Will Freezing Temperatures Kill Scale Insects on Shrubs?

New homeowner in Burleson, TX asks if 80-100 hours of freezing temperatures will eliminate scale insects on shrubs.

Short Answer: No

Freezing temperatures generally do not kill scale insects. Most scale species overwinter as eggs under protective waxy covers, as nymphs (crawlers) in bark crevices, or as mated females—all with cold-hardiness adaptations.

Scale Cold Tolerance

• Armored scales: Very cold-tolerant; survive well below freezing
• Soft scales: Somewhat less tolerant but still survive typical TX freezes
• Population reduction: Extended severe cold may reduce numbers slightly, but rarely provides control

Effective Scale Management

1. Identify the scale species (affects timing/treatment)
2. Dormant oil spray: Late winter, thorough coverage—smothers overwintering stages
3. Crawler sprays: Target mobile nymphs in spring (monitor with sticky tape)
4. Systemic insecticides: Soil-applied imidacloprid/dinotefuran for season-long control
5. Biological control: Encourage lady beetles, parasitic wasps
6. Cultural: Prune heavily infested branches, reduce plant stress

Timing in Texas

• Dormant oil: January-February before bud break
• Crawler emergence: Typically March-April (species-dependent)
• Systemic application: Early spring for uptake before crawler hatch

Don't rely on winter cold. Plan active management for spring.