Updated 02/19/10

Eric H. LaGasa, Chief Entomologist - WSDA, Olympia

Background / Situation Update

Figure 1. Rhyparochromis Seed-bug, Rhyparochromis vulgaris Figure 2. Raglius Seed-bug, Raglius alboacuminatus Figure 3. Rhyparochromis Seed-bugs on Home Foundation.

Since the discovery of an introduced, exotic seed-bug (Figure 1) by a homeowner in Orting (Pierce Co.) in 2001, populations of this species have steadily spread and increased. Large numbers have been reported from areas from King County south to Lewis County in the fall and spring.

In 2005, a second introduced exotic seed-bug species (Figure 2) was found in Western Washington. This slightly smaller, similar version of the first, is also being reported from King County as well as in areas north to Whatcom County.

Large numbers of the seed-bugs may occur in and around homes and other buildings in the fall as they seek out protected places for over-wintering, and again in the spring as they leave shelter to disperse.

Both species are native to continental Europe, where they are a periodic nuisance but not considered damaging plant pests. The smaller of the two species (Raglius seed-bug) has also been found in California and Utah, where alarmingly high initial populations have declined in subsequent years.

Here, the Orting homeowner who first reported the Rhyparochromis seed-bug problem in the fall of 2001 has noticed a significant decline of the bugs in her area in the last two years.

Often, the first place homeowners notice the presence of the seed-bugs is around home foundations and on exterior walls (Figure 3). The small, dark bugs are very rapid runners, often mistaken for small beetles, and can fly. Unlike many native true bugs, they don't have a strong odor. If control of nuisance populations is necessary, contact WSU Extension Service for recommendations.

(Rhyparochromis = Rye-pair-o-chrome-iss, Raglius = Rag-lee-us)

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Distribution / Usage Note -This report is provided as a public resource for the detection and identification of insect pests described. This entire document, as well as individual graphic images, may be freely copied, distributed, and used in electronic and printed format as long as they are not modified for content or used for commercial purposes. Eric LaGasa, Chief Entomologist, Pest Program / Plant Protection Division, Washington State Department of Agriculture,  P.O. Box 42560, Olympia, Washington  98504-2560,  (360) 902-2063  PestProgram@agr.wa.gov Inquiries regarding availability of this publication in alternative formats should be directed to the WSDA Receptionist at (360) 902-1976.