Aphids the meal of choice for the beloved beneficial insect
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They dropped into Club Chard for a feast: Three of about a dozen sevenspotted lady beetles (
Coccinella septempunctata
)
were dining on aphids in my community garden plot. (Photos: Kathy Morrison)
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If there were a "Trending Topics" list among gardeners right now, "Lady Beetles" (aka ladybugs) would be at the top.
The colorful and beloved insect is back in our gardens in a big way this spring, working hard for us by doing what comes naturally: Eating aphids.
Almost every conversation I've had lately with a fellow gardener has included a comment about "so many ladybugs!" It happened again Wednesday during the Open Garden at the Fair Oaks Horticulture Center, as the bright little beetles were easily seen among the fronds of the white yarrow ( Achillea millefolium ) that I was trimming. Visitors to the Herb Garden area spotted lady beetles on the Scarlet Unique geranium ( Pelargonium fulgidum ) and other plants nearby. Master gardeners had also seen quite a few in the orchard trees the previous week.
So, hurray for Mother Nature's beneficial predators!
But why so many this year? Are there more aphids attracting more lady beetles? Or are the conditions just right for the beneficials this year? Or are we simply more aware of the importance of biological controls?
It might be a combination of those factors, but cold does kill aphids, and we didn't have much cold this past winter. (Temperatures above 90 degrees also kill them, which is why aphids are less of a problem here during summer.) Moderate temperatures of 65 to 80 degrees are their ideal climate. More aphids available means more food for more lady beetles, who overwinter in protected areas.
What if your garden is full of aphids but hasn't yet become a home for lady beetles? Ideally, the garden should include plants that entice beneficials with nectar and habitat, then encourage them to stick around. Yarrow is a good one for spring, along with alyssum, lobelia, thyme, cornflower, calendula, geraniums and marigolds. Here's an excellent list of plants for all beneficials .
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See that alligator-looking insect in the lower middle of the photo? That's
a lady beetle larva, aka voracious teenager. They eat even more
aphids than the adults do.
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An easy way to fight aphids is to blast them off the plant with a strong spray of water. (Tip: Hold your free hand behind tender rosebuds to avoid blasting the buds off as well.) However, some gardeners try to buy containers of lady beetles and deposit them in the garden -- and then are mad when the insects fly off. Is this a commercial scam?
Well, no, but there are better and worse ways to handle the release of lady beetles. A blog post by UCANR's Mary Louise Flint tackles this question: "University of California research has demonstrated that lady beetle releases can effectively control aphids in a limited landscape or garden area if properly handled and applied in sufficient numbers." Note the "limited" and the "if," and take a look at the full blog post to learn how it can be done.
Here's another thing about those commercial lady beetles: They're not residents of the Central Valley flatlands. As Flint notes, "Lady beetles sold at nurseries for aphid control are convergent lady beetles, named for the converging white marks on its thorax. Suppliers collect beetles from large overwintering aggregations in California's foothills and mountains. Many other species of lady beetles occur naturally in California landscapes but don't aggregate in the mountains and aren't sold commercially."
And, psst, don't buy lady beetles that haven't been refrigerated at the store. Those room-temperature insects are active and climbing all over each other, resulting in a lot of casualties.
Even under the best circumstances, expect purchased lady beetles to fly away after a few days. Their mission accomplished, they're off to find more caches of yummy aphids. Or maybe just heading home.
(For more on lady beetles, check out this detailed and illustrated page from the UC Integrated Pest Management.)
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Dig In: Garden Checklist
For week of Dec. 3:
Make the most of gaps between raindrops. This is a busy month!
* Windy conditions brought down a lot of leaves. Make sure to rake them away from storm drains.
* Use those leaves as mulch around frost-tender shrubs and new transplants.
* Rake and remove dead leaves and stems from dormant perennials.
* Just because it rained doesn't mean every plant got watered. Give a drink to plants that the rain didn't reach, such as under eves or under evergreen trees. Also, well-watered plants hold up better to frost than thirsty plants.
* Prune non-flowering trees and shrubs while they're dormant.
* Clean and sharpen garden tools before storing for the winter.
* Brighten the holidays with winter bloomers such as poinsettias, amaryllis, calendulas, Iceland poppies, pansies and primroses.
* Keep poinsettias in a sunny, warm location. Water thoroughly. After the holidays, feed your plants monthly so they'll bloom again next December.
* Plant one last round of spring bulbs including daffodils, crocuses, hyacinths, anemones and scillas. Get those tulips out of the refrigerator and into the ground.
* This is also a good time to seed wildflowers such as California poppies.
* Plant such spring bloomers as sweet pea, sweet alyssum and bachelor buttons.
* Late fall is the best time to plant most trees and shrubs. This gives them plenty of time for root development before spring growth. They also benefit from fall and winter rains.
* Lettuce, cabbage and broccoli also can be planted now.
* Plant garlic and onions.
* Bare-root season begins. Plant bare-root berries, kiwifruit, grapes, artichokes, horseradish and rhubarb. Beware of soggy soil. It can rot bare-root plants.
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