Strawberry blossom weevil
Strawberry flower beetles appear in spring from soil temperatures of 10-14 °C. The beetles feed on petals of strawberry and various ruderal plants.
The females bore a hole in the flower bud with their proboscis, in which they lay one or more eggs, depending on the flower size. The beetles then gnaw the bud stalk, the upper part of which folds over and dries up, causing the bud to fall to the ground. After six to eight days, the beetle larvae hatch, develop further in the bud, and pupate after ten to 14 days. The pupal stage lasts about one week. In June/July, the young beetle appears, causing insignificant feeding damage to the leaves, and moves into winter hiding in the soil or under plant debris in August. The strawberry blossom weevil produces only one generation per year.
Individual flower stems are gnawed and snapped off or bitten through. The flower buds above the damaged area dry out and fall to the ground (determined by visual inspection).
If entire inflorescence stems are damaged, it is the strawberry stem borer(Coenorhinus germanicus).
The damage pattern could also be caused by the Union quarantine pests Anthonomus bisignifer (Japanese strawberry blossom engraver) and Anthonomus signatus, which have not yet appeared in Europe.
Prevention and control
- Treatment of the plants with plant protection products approved for this purpose (see list of plant protection products approved in Austria).
- immediately after reaching the damage threshold. The damage threshold for treatment measures is the first appearance of bent flower stems or 1 adult beetle/100m².
- In the hobby garden, flower buds lying on the ground or destroyed can be collected and destroyed as a direct measure
Lethmayer, C., Hausdorf, H., Blümel, S., 2004. The first field experiences with sex aggregation pheromones of the strawberry blossom weevil, Anthonomus rubi, in Austria. IOBC/WPRS Bulletin, 27(4), 133-141.
Blümel, S., 1989. the strawberry blossom weevil - interesting facts about biology and control. Better Fruit, 34(5), 127-129.
Last updated: 25.05.2023