Spider Mites on Rex Begonia
Rex Begonia (Begonia rex)
Symptoms
- fine webbing between leaves
- stippled dots on foliage
- dull or bronzed patches
- the leaf's patterned coloring looking flatter and less vivid than usual
Causes
Spider mite infestation
Mites feed by puncturing individual cells on the leaf surface and draining their contents, leaving small pale flecks scattered across the tissue. Rex Begonia's dense, swirling silver and maroon pattern gives that early feeding damage plenty of visual cover, so a light infestation often reads as part of the leaf's natural marbling until webbing appears and makes the problem unmistakable.
Drier microclimates within an otherwise humid setup
Even in a generally humid growing space, spots with reduced airflow to the humid air source, or periods when a terrarium or dome is opened for ventilation, can create localized drier conditions that favor mite reproduction, since mites thrive specifically in lower ambient moisture around the leaf surface.
Introduction from a new plant or shared growing space
Mites travel easily between plants sharing a terrarium, humidity dome, or close grouping, meaning one infested plant introduced into a shared space can spread mites to several others within days.
How to Fix It
- 1
Confirm the diagnosis by holding a white sheet of paper under a leaf and tapping gently — if tiny specks fall and begin moving, spider mites are present.
- 2
Isolate the plant immediately from any shared growing space, since mites spread quickly between nearby plants.
- 3
Rinse the plant gently under lukewarm running water, taking care with the delicate leaves, to physically remove a large portion of the mites and webbing.
- 4
Apply a light insecticidal soap spray, testing on one leaf first given this species' sensitivity, coating leaf undersides where mites concentrate.
- 5
Repeat treatment every four to five days for at least three rounds, since mite eggs are resistant to most treatments and hatch on a staggered schedule.
- 6
Maintain consistently high humidity throughout the growing space once treatment is underway, since stable, adequate moisture slows mite reproduction significantly compared with fluctuating or locally dry conditions.
Prevention
- Maintain consistent, adequate humidity throughout the growing space, avoiding localized dry spots
- Inspect new plants closely before introducing them to a shared terrarium or humidity dome
- Check leaf undersides regularly against a light source to spot early stippling against the plant's natural pattern
- Ensure some airflow even in enclosed humid setups, since airflow combined with humidity control helps limit several pest types at once
- Quarantine any plant showing early pest signs immediately rather than waiting to confirm a full infestation
Quick Summary
| Plant | Rex Begonia (Begonia rex) |
|---|---|
| Category | Pests |
| Likely causes | Spider mite infestation, Drier microclimates within an otherwise humid setup, Introduction from a new plant or shared growing space |
| Fix steps | 6 steps — see above |