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Lady beetles working hard in our gardens, thank goodness

Aphids the meal of choice for the beloved beneficial insect


Lady beetles on chard
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)

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 .

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.

My community garden plot contains flowering plants, though the most popular plant this spring has been the chard plant, which attracted hordes of aphids -- and subsequently became Club Chard for a bunch of sevenspotted lady beetle adults and larvae (the  teenagers of the lady beetle family).

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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Garden Checklist for week of July 7

Take care of garden chores early in the morning, concentrating on watering. We’re still in survival mode until this heat wave breaks.

* Keep your vegetable garden watered, mulched and weeded. Water before 8 a.m. to conserve moisture.

* Prevent sunburn; provide temporary shade for tomatoes, peppers, eggplant, melons, squash and other crops with “sensitive” skin.

* Hold off on feeding plants until temperatures cool back down to “normal” range. That means daytime highs in the low to mid 90s.

* Don’t let tomatoes wilt or dry out completely. Give tomatoes a deep watering two to three times a week. Harvest vegetables promptly to encourage plants to produce more.

* Squash especially tends to grow rapidly in hot weather. Keep an eye on zucchini.

* Some weeds thrive in hot weather. Whack them before they go to seed.

* Pinch back chrysanthemums for bushy plants and more flowers in September.

* Harvest tomatoes, squash, peppers and eggplant. Prompt picking will help keep plants producing.

* Remove spent flowers from roses, daylilies and other bloomers as they finish flowering.

* Pinch off blooms from basil so the plant will grow more leaves.

* Cut back lavender after flowering to promote a second bloom.

* One good thing about hot days: Most lawns stop growing when temperatures top 95 degrees. Keep mower blades set on high.

* Once the weather cools down a little, it’s not too late to add a splash of color. Plant petunias, snapdragons, zinnias and marigolds.

* After the heat wave, plant corn, pumpkins, radishes, winter squash and sunflowers. Make sure the seeds stay hydrated.

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