about this blog



This blog tracks the ongoing changes of my garden, and the wildlife I try to attract to it. It's a nature blog. It contains my thoughts and musings about anything and everything to do with nature - gardening, book reviews, philosophy, travel, science, history, art, design, politics.
Catmint is my signature plant because it has all the qualities I value in a plant: resilience, beauty and the capacity to spread prolifically . Unfortunately it's not indigenous. If I was starting again I'd probably choose an indigenous plant.

Monday, 4 November 2013

who ate the aphids? a catmint garden mystery
















The garden seemed full of aphids. I did nothing, just watched curiously. The aphids went away. The plants recovered.

Who ate the aphids?

It wasn't me, the omnivorous human. People do eat insects, like witchetty grubs and chocolate ants. The grubs I've seen in the garden aren't witchetty grubs. They're a dirty unappetizing grey colour.  I definitely haven't eaten any, and I prefer my chocolate ant-free.

So who did eat the aphids?

It wasn't the ring-tailed possum occupying the nesting box high up in a gum tree. These marsupials eat leaves, blossoms and fruit. They don't eat aphids.


So who did eat the aphids?

It wasn't the Australian Painted Lady butterfly (Vanessa kershawi). During its larval stage it eats leaves. As an adult butterfly it feeds on nectar from flowers. It doesn't eat aphids.



So who did eat the aphids?

It wasn't the bee. Bees are vegetarians. Their diet consists of pollen, nectar and water. They don't eat aphids.


So who did eat the aphids?

Large number of,  syrphid flies, or hoverflies, have been observed in the area this spring. They look like bees, but they're actually flies. (Flies have one pair of wings, bees have two). Adult hoverflies only eat nectar and pollen, so it wasn't them. But hoverfly maggots are known to be so fond of aphids, they are used as a biological control. The mystery is solved, but ...



Did anyone else eat the aphids?


When I enlarged the photo below, to my surprise I saw other insects that enjoy eating aphids. Looks like there is more biodiversity in the garden than I realized.

In the photo below, on the bottom lefthand side, you can see a Green lacewing (Mallada signata). The larva of these insects are predators of a wide range of insects, including aphids.


In the photo below, the top of the stalk, underneath the top leaves, you can see a tiny white mite, and a few more more blurry ones below. These are likely to be predatory mites. Predatory mites eat garden pests like spider mites and aphids.


Following is a video showing predatory mites close up and personal.



















Did anyone else eat the aphids?

This unidentified tiny spider probably belongs to the large group of Australian orb weaving spiders, consisting of more than one hundred species. It certainly eats insects, so any flying aphids would be dead meat if they ventured too near. Some aphids have wings, which they use to fly to the next food plant to start a new infestation.  I don't think they fly far and I've never seen aphids caught in a spider web. So I don't think this spider eats aphids.



So the mystery is solved. The aphids were eaten by beneficial insects: predatory mites and the larvae of hoverflies and lacewings.  

40 comments:

  1. In my neck o' the world, Monarch caterpillars eat the aphids. Along with the leaves. They can defoliate a milkweed plant pretty quick. What time of year is canary island wormwood planted?

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    1. Hi Linda, Shame you can't train them to stop at the aphids, but I guess Monarchs need a lot of nutrition for their long journeys. Autumn is always the best time to plant, but unless it's very hot, round here we can plant most of the year.

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  2. Interesting post and beautiful pictures. We have many ladybugs to eat the aphids.

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    1. Hi Janneke, I know ladybugs are wonderful aphid-eaters. I see them in other gardens, but they haven't been seen in mine for at least 10 years.

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  3. Thank you for that information! I didn't know there were so many insects that would eat aphids. Really only Lady Bugs came to my mind. But my recently planted Butterfly Weed plants had been covered in aphids so it was interesting to read the above comment that Monarch caterpillars also eat aphids. Hopefully we will have some Monarch butterflies around next year!

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    1. Dear Dorothy, I hope the monarchs eat your aphids, but don't eat all the leaves as well!

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  4. Sometimes it's hard not to interfere when precious plants are under attack. But your 'doing nothing' method is probably the wisest method. Eventually nature will help. Is that the beauty of slow gardening?

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    1. Hi Denise, I suppose it is a slow gardening thing, to try to work with nature. But of course being passive doesn't always work, and when you're feeling desperate there's always the direct action method, known as the 'squish'.

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  5. I agree with Denise, you did the right thing, let nature take care of itself. You have many fine critters in the garden, and nice photos to show for it. Your hoverfly photos are my favorite.

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    1. thanks Donna, I was pleased with the spider photo, it took ages and lots of tries to capture the details of the spider because it was very small.

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  6. In our garden, I see ladybirds chowing down.

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    1. I love ladybirds, haven't seen any in my garden for years and years. Don't know why.

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  7. Great post! I sometimes worry about aphid damage, but then ... along comes another critter to eat them! This summer I had Milkweed aphids on my Milkweed, and read some forums about how devastating they can be. So I blasted them off with water. A couple of days later, I saw lady beetles feeding on what was left of the aphids! Yay! You certainly have lots of beneficial insects in your garden!

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    1. I agree - yay! Water blasting is temporary fix, lady beetles get rid of them for good - till the next lot come along. The thing is, I'm almost pleased to see them now, because otherwise what will the other insects have to eat?

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  8. Just one more reason to never use pesticides. Nature will take care of itself. But if I have more aphids than the local predators are hungry for, I just squish them.

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    1. Direct action can be very satisfying.

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  9. Very interesting post Catmint! Insects make themselves at home in garden so naturally. It is so important to know them better. Now I know a larva can feed on aphid. TQ for this informative post. The photos are amazing. Good shots!!

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  10. Fascinating information and photos! And - methinks a mystery writer is budding in your garden!!

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  11. Okay, you have to turn this into a children's picture book! The text would hardly need changing at all. On a more garden-y note, I noticed lots of aphids on my new Hellebore shoots a month ago - never seen them there before. But as usual with aphids, I just let any predators around get to work, and now I can't find one aphid on the Hellebores or the roses. My mother sprays whenever she sees aphids, and she has them all summer long. I never see any once the weather has warmed up. Sadly, I can't convince her to stop.

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    1. Hi Lyn, I actually did write a children's story, and put it in the blog - here's the link: http://slowgardener.blogspot.com.au/2011/12/lost-in-garden.html
      Re your mother spraying, I've noticed lots of people see a spider or insect and without thinking squash it. I get quite upset whenever I see it.

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    2. That was a cute story - I especially liked the bears in their very small house! But I still think the aphid one has potential.

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    3. Thanks for the encouragement. I'll keep you posted if anything comes of it.

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  12. Over here, we too have lacewings and their larva eat the aphids, also ladybirds and their larva eat them. Plus the bluetits enjoy a good munch on them, they really don't last long here.

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    1. I did wonder if any birds ate them, but lately the big birds seem to have scared the little birds away. We're all lucky if we have a good range of biodiversity in our gardens.

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  13. Hooray for those aphid-hungry larvae! I watched a little bird picking aphids off my rose bush this fall, cheering it on the whole way. And I found various stages of ladybug larvae on my roses as well, chomping away on the aphids. Good help in the garden is so hard to find, especially unpaid. Gotta love those little bugs.

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    1. Hi VW, beautifully put - i.e. good help in the garden so hard to find ... lol!

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  14. Very interesting post! My husband hates wasps and often carries a can of insecticide with him, a practice that hurts my organic soul. Then I read that wasps eat aphids! So I persuaded him to be more moderate with his spraying, since he hates aphids as much as he hates wasps.

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    1. Good persuading! That's what people found out to their cost - eliminate one species and you end up with too many of their food source. European wasps are nasty pests here, very scary and aggressive, but I wouldn't spray them, because chances are other insects would be harmed.

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  15. A nice bit of sleuthing dear Catmint! Isn't nature fascinating (and a little scary?)

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    1. ... and incredibly complicated, ambiguous at times and with so much to learn!

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  16. Oh I love nature and how she takes care of things like this

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    1. It's great when it works out like this it did this time.

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  17. Hooray, hooray, hooray! Three cheers for the beneficials! I usually don't mind seeing a few baddies in my garden, knowing they will attract the good guys to my garden. Great closeups and information!

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    1. thanks, Holley. I used to get upset seeing baddies, now it's all part of trying to understand the ecosystem.

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  18. You are so patient to wait for the aphid eaters. Lovely shots too Sue have a nice weekend.

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  19. Hi Sue
    I keep hearing how the ladybirds take care of the aphids, never see enough of them at the right time though. We do get plenty of hoverflies, not as big as your magnificent specimen.

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    1. Dear Alastair, I laughed when I read this. There are no monster Australian hoverfly species that I know of! Our hoverflies are tiny too. I just got close up with the camera.

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I love to get feedback and comments, and getting to know other bloggers. I also appreciate corrections if you detect an error, because I'm not an expert, but a self taught enthusiastic amateur on a steep learning curve.

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