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This predator is fascinating, colorful — and problematic

Praying mantid can be both good and bad

Purple mantid on lavender rose
A mantid has changed color while hanging out on a Fragrant Lavender Simplicity rose. (Photo: Debbie Arrington)

This fascinating creature changes its color to blend into its surroundings. When that backdrop is a purple or orange rose, that makes for interesting camouflage.

This August, I’ve been watching the praying mantids that inhabit my rose garden. They have an appetite for aphids, which makes them welcome on my no-spray bushes.

But really, mantids will eat anything that comes near their huge forelegs, which also makes them problematic. They’re a beneficial insect that also eats other beneficials, such as bees or butterflies.

Recently, I watched in horror as a mantid ripped off the head of a little sweat bee that had come too close to the floribunda where the predator was lurking. The mantid watched me as it ate, cocking its triangular head as if waiting for a reaction. “That’s not very nice,” I scolded, too late to help the poor bee.

What would you expect? Mantids aren’t nice; the females famously cannibalize their own species after mating.

Their indiscriminate consumption of other insects has downgraded the praying mantid (or mantis) status as garden good guy. The UC Integrated Pest Management pest notes do not recommend their introduction.

“Although mantids are fascinating creatures, they are of no benefit for biological pest control,” say the pest notes. “Mantids feed on any insect they can catch, and commonly prey indiscriminately on beneficial and nonpest species including bees, butterflies and syrphids. Even if mantids specialized on pests, this likely would be of little benefit; mantids are relatively inactive, and despite their large size, each individual consumes relatively few insects.”

Adds the UC Cooperative Extension master gardeners, “As mantids consume both pests and beneficials, they are difficult to use reliably for biological control.”

Nonetheless, I let my mantids continue to roam my rose beds, if only for the entertainment. No other insect puts on such a colorful show – and it doesn’t eat the roses.

One morning, a mantid might be bright green and roam onto a rose in search of food. By afternoon, it’s the same shade as the flower – pink, orange or purple. And it doesn’t mind if people watch.

For more about mantids here:


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Dig In: Garden checklist for week of Jan. 29

Bundle up and get work done!

* Prune, prune, prune. Now is the time to cut back most deciduous trees and shrubs. The exceptions are spring-flowering shrubs such as lilacs.

* Now is the time to prune fruit trees, except apricot and cherry trees. Clean up leaves and debris around the trees to prevent the spread of disease.

* Prune roses, even if they’re still trying to bloom or sprouting new growth. Strip off any remaining leaves, so the bush will be able to put out new growth in early spring.

* Prune Christmas camellias (Camellia sasanqua), the early-flowering varieties, after their bloom. They don’t need much, but selective pruning can promote bushiness, upright growth and more bloom next winter. Feed with an acid-type fertilizer. But don’t feed your Japonica camellias until after they finish blooming next month. Feeding while camellias are in bloom may cause them to drop unopened buds.

* Clean up leaves and debris around your newly pruned roses and shrubs. Put down fresh mulch or bark to keep roots cozy.

* Apply horticultural oil to fruit trees to control scale, mites and aphids. Oils need 24 hours of dry weather after application to be effective.

* This is also the time to spray a copper-based oil to peach and nectarine trees to fight leaf curl. Avoid spraying on windy days.

* Divide daylilies, Shasta daisies and other perennials.

* Cut back and divide chrysanthemums.

* Plant bare-root roses, trees and shrubs.

* Transplant pansies, violas, calendulas, English daisies, snapdragons and fairy primroses.

* In the vegetable garden, plant fava beans, head lettuce, mustard, onion sets, radicchio and radishes.

* Plant bare-root asparagus and root divisions of rhubarb.

* In the bulb department, plant callas, anemones, ranunculus and gladiolus for bloom from late spring into summer.

* Plant blooming azaleas, camellias and rhododendrons. If you’re shopping for these beautiful landscape plants, you can now find them in full flower at local nurseries.

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