How long should I expect aphid season to last?
Written by
Liu Xiaohui
Reviewed by
Prof. Charles Hartman, Ph.D.The duration of the aphid season varies significantly depending on the climate. Generally, it lasts through the warm months, typically defined as those above 60°F (15 °C). In temperate regions, aphid activity has been shown to intensify from spring through fall. In contrast, tropical areas of the world present a year-round threat from aphids. I use local temperature patterns to monitor and predict aphid outbreaks during the growing season.
Temperate Zones
- Peak activity: April-October (7 months)
- 3-15 generations annually
- Overwinter as eggs during freezing months
Subtropical Regions
- Peak activity: March-November (9 months)
- 10-20 generations annually
- Continuous reproduction above 50°F (10°C)
Tropical Climates
- Year-round activity
- 20-40 generations annually
- No overwintering phase
- Peaks during rainy seasons
Over 60°F, reproduction goes into hyperdrive. Each female produces 80+ offspring each month. New generations are maturing in under 5 days during peak heat. My monitoring began with yellow sticky traps from the very first thaw in spring. Promptly detecting populations can prevent an exponential increase.
Strategies for combating winter depend upon the climate. In temperate areas, aphids produce eggs that can withstand winter conditions by laying them on layers of bark and leaf debris. Populations in the south can last throughout the winter and survive on winter weeds. I make sure to remove any of the plant debris before the first frost. I also apply horticultural oil to kill dormant eggs on trees and shrubs when they are dormant.
Monitoring throughout the year is a solid way to eliminate surprises. You should check your plants weekly throughout the active growing season, and in winter, follow a monthly timeline. I keep a record of infestation dates so I can look for patterns. For instance, I can tell you that in my roses, every year, it seems that the peak pressure of the adults will be late May.
Tailor control strategies seasonally. During spring, biological control methods are necessary. In summer, soap sprays are required. Fall requires cleaning up the garden. Winter requires focusing only on indoor plants, which I change every six weeks, in keeping with the aphids' behavioral patterns throughout the year.
Activity is greatly influenced by humidity. Generally, aphids thrive in humidity levels of around 60-80%. In greenhouses, use vents to help control humidity levels. When spacing plants outdoors, they should have sufficient room to grow and thrive. I always put up rain shelters over my rose plants during rainy or high-humidity seasons. This takes away humidity issues and makes it difficult for them to breed under ideal conditions.
Read the full article: How to Control Aphids: Proven Methods Guide
