It’s such a good disguise. It looks just like a ladybeetle. If I didn’t catch it actually in flagrante eating the leaves on my squash, I would think it was a good guy.
I was tempted to squash it. Tomorrow I might. But today I thought I might just leave it for the moment and see what happens. There’s only the one that I’ve noticed (though no doubt there are more, just I haven’t seen them yet). It hasn’t done a huge amount of damage, and I’ve got enough squash growing to afford to run the experiment.
What might happen? It could survive. Ladybeetles (the aphid-eating ones and the plant eating ones) have pretty good defences. They can secrete alkaloids that taste really bad, and once a predator has tried it once, the bright orange colour is like a neon sign saying “I taste yuk”.
It could breed, fast, and cause a problem. Many pest species are fast breeders, growing exponentially by a factor of hundreds every week. Lots of beetle sex is their secret weapon in the arms race with their predators. Predators – birds, lizards, frogs, spiders, mantises – are slower to breed. They live longer, breed later, lay fewer eggs. So it takes them a while to catch up.
What’s more likely though, is that a predator will eat it today. If nothing had ever found a way past the defenses, the dominant species on earth would be ladybeetles, not humans. The neon sign strategy could backfire – If I can see it, so can they. A tachinid fly could see it and know, where there’s an adult on the leaf surface, there’s likely to be larvae worth parasitising on the underside. If I had squashed it, that tachinid fly might not have found the larvae, and instead of one 28 spotted ladybeetle I’d have a hundred to deal with.
Hopefully something will thank me for leaving a delicious little spotty morsel for them, maybe feel so well fed they’ll go lay some eggs of their own. But I shall keep a bit of an eye on it just in case.