Of Pests and Patience

WARMER WEATHER BRINGS BUGS, and that often causes gardeners a lot of worry. When a prized plant starts to look chewed, or if it is suddenly found to be hosting a few million aphids, a gardener is bound to wonder, Should I be doing something?

So here's the good news: Probably not.

Umbra Fisk, who is the advice columnist for the online environmental magazine Grist, recently fielded a question from a reader who wanted to know whether she should buy dormant lady beetles to combat whatever is eating her basil. (If this gardener is growing basil now, obviously she does not live anywhere near me.) Umbra replied with an excellent explanation of how to use natural pest control techniques to combat oest insects, but I think she missed one of the most important tools in any natural gardener's arsenal: namely, patience.

This is what I said in the comment I left at the Grist website (a couple of additional comments follow):

One of the principles of natural pest control is that you have to have pests in order to have natural pest predators. So, paradoxical as it may seem, patience is often one of the most important weapons a gardener can use against pests.

Insect outbreaks follow a typical pattern: The population of pest insects skyrockets, which eventually attracts predators. Once the predators are assured of a reliable food supply, they breed, which produces a lot more predators. The pest outbreak then begins to subside as pest insects are gobbled up. But this process takes time. If it's disrupted (for instance, by an impatient gardener who decides to resort to pesticides), it may never happen at all.

Sometimes predators can't keep up with an insect outbreak, of course, which is why Umbra is quite right to say that it's best to know what you're dealing with. However, it's amazing how often patience pays off. Your friendly local predators will come to the rescue--but you have to give them a chance!

Incidentally, Umbra is also quite right to warn people off importing insects to the garden. If you provide good habitat and avoid using pesticides, most likely there are plenty of local predators, from lady beetles to wrens and other birds, that will be more than happy to control pest insects for you.

I didn't say this in my comment at Grist, but this is particularly true of aphid outbreaks. Lady beetles and birds seem to love aphids so much that I have taken to referring to aphids as "bird ice cream." In all my years of gardening, only once have predators failed to control an outbreak of aphids. (That was an outbreak of black aphids on fava beans, and I think the fava beans were stressed because I wasn't watering them often enough.)

Another additional comment is that pest insects are particularly unlikely to be a problem if you're gardening with native plants. Unlike some vegetables (which do seem to be prone to insect attacks that even the most gluttinous birds and insects can't defeat), native plants are adapted to coexistence with both native insects and their predators, and often can spring back even from quite severe insect assaults. The exceptions usually occur when they have to cope with a non-native insect that has no natural predators or when human activities have so altered the local ecosystem that the natural balance has been lost.