When do mites appear on trees? - briefly
Mite activity on trees usually starts in early spring, when buds open and temperatures exceed about 10 °C (50 °F). Populations reach their highest levels from late spring through early summer before natural predators curb their numbers.
When do mites appear on trees? - in detail
Mite activity on woody plants follows a seasonal pattern driven by temperature, humidity, and host‑tree phenology.
In spring, as temperatures rise above 10 °C (50 °F) and buds break, many eriophyid and spider mite species emerge from overwintering sites in bark crevices, leaf litter, or protected leaf folds. The first generation often appears in conjunction with leaf expansion, exploiting the tender tissue for feeding and reproduction.
Summer brings the peak of population growth. Daily temperatures between 20 °C and 30 °C (68 °F–86 °F) accelerate mite development cycles, shortening egg‑to‑adult intervals to 5–7 days for fast‑reproducing species. High relative humidity (60–80 %) supports egg viability, while low humidity can increase mortality. Under optimal conditions, multiple overlapping generations can occur, leading to noticeable infestations on foliage and shoots.
Autumn signals a gradual decline. Cooling temperatures below 15 °C (59 °F) lengthen developmental times, and reduced daylight curtails feeding activity. Many species migrate to protected overwintering habitats—under bark, in bud scales, or within leaf litter—where they remain dormant until the following spring.
Winter generally sees minimal external activity. Mites persist in sheltered microhabitats, surviving low temperatures as diapause stages. Occasional mild spells may trigger limited activity, but population expansion remains suppressed until spring warming resumes.
Key factors influencing timing:
- Temperature thresholds: 10 °C for emergence; 20–30 °C for rapid reproduction.
- Humidity range: 60–80 % optimal for egg survival.
- Host phenology: bud break and leaf expansion provide initial food sources.
- Overwintering sites: bark crevices, bud scales, leaf litter maintain populations during cold periods.
Understanding these temporal dynamics enables precise monitoring and timely intervention to mitigate mite damage on trees.