Adult female
Body oval, about 0.4 mm long, strongly convex and a dark red colour. The body is furnished with long setae arising from light coloured pinacula. These whitish spots at the base of the setae are diagnostic for this species.
Adult male
Similar in general appearance to female but smaller, yellow green to bright red and more or less pear-shaped, tapering posteriorly.
Immature stages
Pale yellowish-green to bright red. The first stage larvae has 6 legs
Eggs
Red, roughly spherical, 0.1 mm diameter, with the top drawn to a thin spike Overwintering eggs found on bark (guyed to the bark with threads of silken webbing) in winter and early spring, or on the undersides of leaves during summer.
Other pests or arthropods with which fruit tree red spider mite may be confused
Two-spotted spider mite
The two-spotted spider mite, Tetranychus urticae, is a generally abundant spider mite species which has a very wide host range and does occur on apple and pear trees especially in hot summers.
- High populations do not usually develop on apple or pear.
- The female is a green colour with two dark patches on the sides of the body.
- It causes similar damage to the fruit tree red spider mite.
Bryobia mites
The apple and pear bryobia mite, Bryobia rubrioculus, is superficially similar to the fruit tree red spider mite but is uncommon on sprayed fruit trees.
- Female bryobia mites have spatulate setae on their backs.
Tydeiid mites
The tydeiid mite, Tydeus californicus, commonly occurs in small numbers on the undersides of apple leaves usually near the main vein.
- It is smaller than fruit tree red spider mite and has a greenish yellow colour and does not cause significant damage.
- It provides an alternative food source for the orchard predatory mite Typhlodromus pyri.
Apple rust mite
The apple rust mite, Aculus schlechtendali, causes bronzing damage to the foliage of apple trees similar to that caused by fruit tree red spider mite but the rust mite is much smaller, light brown in colour and wedge-shaped.
- The rust mite and fruit tree red spider mite often occur in high numbers together because their key natural enemy, the orchard predatory mite Typhlodromus pyri, is absent.