Myrmecoris gracilis (36)
|Lesser known residents of my backyard:|
It was an exciting discovery to me . Ever since I had bought the book on bugs I was hoping to find those small Ant imitating bugs. Finally I detected some larvae in my own backyard! The picture shows a 4 mm long Ant mimic bug (Heteroptera; Miridae; Myrmecoris gracilis (R. Sahlberg, 1848); Ameisenwanze). It is patrolling in an Aphid colony on Galea and sucking out a freshly hatched Neuropteran larva. It's a "first" on TN. A second picture can be found in the WS section.
What is the masquerade of this bug all about? Ants are known to protect aphids from predators like Coccinellid larvae or adults and from Syrphid larvae; by tickling the aphids with their antennae the ants get their reward for patrolling in the form of sugary droplets. Ants are in turn protected from predators through formic acid release. They signal to potential predators the fact of being an ant with the typical body shape. From what I saw the Ant-like bug royally ignores the rules of politeness in the Aphid-predator-Ant system and eats aphids and their predators alike: the ant costume makes it a "Wolf in sheepskin".
ID: First you have a hard time to distinguish the bug from ants (that might be the reason Linné did'nt describe them). Then I had to go by the pictures in the excellent book of E. Wachmann et al. 2004. Wanzen Bd. 2. Goecke& Evers, Keltern D. There is no other similar bug species in Europe. The adults are apterous like the larvae. The species is found in Middle and Northern Europe and East to Siberia and Korea. In the Alps it is found up to 2'000 m a.s.l. There is one generation per year. Eggs are deposited inside old grass stems where they overwinter.