Brown-tail moth

Brown tail moth is an insect native to Britain that has hairy black caterpillars with red and white markings. The  urticating (have an irritant effect) hairs can cause breathing difficulties and rashes in contact with skin. 

Brown-tail moth (Euproctis chrysorrhoea) on hawthorn

Quick facts

Common name: Brown-tail moth
Scientific name: Euproctis chrysorrhoea
Plants affected: Rosaceae family including hawthorn, blackthorn, plum, cherry, rose and blackberry
Main symptoms: Foliage is eaten and black hairy caterpillars are present
Most active: April-June

What is brown tail moth?

Brown tail moth adults are white with conspicuous brown hairs on the end of their abdomens. They have a wingspan of approximately 40mm.

The adults are active in July and August and lay batches of 150-250 eggs covered with brown hairs on suitable hosts. These are mainly in the Rosaceae family and include hawthorn, blackthorn, plum, cherry, rose and blackberry.

The caterpillars hatch after about three weeks and begin grazing the foliage and producing webbing. Little damage occurs in late summer as the young caterpillars soon spin dense silk nests (hibernacula) in which they overwinter. These shelters are often in exposed places such as at shoot tips and so are easily seen in the winter, especially as they invariably retain some dead leaves long after the others have fallen.

The caterpillars begin feeding again in April and may cause extensive webbing and defoliation. They are up to 30mm long, blackish with a white band along the sides. The body is covered with brownish hairs and at the rear end of the body there are two raised reddish tubercles. The hairs readily break off and can cause an intense irritation and rash on the skin. In some areas this moth is abundant and sometimes considered a public health problem, although it usually has little impact on the growth of trees and shrubs. Pupation takes place inside silk cocoons on the host plant during June and July.

This moth is found mostly in Southern England and Wales and in some coastal regions further north.

Symptoms

In autumn and winter the most obvious signs of the presence of this moth are the overwintering silk hibernacula which can often be readily seen when deciduous host plants have lost their leaves. In spring and early summer webbing is more extensive and the black and red caterpillars can cause some defoliation.

There are other species of moth that can cause webbing on a range of trees however brown tail moth is the only species which is black with brown hairs and two reddish raised tubercles.

A related species the oak processionary moth has become established in parts of London and some surrounding areas. The caterpillars of this moth also have urticating hairs but it is only found on oak trees. If you find oak processionary moth this should be reported, further details can be found on the Forestry Commissions webpages.

Control

Brown tail moth caterpillars and there larval nests should not be handled without protection due to the covering or irritant (urticating) hairs. For this reason some local councils will take action against this insect.
Check susceptible plants frequently from late summer and into spring, overwintering nests may be obvious during winter moths, so action can be taken if necessary. When choosing control options you can minimise harm to non-target animals by starting with the methods in the non-pesticide control section. If this is not sufficient to reduce the damage to acceptable levels then you may choose to use pesticides. Within this group the shorter persistence pesticides (that are usually certified for organic growing) are likely to be less damaging to non-target wildlife than those with longer persistence and/or systemic action.

Non-pesticide control

  • Provided there is a low risk of contact with the caterpillars hairs where possible tolerate populations of this caterpillar, as butterflies and moths are an important part of the garden ecosystem. Although it can be alarming infested plants will usually survive with only minor checks in growth
  • Encourage predators and other natural enemies in the garden such as birds, hedgehogs and ground beetles
  • Due to the gregarious nature of brown tail moth caterpillars it is sometimes possible to prune out infested shoots. The silk shelters in which they overwinter can be easy to spot after the leaves have fallen. Rubber gloves should be worn to avoid contact with the caterpillars’ irritating hairs.
Pesticide control
If tolerating the presence of these caterpillars or manual removal is not feasible, control may be achieved by spraying with pesticides. Spraying at dusk is likely to give the best results
  • Organic contact insecticides containing natural pyrethrins (e.g. Bug Clear Gun for Fruit & Veg, Neudorff Bug Free Bug and Larvae Killer). Several applications of these short persistence products may be necessary to give good control
  • More persistent contact insecticides include the synthetic pyrethroids lambda-cyhalothrin (e.g. Westland Resolva Bug Killer), deltamethrin (e.g. Provanto Ultimate Fruit & Vegetable Bug Killer, Provanto Sprayday Greenfly Killer) and cypermethrin (e.g. Py Bug Killer)
  • The systemic neonicotinoid insecticide acetamiprid (e.g. Bug Clear Ultra) is also available
Follow label instructions when using pesticides. On edible plants make sure the food plant is listed on the label and follow instructions on maximum number applications, spray interval and harvest interval.
Plants in flower should not be sprayed due to the danger to bees and other pollinating insects.
Inclusion of a pesticide product does not indicate a recommendation or endorsement by RHS Gardening Advice. It is a list of products currently available to the home gardener.

Downloads

Pesticides for gardeners (pdf document)
 


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