More notes from the wonderful world of ‘How did I not know this stuff was out there?”, aka ‘Wandering around Great Chalfield having fun and learning something new at the same time’.
There hasn’t been enough sun this week to really tempt the season’s insects out from under whatever they crawl below when it gets cold (if they emerge at all that is), but nevertheless what is around is both beautiful and intriguing. What’s very apparent though is just how many ‘wasps’ there seem to be around at the moment.
And ‘seem’ is the operative word, as in fact there is a bewildering array of harmless insects that look – to human eyes, so presumably to a bird’s eye too – like wasps rather than actually being wasps. The obvious explanation is that looking like a wasp confers a benefit: if you’re a fly, for example, that looks like you pack a mean punch you’re less likely to get picked on. On the other hand, being bright does mean being seen by potential predators (by birds, by amateur naturalists etc), so natural selection (driven by whether predators ate bright, wasp-like insects or left them alone) presumably favoured a mimicry strategy over camouflage in a surprising number of cases. In particular many species of hoverflies have evolved to look like stinging hymenopterans, as a stroll along a flower-rich verge or hedgerow in summer will prove.
None of the insects below are wasps, and none can sting us – if you see one, enjoy it, please don’t squash, squish, or otherwise kill it!
Tenthredo temula: a widespread sawfly. Fearsome looking, but absolutely harmless
(unless you’re a plant of course – sawfly larvae are hungry beasts with enormous appetites).
Chrysotoxum cautum: a large hoverfly common in southern/eastern England and coastal Wales.
Beautiful and harmless.
Xanthogramma pedissequum: a small widespread hoverfly (recently split into three very similar species,
but I think this is pedissequum: any other suggestions?). Beautiful and harmless.
Chrysotoxum bicinctum: another widespread hoverfly – this was photographed in August,
but illustrates the point quite well anyway. Like the others, beautiful and harmless.
Nomada marshamella: a very small parasitic ‘nomad’ bee. Like the others,
beautiful and harmless (to us anyway – if you’re a mining bee your larvae could get parasitised).
Wasp Beetle Clytus arietis: a common longhorn beetle that looks very ‘wasp’-like
but like all the species above is beautiful and harmless.
Perhaps it’s because I’m not a trained scientist or anything (and doubtless the answer is online somewhere) but I do wonder when the selection pressure to create all these mimics arose (I’ve never seen a queue of birds lining up to pick hoverflies off a hawthorn for example – but that could just be proof that the strategy works and birds stay away!). And going WAY back into the earth’s history when insects began to evolve I wonder when it was that bees/wasps developed stings, whether flies before that looked like ‘flies’ (there’s presumably no benefit in looking like a bee/wasp that can’t sting and has no toxins in its body), and how quickly natural selection operated to create harmless flies that looked like stinging insects once the latter evolved?
Obviously flies are capable of creating many new generations in a short time, so mimicry could have happened virtually simultaneously, but it’s all a bit ‘chicken and egg’- because another point is that for mimicry to protect you from predators there need to be predators in the first place: maybe the first mimicry evolved to protect flies from insect predators like dragonflies – but how come natural selection didn’t operate to enable early predators to recognise mimics and stop the whole train from gathering speed before it left the station (as it were)?
Hmm, all that just shows what paths a walk in the countryside can lead you down eh…
Photos copyright Charlie Moores/Talking Naturally 2012