Pyrrhocoris apterus

Lore & Background

The firebug generally mates in April and May, with copulation lasting from 12 hours up to 7 days, proposed as a form of ejaculate-guarding under high male competition. Its diet consists primarily of seeds from lime trees and mallows, and it is frequently observed in aggregations of tens to perhaps a hundred individuals, especially in immature forms, near the base of lime tree trunks on the sunny side.

Reader's Guide

P. apterus gained unexpected significance in the 1960s when researchers who had reared the bugs for ten years in Prague, Czech Republic, attempted to do the same at Harvard University in the United States. After the fifth nymphal instar, instead of developing into adults, the bugs entered a sixth instar stage or became adults with nymphal characteristics; some sixth instars went on to a seventh instar, but all died without reaching maturity. The cause was traced to paper towels made in America, with the effect replicable using American newspapers such as the New York Times but not European newspapers such as The Times. The active agent was a hormone found in the native balsam fir tree (Abies balsamea) and some other North American conifers, used in paper manufacturing. The most potent chemical component was later identified as juvabione, the methyl ester of todomatuic acid, produced by trees in response to wounding; it mimics juvenile hormone closely, defending against vulnerable pests. This discovery highlighted the diversification of hormone receptors in insects, as the effect was specific to P. apterus and not other insect species.

Did You Know?

• The firebug's long copulation duration, from 12 hours up to 7 days, is proposed as a form of ejaculate-guarding under high male competition.
• In the 1960s, paper towels made from balsam fir pulp caused firebugs to fail to mature, entering extra nymphal instars instead of becoming adults.
• The chemical juvabione, found in balsam fir trees, mimics juvenile hormone and was the cause of the developmental disruption.
• The effect was due to the tree species used in the paper; European papers from other trees lacked the compound, so they did not produce the same result.