Adults
2.0-3.5 mm long, flat and mussel–shaped, grey to yellowish brown. Found on the bark and fruits of apple trees.
Nymphs (crawlers)
Oval, pale yellowish brown.
Eggs
Minute, oval and white. Deposited beneath the scale.
Other pests with which mussel scale may be confused
- Only mussel scale is mussel-shaped.
- Pear scale and oyster scale individuals sometimes settle on fruits mainly round the calyx, but are roughly circular.