Floriculture Sector Biosecurity Guide
Appendix 3: Example of a Pest Fact Sheet for Thrips

Thrips Fact Sheet

Identification

Order: Thysanoptera
Family: Thripidae

Pest species include:
Western Flower Thrips (WFT) – Frankliniella occidentalis
Eastern Flower Thrips – Frankliniella tritici
Onion Thrips – Thrips tabaci
Greenhouse Thrips – Heliothrips haemorrhoidalis
Banded Greenhouse Thrips – Hercinothrips femoralis
Palm Thrips – Parthenothrips dracaenae
Cuban Laurel Thrips – Gynaikothrips ficorum

Life Cycle

Eggs are laid in plant tissue. There are two larval stages (Fig. 1) and two non-feeding stages, the pre-pupa and pupa (Fig. 2), and the adult stage (Fig. 3). Larvae feed on the underside of leaves. The second instar larva drops to the soil to form the pre-pupa and then the pupa. Adults emerge to feed on leaf, bud, fruit, and flowers, depending on species. Most species have males and females; however, the Onion Thrips is parthenogenetic (does not require mating to reproduce). Thrips prefer drier conditions such as along walkways and row ends.

Figure 1. 1st and 2nd Instar Larval WFT
A photo of two instar larva of Western flower thrips on a leaf surface. The first instar larva is smaller than the second instar larva.
Figure 2. Pre-pupa and Pupa of WFT
A photo of a pre-pupa and a pupa of a Western flower thrip on a leaf surface. One is lighter in colour and is a pre-pupa. The other is darker in colour and is a pupa.
Figure 3. Adult WFT
A photo of an adult Western flower thrip on a leaf surface.

Damage

The larvae and adults have "punch and suck" mouthparts that pierce the cell wall and remove the cell contents. The thrips will feed on several cells in a patch before moving to another part of the plant (Fig. 4). They leave behind particle or oily frass, depending on species. Feeding damage results in cell death. In actively growing tissues the killed cells results in deformed growth patterns in leaves, flowers and fruit.

Figure 4. WFT Punch and Suck Patchy Feeding Damage
A photo of Western flower thrip damage from thrips feeding on the leaf.

Monitoring

Larvae: Examine the undersurface of leaves.

Adults: Examine the underside of leaves, flowers (Fig. 5) and fruit, "tapping" a plant over a white sheet of paper, yellow or blue sticky cards in or just above the plant canopy, or trap plants.

Figure 5. WFT Adults in a Flower
A photo of adult Western flower thrip on a flower.

Management

Thrips are very difficult to manage and require constant attention.

Prevention: Install insect screening on vents, quarantine and inspect incoming plant material, dip cuttings with an entomopathogenic fungus where permitted by the label, and pre-emptively release biological control agents.

Reaction: Routinely monitor to determine the number of thrips in the crop so that pesticide sprays can be conducted if the population exceeds the economic threshold or to determine if biological control agents or the pesticide applications have been effective. Trap plants such as yellow marigolds can actively draw thrips out of the crop. Sticky tape can be strung throughout the crop to capture flying adults. Overhead irrigation or water sprays can be used to dislodge thrips from plants.

All images copyright Olds College

Date modified: