Environment

Temperature — who benefits from warmth?

Temperature controls metabolism, reproduction speed, and activity. It affects plants first, pests second, and beneficial insects last.

Pests

• Aphids, thrips and spider mites reproduce faster as temperature rises
• Short generation times allow pests to exploit warm spells quickly
• Heat-stressed plants are easier to feed on and defend themselves poorly

Beneficial insects

• Most predators and parasitoids also benefit from warmth
• They require stable temperatures, not rapid swings
• Sharp day–night fluctuations often favour pests first

Warmth helps beneficials only when the system is stable.

Humidity — the quiet deciding factor

Humidity strongly affects survival, stress tolerance and population balance, yet is often overlooked.

Low humidity favours

• Spider mites
• Thrips
• Plant stress and nutrient leakage

Moderate humidity favours

• Predatory mites (Amblyseius)
• Lacewing larvae
• Soil predators such as Atheta

Small improvements in humidity often benefit beneficial insects more than pests.

Light — growth, energy and imbalance

Light drives plant growth first. Insects respond to the plant, not the light itself.

• High light increases growth rate and flushes young tissue
• Flush growth attracts aphids, capsids and thrips
• Nutrient imbalance under high light worsens pest pressure

Light increases insect activity, but without habitat it does not retain beneficials.

Plants — food, shelter and stability

Plants connect everything: environment, pests and beneficial insects.

• Nectar and pollen feed adult predators and parasitoids
• Canopies buffer temperature and humidity
• Structure provides shelter between pest outbreaks

Many beneficial insects cannot survive on prey alone. Without flowering plants, populations collapse between pest cycles.

Habitat structure — where insects live between problems

Beneficial insects spend most of their time waiting, not hunting.

• Edges, margins and refuges act as recovery zones
• Soil structure supports ground predators
• Over-clean systems remove overwintering sites

Structural diversity increases resilience.

Everything is linked

• Environment shapes plants
• Plants shape pests
• Pests feed beneficials
• Beneficials stabilise the system
• Management decisions affect all of the above

You do not manage insects directly — you manage the conditions that decide who wins.