Lepidosaphes ulmi

Apple mussel scale
File:Lepidosaphes ulmi.jpg
Scientific classification Edit this classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hemiptera
Suborder:	Sternorrhyncha
Family:	Diaspididae
Genus:	Lepidosaphes
Species:	L. ulmi
Binomial name
Lepidosaphes ulmi (Linnaeus, 1758)

File:Lepidosaphes ulmi 180721.jpg

Lepidosaphes ulmi on Ceanothus in England

Lepidosaphes ulmi also known as apple mussel scale or oystershell scale is a widely invasive scale insect that is a pest of trees and woody plants. The small insects attach themselves to bark and cause injury by sucking the tree's sap; this metabolic drain on the plant may kill a branch or the entire tree.

Host plants

Over one hundred and fifty host plant species are known for the oystershell scale including members of the families Aceraceae, Betulaceae, Caprifoliaceae, Celastraceae, Elaeagnaceae, Grossulariaceae, Hydrangeaceae, Juglandaceae, Oleaceae, Pyrolaceae, Rosaceae, Salicaceae and Tiliaceae. Apart from forest trees and ornamentals, the oystershell scale is a pest of apples, pears, plums, peaches, apricots, mulberries and currants. It infests trunks and branches and is also found on leaves. Heavy infestations can kill branches and even cause trees to die.

Control

The crawlers are vulnerable to a number of pesticides but adult oystershell scales are protected by their waxy scales which repel water. Use of horticultural oils may overcome this problem but control is still difficult. In gardens, trunks and branches may be scrubbed and heavily infested wood pruned out and removed. In some parts of the world, populations are controlled to a certain extent by the oystershell scale parasitoid, Aphytis mytilaspidis and the ladybird Chilocorus bipustulatus.