Earlier this spring, an observant citizen in the Sugarhouse area of Salt Lake City noticed brightly colored insects in his back yard. He questioned Christy Bills, Entomology Collections Manager at the Utah Museum of Natural History, about these bugs. She had never seen them before and therefore took specimens to the Utah Department of Agriculture and Food for a positive identification. In May 2008, they were confirmed as Pyrrhocoris apterus (Heteroptera: Pyrrhocoridae) by Tom Henry, a national specialist at USDA-APHIS. Pyrrhocoris apterus, also known as the red fire bug, was not known to occur in North America until now.
Because the red fire bug is a new record in North America, much of the life history is unknown and must be extrapolated from European publications. Red fire bugs are native to central Europe, but are also found in western Siberia, southwestern Mongolia, India, and northwestern China. In their native range, red fire bugs feed on seeds from a wide range of plants. Like all true bugs, they have a piercing sucking stylet that removes fluid. The most common host plant family is Malvaceae which includes mallow and linden. Some reports of cannibalism and predation on other insects have also been reported.
As with all true bugs, red fire bugs go through simple metamorphosis (egg, nymph, adult). Typically they have one generation per year, and the adults are the overwintering life stage. In the spring, females lay eggs that hatch into small, red nymphs that resemble boxelder bugs. Red fire bug adults are 0.25-0.5 inches in length, and in general the females are slightly longer and wider. The forewings are variable in size, ranging from shortened to absent. The most common form in Utah is the shortened wing adult. The forewing color pattern is also highly variable when present, but is generally red with black spots. The wings cross over the back and are held flat against the body at rest.
So far, no one can explain how the red fire bugs were introduced into the Salt Lake City area, but likely were brought in on host plant material. These bugs have similar behaviors to boxelder bugs in that they like to congregate under leaf litter or sun themselves on structures. I do not expect the red fire bug to become a significant economic problem, but it will probably be considered another nuisance pest for homeowners. If you suspect red fire bugs in your area, please collect specimens or take pictures for the Utah Plant Pest Diagnostic Laboratory. We would greatly appreciate knowing more about the distribution in Utah and other observations you may have about this new insect.
For more detailed information, click here for the red fire bugs fact sheet located on the UTAH PESTS Web site.
-Erin Hodgson, Extension Entomologist (No longer at USU)