Tag Archives: ants

organic, kinda sorta

I suppose saying that your gardening methods are mostly organic is like saying you’re slightly pregnant. If you’re a total purist this is a yes/no sort of thing. I try to keep away from most chemicals, but every now and then something pushes me off the wagon.

Mealybugs ugh ugh ughA few days ago I discovered that there was a sudden and massive infestation of mealybugs on one of my plantings of green-eyed gloriosa daisies, Rudbeckia hirta. In addition to the mealybugs, there was a major trail of ants going into the bed.

I’ve posted before about the symbiotic relationship some fungi and critters have with ants. Since then I’ve read how another critter–bumblebees–have been increasing their dependence on the honeydew produced by sucking insects, in this case, aphids. Apparently the bumblee population has crashed in Scotland, likely because of habitat loss that has destroyed many of the plants they depend on. To compensate, the bumblebees have been visiting plants infested by aphids and feeding off the sweet goo the smaller critters produce. The aphid goo, however, lacks the essential proteins that plant nectar provides the bees, and the bees are suffering even more.

In dealing with my ant-mealybug problem I didn’t want to use a bunch of poisons, partly out of principle, partly out of the fact that the affected plants sit right outside the kitchen window–not a place I wanted a pile of toxics.

My solution to this problem was two-pronged: try to control the ants that were cultivating the mealybugs, and reduce the number of mealybugs on the plants to give them a fighting chance.

I’ll start with the mealybug control steps because that was the organic part. You can knock down mealybug populations to a certain extent using a strong blast of water. You can also use a non-toxic substance like insecticidal soap. With people heading over to the house this holiday weekend, I opted for the latter approach, hoping the control would be quicker and more thorough. A thorough squirt to cover stems and leaves–top and bottom–has reduced their number considerably. I’ll repeat in a couple of days to try to drop the population further.

The ant control part was more difficult. Some species can be controlled by a mixture of borax and sugar left near their trails, but unfortunately my ants didn’t care for my cooking. Dishwashing detergent mixed up with water can sometimes be poured onto their nests to control many of the ants that come in contact with it, but effects don’t last long. Ants dislike cucumbers, so you can sometimes keep them away by spreading cucumber peelings. But once again, that can have limited effects.

So out came the barrier spray that I used once this year to keep them out of the house after everything else failed. The hardscape around the plants got a quick perimeter line of the stuff, as did a couple spots where the ant line crossed some bricks. A quick touchup a couple days later and so far they seem under control.

So, yes, I did let a few squirts of chemicals into the garden, but compared to spraying the plants all over with something poisonous, this seemed like a reasonable compromise.

So is this organic? Not really. But it’s a good way to reduce dependence on chemicals by taking a more systematic approach to pest control.

ant farm[ers]

So…you think humans are the only critters who farm and garden? Think again. From a Science in Brief column in yesterday’s LA Times comes this about ants:

Study finds ants longtime farmers

Ants took up farming some 50 million years ago, according to researchers who traced the ancestry of farmer ants.

An analysis of the DNA of farmer ants traced them back to an original ancestor — a sort of Adam ant, at least for the types that raise their own food, according to a paper published in the online edition of Proceedings of the National Academy of Sciences.

In the last 25 million years, ants have developed different types of farming, including the well-known leaf-cutter ants. Leaf-cutter ants don’t eat the leaves they collect. Instead, they grow fungus on the leaves and eat the fungus.

Only four types of animals are known to farm for food — ants, termites, bark beetles and, of course, humans. All four cultivate fungi.

If you have online access to that journal, you can read the full article at: http://www.pnas.org/cgi/reprint/0711024105v1. There’s no research on whether ants prefer to create formal gardens or naturalistic ones, though I’d guess aesthetics aren’t hight on their list of concerns.

To that, I’d also add that some ants are also livestock farmers in that they cultivate other animals. Aphids and ants have a symbiotic relationship, with ants tending aphids to share in the sweet nectar they exude. And all last year we had a major ant trail leading from the ground into the grapefruit tree, where ants and scale insects had set up shop on the skins of the young grapefruits. It didn’t seem to affect the grapefruits too much, though we always had to remember to scrub them clean before serving them up. Here’s a link to a related story on ants and scale insects in tropical coffee plantations.