Mother love is something we take for granted among ourselves but it is not universal in the animal kingdom, and nor is it easy to predict which kinds of animals will look after their young and which won’t. Most mammals, from whales to humans to mice, do; most birds do; most reptiles don’t, but crocodiles do; most spiders don’t but some, e.g. the Wolf spider, carry their babies around on their backs (see, too, Mummy Long-legs); and most insects apart from the social insects (ants, wasps, bees and termites) don’t.
Parental care has been seen in only a few hundred non-social insect species out of about 20 million. Some of our shield bugs are in that minority. About a year ago I photographed an adult on a fern frond and only noticed the smooth whitish shape of an egg beneath … her, I realised … after I saw the image on screen. She was just under the edge of my carport so I went out next morning and saw the neat array of eggs nestled between her hind legs.
Seeing her guarding the eggs like that was a surprise but, even more surprisingly, she stayed with the eggs until they hatched a week later and with the nymphs (babies) for another few days yet. The eggs hatched on a Saturday, and mother and babies stayed together in the same spot until the Tuesday afternoon. Then Mum left, and the babies gradually dispersed over the next day or two.
That was at the end of July last year but it was not an isolated incident. I was reminded of it when I saw another mother standing protectively over her babies in August this year, and there are similar examples on Flickr’s Field Guide to Insects of Australia group and here on the Brisbane Insects site.
Interestingly, all of them feature the species in my photographs or a close relation, Poecilometis sp. (Hemiptera, Pentatomidae). They don’t appear to have any common name more specific than ‘stink bug’ (for the foul-smelling liquid they exude in defence) or ‘shield bug’ (for their shape).
The colourful Harlequin Hibiscus Bug (not my photo) is the only other Australian sap-sucker I know to show any care for its progeny. The mother will guard the eggs, but I don’t know whether she stays with the nymphs after they hatch.
Searching Flickr for ‘Hemiptera’ plus ‘eggs’ will find you many more pictures of adult insects (worldwide) with eggs but it is not always clear whether they are just laying them or protecting them afterwards.
A slightly shorter version of this post appeared in Kapok, newsletter of Coastal Dry Tropics Landcare, Inc., in September 2011.