even if all your prevention methods fail and your fruit is damaged – it is still edible. Apple Dimpling Bug fruit damage does not extend to the flesh of the fruit. You could simply peel off the scarred skin.

What are Apple Dimpling Bugs, &
How to Get Rid of Them

The Apple Dimpling Bug is a member of the bug family Miridae and is sometimes known as the ‘Yellow Mirid’. Bugs of this family are predominantly sap-sucking plant feeders.

Description

Adult Apple Dimpling Bugs are pale yellow-green or greenish-brown insects about 3 mm in length with spines on their hind legs. Male bugs are often slightly darker in body colour than females from the same population. Apple Dimpling Bugs are extremely active insects that are easily startled and will fly off at the slightest disturbance.

Apple Dimpling Bug eggs are kidney-shaped and translucent white in colour.

Nymphs are smaller, wingless versions of the adult bug. The first instar nymphs are initially almost white in colour and as they mature, they gradually become pale to bright yellow.

Life Cycle

Apple Dimpling Bugs develop through a life-cycle of gradual metamorphosis – egg, nymph, adult.

Apple Dimpling Bugs lay their egg singly into the plant tissue leaving only the egg cap exposed, and the eggs hatch after about a week. Apple Dimpling Bugs develop through five nymphal stages before becoming adult bugs. They complete their life-cycle from egg to adult in about three to four weeks.

Female Adult Dimpling Bugs lay about 50 eggs over their lifetime of about two weeks.

Apple Dimpling Bugs (Campylomma liebknechti) complete one generation in apples, then the new generation of adults fly off to other hosts such as various wattles, grevilleas and eucalypts.

The Tasmanian species (Niastama punctaticollis) breeds in Monterey cypress (Cupressus macrocarpa) trees and adult bugs fly in to feed on flowering apple trees (but not breed) at the pink bud stage. This phenomenon occurs where Monterey cypress have been planted around Tasmanian orchards as windbreaks.

apple-dimpling-bug-800x451px-ls-credit-wa-dpird

Image above: adult Apple Dimpling Bug
(Image courtesy of © State of Western Australia
(Department of Primary Industries and Regional Development, WA))

What Plants are Impacted by
Apple Dimpling Bugs

  • Apples (‘Delicious’ and ‘Granny Smith’ varieties are particularly susceptible) and Nashi pears.
  • Cotton (minor pest).
  • Native hosts include wattles, grevillea, leptospermum, eucalypts, and Geraldton wax.
  • Apple Dimpling Bugs also breed in weeds such as Patterson’s curse, medicago, wild turnip, and variegated thistle.
apple-dimpling-bug-damage-800x451px-ls-credit-wa-dpird

Image above: Damage to apple fruitlets caused by Apple Dimpling Bug feeding.
(Image courtesy of © State of Western Australia
(Department of Primary Industries and Regional Development, WA))

Symptoms of
Apple Dimpling Bugs

  • Adult bugs feed on apple buds at the pink bud stage, causing scarring and dimpling as fruits grow. Bugs may later feed on the fruitlets.
  • Affected fruit becomes distorted and unsightly but is still safe to eat.
  • They do no harm to other plant hosts.
apple-dimpling-bug-damage-1-800x451px-credit-denis-crawford

Image above: damage caused by Apple Dimpling Bug
(image courtesy of Denis Crawford)

How to Prevent
Apple Dimpling Bugs
Appearing

Monitor

  • Look for bugs from pink bud stage to petal fall. After that the tree is safe. Try to do this in the cool of the morning, before bugs become too active.

Prevent

  • Control weeds.
  • Use insect exclusion bags on fruit.
  • Try tapping bugs off flowers into a plastic container in the cool of morning and destroy any bugs caught.
  • For out-of-reach flowers, shake the branch to disturb bugs feeding.

Natural Enemies

  • Ants may deter Apple Dimpling Bug.
  • Little else has been published on the natural enemies of Apple Dimpling Bug.

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