Day: May 15, 2022

Who has Been in My Strawberries? Slugs and Sap Beetles, Two Common Insect Pests on Strawberries.

Emily Zobel on

By Sankara Ganesh, Maria Cramer, and Kelly Hamby.
Department of Entomology, University of Maryland, College Park

The cool, wet spring weather we have been experiencing favors slugs, so be on the lookout for slug damage. Slug damage may easily be confused for sap beetle feeding, but management of these pests is very different, so it is important to correctly identify the problem. Both pests can be common in matted row production.

Damage: Slug feeding renders fruit unmarketable and susceptible to infestation by other pests including sap beetles. Sap beetle adults are attracted to ripening, ripe, and overripe fruit and directly cause damage through feeding, but may also introduce pathogens and contaminate fruit with larvae. Sap beetles tend to leave behind circular holes while slug damage is often irregularly shaped, and both can cause moderate to deep holes. However, slugs will also feed on leaves and leave behind slime trails.  Monitoring is important to conclusively determine which pest is causing damage.

Figure 1. 1A) Slug feeding on unripe strawberry (K. Hamby). 1B) Slug feeding damage (M. Cramer).
Figure 2. 2A) Sap beetle feeding on strawberry (K. Hamby) 2B. Sap beetle feeding damage (N. Hummel, LSU)

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Two Spotted Spider Mites and Cyclamen Mites Found in Strawberries.

Emily Zobel on

By Jerry Brust, UME

With the cooler weather we have had of late I was surprised to find low levels of mites in strawberry fields, with a few hot spots of mites in some high tunnels. There were two species of mites found: the two spotted spider mite, Tetranychus urticae and the cyclamen mite Phytonemus pallidus.

Fig. 1 Overwintered female two spotted spider mite.

Overwintering female two spotted spider mites are an orangish-red (Fig. 1) and most of the mites that can be seen with a naked eye will appear reddish in color. Spider mites overwinter in the soil or leaf litter, although they may remain somewhat active in high tunnels through the winter. The light yellowish eggs are pearl-like in appearance and are attached to the undersides of leaves or stems. Feeding damage by mites that occurs before fruiting can cause the most loss in yield, but after the first strawberry harvest plants can tolerate much greater rates of infestation. Growers should check their strawberries for mites now, especially if you have them in a high tunnel. If mites are found now you need more than 5 mites per leaflet (1/3 of a leaf) to justify the expense of a miticide application.

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