The dutiful mother rears up to defend her young, shielding them from a marauding predator and risking her life in the process. No, not a scene from a David Attenborough animal special, but an example of typical insect behaviour in bug species who must pin all their procreative hopes on a single batch of eggs.
These "hero mums of the bug world" ferociously protect their young by fanning their wings and charging predators, according to Prof Douglas W. Tallamy, who reports his findings in the current issue of the journal, Animal Behaviour.
Bug mothers who lay multiple batches are far more likely to hide their young, avoiding guard duty and running from predators, according to the professor of entomology and applied ecology from the University of Delaware. Most insects fall into this category but a few will fight to the death to protect their young.
Semelparous insects which lay a single clutch of eggs staunchly defend their only shot at a genetic legacy, he says. They include the European shield bug, Elasmucha grisea, which will hold its ground and protect its eggs with its shieldlike wing covers, the lace bug, Gargaphia and the praying mantis, Oxyophthalmellus somalicus. About 5,000 of the 25 to 30 million insect species on earth routinely guard their young, Prof Tallamy estimates. "Since these bugs have put all their eggs into one basket, it pays for them to guard that basket well," he said.
And where are the bug dads while the mother risks life and limb to care for her clutch? At the pub, in the air but certainly not caring for his progeny. "Paternal care occurs only among three families of true bugs," he says. Male insects generally have no way of knowing whether they fathered a particular clutch.
Waterbug males are an exception and will repeatedly drip water on their eggs, keeping them moist and healthy. Male Rhinocoris assassin bugs are also co-operative about the babysitting because females usually refuse to mate with males who are not guarding eggs. This proves an inspiration to parental care.