We learn as small children that things that fly and are striped yellow and black are to be avoided as they sting! As we get older we learn this is not always true, but we are still wary.
Is that a wasp?
We are not the only ones who can read these warning signs, birds, mammals, and insect predators all recognise that if something is striped black and yellow* it is to be avoided as it may sting or be poisonous to eat.
But why? How has this come about?
Obviously being able to defend yourself is an advantage, but if the predator only realises you can sting or are toxic after you have been attacked and damaged then it’s not much use.
You must advertise that you can defend yourself before you are attacked, and the clearer and brighter the markings the better, so yellow and black is perfect.
But now things get more complicated. It costs the insect a lot of energy to make toxins or to equip itself to sting. Instead, many insects take the cheaper option. They have yellow and black markings, but they are completely harmless, protected by deceit.
The most successful mimics are those that most closely resemble the insect they are copying; some are very good indeed. Some copy not just the way an insect looks but also how it flies and the way it holds its wings.
The hornet hoverfly (Volucella zonaria) is so good it fools even the hornets, entering their nest to lay its eggs. The larvae then live in the nest protected by their predatory hosts as they scavenge debris.
Other species are poor mimics and it’s not always clear which species they are mimicking. It is even possible these are copying a species that no longer lives in the UK. Entomologists don’t regularly nibble insects(!) so some may not be mimics at all but are themselves poisonous or distasteful. As always, there is more research to be done.
So, keep your eyes out for striped invertebrates. You will be surprised how many there are and the variety in their form and lifestyle.
Even if an insect can sting (and most cannot) they won’t sting you unless they are threatened by you. Keep calm, move slowly, avoid going near their nests or getting very close and even wasps and hornets will ignore you.
As for me, no way I will ignore these fascinating creatures that play such an important part in the web of life that keeps us all alive.
(Volunteer recorder for BBOWT, focusing on entomology)
*Orange/red and black are other warning combinations and here too there are both toxic insects and their mimics. It is not just insects that use these colours, fish, amphibians and reptiles too.