Strawberry growers may blame the sap beetle for making small holes in their fruit when it really is the Asian cockroach, a relatively new pest of the crop, say two University of Florida entomologists.
The Asian cockroach has been recognized to remove seeds from strawberry fruit and eat seed contents, say James Price and Curtis Nagle, both based at the university's Gulf Coast Research and Education Center near Balm.
But a handful of registered insecticides can control the pests, they say.
The Asian cockroach was first confirmed in the United States in 1986, when the first species were identified near Lakeland Florida.
A year later, they were found near Brandon and Tampa. Since then, they've spread throughout much of the Southeast.
The Asian cockroach resembles the German cockroach, sometimes called a "water bug," but it flies. It is mostly an outdoor pest and lives in leaf piles and mulch, unlike the indoor American cockroach, also known as a palmetto bug.
In some late-season strawberry plots, the researchers say they've recorded numbers as high as 54,000 per acre.
"Ripe fruit have been appearing on my 2008-2009 UF GCREC strawberry entomology crop for about 2 weeks and I have been finding fruit excavated by the Asian cockroach almost as long," the entomologists wrote in a recent Extension newsletter. "Feeding damage consists of holes in the fruit surface with slightly larger, dry excavations behind the holes.
"The tiniest cockroaches make the small holes, slightly larger than a strawberry seed. Hole sizes range to the largest almost as big as a pencil eraser formed by adults common later in the season. "
Sap beetle feeding holes, on the other hand, are rarely dry and instead quickly become soupy.
Insecticides that contain pyrethrins, such as Pyrenone Crop Spray, Pyganic and Pyreth-It, are registered for cockroach control and are permitted for use on strawberries.
In addition, the pyrethroids Danitol and Brigade are permitted on strawberries and performed very well for Asian cockroach control in spring 2008 GCREC experiments.
Photos and additional information about this insect can be viewed at http://creatures.ifas.ufl.edu.
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