Saturday, June 30, 2018

Creeping Jenny Eaten By Sawfly Larvae

What's eating my Creeping Jenny?


Golden Creeping Jenny (Lysimachia nummularia 'Aurea'), is a staple in any garden. Used as a perennial ground cover or trailer for containers and hanging baskets - it grows in sun or shade.

So when I walked through the garden this morning, something was awry. I noticed foliage had been eaten; nearly every leaf was damaged.

On closer inspection, these Monostegia abdominalis larvae were happily munching away. Grrrr.


Great, here's another alien insect, reeking havoc in Ontario. Another introduction from Europe we don't need.

These "caterpillars" are in fact sawfly larvae.  Check out this link by Kansas State University to see the difference.


In total, I collected 23 from this one spot.

They are known to feed on foliage within the Loosestrife family of plants, which Creeping Jenny Lysimachia is classified under.

No spraying necessary, it took me no more than 4 minutes to gather them. They are quite easy to find as their silver/grey coating is a great contrast to the lime green foliage. Do Note: once you touch them, they coil and drop off the leaves.  They are known to have 2-3 life cycles per season. These came out in late June, so keep checking your plants for any other generation that may come 'calling'!

One bonus, they became a great snack for our Koi fish in the pond.

Here's Wikipedia's taxonomy description:  Monostegia abdominalis


16 comments:

  1. Hi Heidi...I just came back from holidays and was shocked to see the side of my yard where I planted ground covers. The Bugleweed and Lamian were not affected at all, but the Creeping Jenny was decimated with only the stems remaining. I saw the exact same larvae as you have pictured above. There are hundreds of the larvae....you said to just pick them off...but that would be an impossible task with the amount I have. Do you have any other suggestions for getting rid of them? Thanks in advance !

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    1. I know - they are quite the heavy eaters. You probably had two or 3 adults lay eggs in one area. There are no chemical controls that you can use here in Ontario - unless you have a pesticide license to spray. I'm afraid picking them is your best bet or using safers soap and truly spray them off the foliage. Invite birds to your garden, with water baths and bird feeders. Robins would have a frenzy of fun eating them, if they knew they were there! Good luck!

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    2. I just picked 117 off my creeping jenny. I’m sure there will be more.

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  2. I too had a shock last night, and in desperation sprayed them with dishwasher soap. Many were dead already this morning and those not, were speayed again, turned green, loose and hopefully dead. Must check again later.

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  3. I have this problem too. I have a large area with this ground cover. I could never pick them off....there are several hundred! If I do nothing, are the sawflys harmful? I've never had this happen before... I've been gardening for many years. Any info is helpful... thanks...Livonia, MI (metro Detroit)

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  4. Spotted sawfly larvae on my moneywort yesterday morning and began picking them off the plant. Total of 576 removed in two days. Time-consuming effort. Can I safely use watered down solution of Dawn dish soap without hurting the plant?

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    1. You can try - but since Dawn is a soap, and there are beneficial insects and micro-organisms in the soil beneath, be wise on how much comes in contact with the soil.

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    2. They've totally decimated my creeping Jenny this year, despite spraying with vinegar water, and then with insecticide. It's been an ongoing battle for years, and this year they just got totally out of my control. I'm going to dig up and replace the plant, as I'm losing this battle.

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    3. I sprayed them with ammonia water which I use for slugs. It seemed to do the trick.

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    4. What ratio do you use to kill them? Half and half?

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  5. I was picking them off and saw that they drop off like Japanese beetles do to escape. There were more on the ground than what I had collected. I’ll have to return tomorrow.

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  6. I've had them for thirty years on the creeping Jenny in my front border. When they show up, and it gets ragged looking, I pull most of it. Not roots and all, just a good haircut. The plants recover nicely. I've never treated them. I never see any birds eating them, maybe because they are alien.

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  7. Try shaking Diatomaceous Earth on the leaves.

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  8. Neem oil works kills larvae and stops eggs from developing

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  9. I also heard that vinegar and water mix are a great way to get rid of a lot of plant destroying insects. Just tried this on my creeping Jenny and it seems to be coming back. Hoping this works.

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  10. They are decimating my columbine and hostas! I tried the vinegar and water. Hope it works!

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