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28 Spotted Ladybeetle

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.

{ 11 comments… add one }
  • Gillian December 21, 2011, 11:37 am

    I have always wondered if anyone goes around counting the spots on their ladybeetles. When I see one I think “oh I should count the spots and see if it is a goodie or a baddie”, but I normally get waylaid. so I guess I do the same thing as you are doing, just not as scientifically 😉

  • Elaine December 21, 2011, 12:21 pm

    I see this as a new calling – Ladybeetle-spot-counter! 🙂 There’s a “26-spot” as well, so someone must have counted them at one time. Some folks just don’t have enough to do 😉 The ‘good’ ones have many less spots and there’s no confusion really once you’ve seen a few of the other ones (the Aphid-eating ones). There’s a good site for ‘Brisbane Insects’ and it would cover a greater area than just Brisbane, probably down to your way Linda so it might be useful for you. http://www.brisbaneinsects.com/ and they have a Ladybird field-guide which is very good especially if you could print it in colour and laminate it, something to have on hand. It’s a very fine site for a lot of IDs and just seeing the breadth of photographs the family has taken over the years is well worth some time even if the readers live well outside of Briz.

  • Linda December 21, 2011, 12:31 pm

    The ladybird field guide is great!

  • Melania December 21, 2011, 4:10 pm

    Hi! I went to a friend’s house the other day (only a suburb or two over, in inner city Brisbane) and noticed a many spotted lady beetle or two. I brought it inside on a leaf and asked my husband to count it while I kept preparing food!! It happened to be a 26 or 28er. Will be interesting to see what happens in their garden. Hopefully not too much damage to their vege garden.

  • Johanna December 22, 2011, 4:55 am

    Thanks Lindy, I have a few of the 26 spotters on my potato plant, which has not been looking that well since their arrival. I thought they were good guys too.

  • celia December 22, 2011, 7:31 am

    That’s cheating, masquerading as a ladybeetle. I wonder if there’s someone we can complain to.. 😉

    I have yellow ones like that on my cucumber leaves, but Pete insists that they’re ok, and someone on Gardening Australia said they were keeping the mites under control. I have no idea, but we are getting cukes this year, so I’m not complaining.

    Oh, and other good news…we have ONE zucchini!! Surely there is never JUST one? 🙂

  • Linda December 22, 2011, 8:51 am

    Hi Celia, some of the yellow ones are fungus eaters, which means they keep powdery mildew under control. The 26 and 28 spotters are the only bad guys. And, like most pests, if they are actually out of control and doing real damage, they are probably the least of your worries.

  • Jason Dingley December 30, 2011, 5:21 pm

    Fascinating about how the neon sign strategy backfiring and giving away the larvae whereabouts to the tachinid fly. Goes to show sometimes a gardener is better to not react to quickly.

  • Kirsty@BowerbirdBlue January 3, 2012, 10:35 pm

    hmmm, think I’d have given it the squish. I’ve got a few bugs in my garden that no one seems keen on – cherry slugs and 3 lined potato beetles – I think we’re their only predators.

  • celia January 31, 2012, 5:49 pm

    Linda, just popped back to this post to look at the photo – yep, that’s what’s been doing damage to our old lebanese cucumber. We’ve been out squashing them today – they seem to like the wet humid weather and there were quite a lot of them to get. We have lots of the yellow fungus eating ladybirds though, which is also good.

    It’s interesting how the beds which have the chooks rotating through them seem to do so much better plant-wise than the other ones, even though we heavily mulch and fertilise the non-chook beds with blood and bone!

  • Deb April 2, 2014, 4:16 pm

    Hi, my Zucc’s have just been destroyed by this critter, my google research has shown it to be a Squash lady beetle, and it is unfortunately a baddie. It has yellow larve with tiny black spikes on them (grain of rice size) that take over the plant. Organic advice to get rid of it is to pick them off by hand and squash them before they take over.

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