[Ecological effect of the social behavior in two Elasmucha species (Heteroptera: Insecta)]

In Elasmucha grisea and E. fieberi we have confirmed parental care with a high effectiveness; in E. fieberi this behavior was still unknown. Two years of investigations revealed that a loss in the progeny was diminished during the egg stage by the defence behavior of the female, in 1972 from 92% to 9% and in 1974 from 81% to 4%. Because the 9% and 4% are not caused by external influences that can be eliminated by parental care, the effect of the defence behavior of the female amounts to about 100%. The eggs are particularly protected against entomophageous arthropods. Defence behavior against the male is not present. The female possesses no fungeous protection for the eggs, or if it does it is insignificant in view of the great threat posed by predators. No differences in social behavior between E. grisea and E. fieberi could be demonstrated.