Parent bug

This is the first parent bug I've seen since the previous generation began to come out of hibernation, back in the spring. Each summer I hope to get the chance to observe this bug's unusual breeding behaviour, but I haven't managed it yet - which is disappointing but not really surprising, because in our garden it most probably happens high up in our birch trees.

After the overwintered adults emerge in the spring they mate, and the males die soon afterwards. Each mated female lays a tight cluster of eggs on the underside of a birch or alder leaf, and stands guard over them until they've hatched, and the first instar nymphs have eaten their egg cases. If any try to move away she will touch them with her antennae to encourage them back into the brood.

During the second and third instar stages the nymphs move to nearby leaves and catkins to eat, but their mother continues to shepherd them together for as long as she can. If two or more females are brooding close together, they sometimes share the care of their offspring in a kind of crèche. After the third moult the nymphs become independent and their mother abandons them, but up until then she will protect them from potential predators such as earwigs and ants by tilting towards them, flapping her wings, and releasing noxious smelling fluid from her scent glands.

The parent bug is a member of the family called the Acanthosomatidae, which also includes the birch, hawthorn and juniper shieldbugs. The hawthorn shieldbug can be as big as 1.5cm in length, but birch and juniper bugs average around 1cm, and the parent bug is smaller still at 7-9mm, the male being appreciably smaller than the female. I beat this individual from a hazel tree, along with a couple of green shieldbugs which were so much bigger - around twice the length and twice the width - and so much more brightly coloured, that I almost failed to spot the parent bug in the tray.