What does a spider mite look like on fir trees? - briefly
Spider mites on firs appear as minute, often reddish‑brown or pale yellow specks, usually 0.2–0.5 mm long, clustered on the undersides of needles and surrounded by fine silk webbing. Their presence is indicated by stippled or bronze‑colored foliage and a dusty web covering.
What does a spider mite look like on fir trees? - in detail
Spider mites that infest fir trees are microscopic arachnids, typically measuring 0.2–0.5 mm in length. Their bodies are oval‑shaped and lack visible segmentation, giving a smooth appearance under low magnification. The dorsal surface is usually pale green to yellow‑white, sometimes with a faint reddish tint, while the ventral side appears slightly darker. Legs are extremely short, often invisible without a microscope, and the legs end in tiny claws that cling to needle bases.
Key visual indicators on the host include:
- Webbing: Fine, silvery strands covering the undersides of needles or forming a cobweb-like mat at branch tips.
- Discoloration: Needle tips turn yellow, bronze, or stippled with tiny pale spots where mites feed.
- Drop‑off: Small, water‑filled sacs (exuviae) detach from the mite’s cuticle and fall to the ground, resembling dust.
- Stippling: Minute, pinpoint lesions appear on needle surfaces, visible when the foliage is held up to light.
Population density can be inferred from the density of webbing and the extent of stippling. A heavy infestation often results in needle loss, thinning of the canopy, and reduced growth rates. Detection requires a hand lens or a low‑power microscope, focusing on the underside of needles where mites reside and lay eggs.