Crab spider

The crab spider (Latin: Thomisus onustus) is a member of the Thomisidae family. While these arachnids are primarily predators, they are considered nuisances in professional floriculture and greenhouse management due to the damage they cause to high-value floral products.

This species frequently inhabits flowers, specifically targeting crops like roses, dahlias, and asters. By setting up ambushes for pollinating insects, they physically damage the petals and delicate structures of the bloom. This reduces the quality of the crop and its aesthetic appeal for the final consumer.

The biological cycle of the crab spider is quite adaptive. Females lay their eggs in protective silken cocoons attached to the underside of leaves. After hatching, the juveniles undergo several molts before reaching maturity. They are highly skilled in camouflage, changing their body color to match the petals they occupy, which makes them difficult to detect.

The economic impact of this spider is primarily linked to the degradation of the visual quality of flowers. Beyond physical injury, the presence of these predators on flowers intended for market is often unacceptable to buyers. Furthermore, wounds on petals can act as entry points for various pathogens and mold.

Protection strategies involve integrated pest management practices. Key measures include:

• Regular monitoring of blooms in greenhouses.
• Manual removal of spiders during the early growth stages.
• Controlling prey populations to discourage colonization.
• Using botanical insecticidal soaps if the spider population exceeds thresholds.