Do Worms Control Aphids In The Backyard Garden?

worms vs aphids graphic

Here’s an interesting little factoid for you brought to you by the Centre of Plant Science, Berlin, Germany. Lead researcher Susanne Wurst reported in Entomologia Experimentalis et Applicata, October 2010, that there is some relationship between aphids on a plant and earthworms in the soil.

In greenhouse trials, aphids tended to congregate on tansy plants in haphazard ways in a trial. When the researchers investigated futher, they found that the plants with no or reduced aphid problems all had earthworms in the soil.

It would seem the earthworms was able to add “something” to the soil, absorbed by the plant and transferred to the leaves to make the plant less palatable to aphids.

While this is only one report and you can’t draw conclusions in any rigorous way, it is tempting to wonder how we can use this in our gardens.

For example, what if we put worm compost around plants such as impatiens and roses that were aphid magnets. Will this do anything?

I have absolutely no idea but it’s intriguing to ask the question and it can’t really hurt to toss some worm compost around the garden just in case. At worst, you’re wasting a bit of time (I’ve done worse time-wasters in the garden) and at best, you’re adding an unknown level of plant protection.

And yes, the next question is where do you get worm compost? 🙂

Check your local garden center or if all else fails, here’s a link to

Should You Use Worm Bin Leachate In Your Garden?

If you have a worm compost bin you might want to consider using the leachate at as a foliar spray.

FYI: The “leachate” is the liquid that sometimes accumulates on the bottom of the bin if you don’t have enough absorbent material in the bin.

Researchers in India report that worm leachate applied as a foliar spray at a low concentration (two milliliters per liter of water) to strawberry plants at 30-day intervals during the growing season resulted in better plants than control plants sprayed with clear water.

*Increased leaf area (by 10-19%),
*Increased dry matter per plant (by 14-27%),
*Higher fruit yield (by 10-14%),
*Reduced numbers of malformed fruits (by as much as 11%),
*Less incidence of gray mold (by as much as 5%), and improved firmness of fruits.

This worm bin leachate wasn’t aerated and it was stored in a refrigerator for up to 75 days. In a previous study, the effects on tomatoes was similarly improved (attributed to the humic acid in the leachate).

This falls into the “dont’ know if it’s true but it likely can’t hurt” category. 🙂

And for the record, I wouldn’t do this as it’s just one of those things that “may” give you some increased yields but is more work than the results may warrant on the home garden. But at least now you know what one study has shown.

Rajbir Singh (Directorate of Waste Management, Bhubaneswar 751023, Orissa, INDIA), et al., “Sequential Foliar Application of Vermicompost Leachates Improves Marketable Fruit Yield and Quality of Strawberry (Fragaria × ananassa Duch.),” Scientia Horticulturae 124(1), February 26, 2010, 34- 39. (Elsevier Science B.V., Molenwert 1, Postbus 211, 1000 AE Amsterdam, THE NETHERLANDS.)

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