Based on my personal experience in the last few months, I have to say, “yes and no.” (Nothing like a definitive answer, is there?)
Certainly they seemed to have absolutely no effect whatsoever on whiteflies, aphids or Argentine Ants. However, I observed sow bugs and earwigs leaving the plots treated with worm castings.
This performance did not match the claims of George Hahn, president of California Vermiculture and distributor of Wormgold Worm Castings. You may recall Mr. Hahn contacted me not long after my “Go Away! Ant That Means YOU” made it into print, to say his product had been proven successful in repelling whiteflies, aphids and ants from Southern California gardens.
The experts I consulted disagreed, so I decided to see for myself. I applied Wormgold worm castings in one of two similar flowerbeds in my front yard, carefully following Wormgold’s instructions. I also treated Sophie’s hibiscus plants across the street.
Sow bugs and earwigs immediately left the treated area and did not return for several months that I could see, even though I found them in other, worm casting-free areas.
Unfortunately, this good result was offset by the fact that the Argentine ants, whiteflies and aphids only seemed to be temporarily repelled by the frequent watering called for in the worm castings application instructions. When the beds dried, these insects returned in force.
Possible explanations for this unsuccessful result: 1) worm castings can NOT accomplish the tender miracle of ant/whitefly repellency; 2) worm castings CAN accomplish tender miracles but Sophie’s hibiscuses are atheists and therefore resistant; or 3) the worm castings I purchased were stale. (I’m just guessing here… you want a more scientific answer, go talk to a scientist.)
So how to explain Wormgold’s preliminary testing results showing Wormgold Castings repelling Red Imported Fire Ants (RIFA)?
Frankly, I believe the application of the castings disturbed the mounds, stimulating the ants’ natural protective instinct to pack up and move away.
If there was one thing I learned in Texas while battling RIFA with pesticides and bait, it was NOT TO DISTURB THE MOUNDS, because the ants will move the nest a few feet away, presumably where there is a better school district and less noise.
Still… let me tell you about a super-gardener I met once. She fertilizes her garden with nothing but worm castings produced by what she calls her “herd” of red wigglers, which she keeps in plastic bins on her property. Her garden is filled with healthy, vibrant plants, which appear to be free of insect pests.
This observation (and my belief in Mr. Hahn’s sincerity) makes me think that perhaps a better way to perform a this experiment would have been with fresh worm castings instead of store-bought, which everybody knows is never as good as when it’s made from scratch.
Better yet, learn how to raise your own herd of red wigglers from these sites:
- Recycle with Earthworms: the Red Wiggler Connection, by Carlsbad’s very own worm experts, Shelley C. Grossman and Toby Weitzel. If you can’t get a copy of their book directly from them, try Amazon or your library.
- If that fails, try the vermiculture classic, Worms Eat My Garbage: How to Set Up and Maintain a Worm Composting system by Mary Applehoff.
- Worm Digest Lots of info here, including back issues, links, a library, and a “worm tour.”
- Composting with Red Wiggler Worms, published by City Farmer, Canada’s Office of Urban Agriculture
- Worm Composting, by the Sonoma County Waste Management Agency.
Did You Know?
Argentine ants have successfully supplanted Southern California’s native Harvester ants and carpenter ants because 1) they have no natural predators and 2) they are so genetically similar in Southern California that they regard each other as members of the same colonies.
Elsewhere in the world, Argentine ant colonies go to war over territory, but here they form “super colonies.” (See San Diego Union-Tribune article dated 16-May-2000, “ARGENTINE ANTS DECIDE TO MAKE CALIFORNIA HOMES THEIR OWN: Insects form massive family, UCSD finds.” )