Strawberries: Fruit is small, seedy, and has a bronze cast (thrips)

Thrips are very small insects that feed on pollen and developing fruit, causing small, seedy berries, bronzing between achenes, and occasionally cracked fruit.

 

The immature thrip cannot fly. Adult thrips have wings and can fly or move in air currents for long distances.

A pale beige insect with two red eyes, stubby straight antenna, and a fat body with 19 segments that look like shallow grooves.
Enlarged photo of immature thrip.

Since thrips hide within flowers, gently blowing on the flowers will cause thrips to emerge in response to carbon dioxide. More than 10 thrips per flower can cause economic damage.

Thrip feeding on fruit causes net-like russeting as they injure the surface of fruit. Cat-facing may also occur.

Following photos are courtesy of Kathleen Demchak, Penn State University.

Extreme close-up of a yellowish insect with a long, pointy abdomen. The insect is sitting on strawberry fruit skin on strawberry beside a strawberry seed. The seed is twice as big as the insect.
Mature thrip feeding on ripe strawberry.
Close-up of a yellow insect with straight antenna standing on the surface of a ripe strawberry. Surface looks slimy as thrip has eaten the top layer of strawberry flesh.
Mature thrip feeding on ripe strawberry.
Close-up of strawberry skin with four seeds in frame. The skin is mottled by uneven, lacy patches of bronzing.
Detail of russeting on immature strawberry.

Unripe strawberry fruit growing on plant. Fruits appear to be in green and pink stage of ripening, but instead have a bronze color. Bronze color is most prominent in skin surrounding seeds.

More thrips information:

Use these resources if you need additional help with diagnosis and to find solutions to your problem.