While searching for pictures for this post, I stumbled upon a depressingly large number of websites dedicated to the extermination of insects. Commercial sites, plant pathology sites, university sites, cooperative extension sites, gardening sites, sites devoted to jihad against one particular bug, all invoking death to the six-legged and the arachnids they rode in on. No wonder world peace has at best an ice cube’s chance in hell: we can’t even manage coexistence with creatures we can barely see without running for things to kill them with.
Well, that’s why they invented Zoloft and British cozy mysteries and aptly monikered Wendy Cope.
I would like to make clear that, despite the title of this post, no bug is bad in any moral sense. They merely do what they were born to do. Those Japanese beetles skeletonizing the foliage on your favorite rose bush bear you no personal ill-will. They’re just being Japanese beetles trying to stay alive long enough to reproduce. It’s called “the biological imperative,” and all living things are subject to the mandate to some degree. It’s not synonymous with “evil” in any species.
That being said (and my conscience assuaged), gardeners often find some common insects, er, problematic. (I refer here primarily to ornamental gardeners: those who grow edibles are beset by woes we flower-lovers can’t even begin to imagine.) Said insects generally fall into two categories: sucking pests and chewing pests.
In my neighborhood, the plant-juice suckers outnumber the plant-leaf-and-fruit chewers by a wide margin. Why? Just lucky, I guess. And of all the suckers, the one we see most of is scale.
Now, I said “scale,” singular. That’s misleading. There are lots and lots of scales. You got your soft scales and your armored scales; your black, brown, red, white, rose, olive and calico scales; your euonymous, holly, magnolia, camellia, oleander, palm, hemlock, pine, oak, elm, beech, juniper, fern, peach, and walnut scales; your California, Florida, Indian, Chinese, European and San Jose scales; scales named for people named Fletcher, Maskell, Forbes, Townsend, Putnam and Boisduval. Scales can be gloomy, obscure, frosted, irregular, elongate or scurfy; they might resemble wax, barnacles, terrapins, tortoises, oyster shells, umbrellas or cottony cushions. All together, North America is home to about 1240 species. And they all suck.
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| Tea scale on the underside Chinese holly leaves |
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| A cottony cushion scale convention that killed this cleyera twig |
Pictured above and below are four we see a lot of. Tea scales fall under the rubric of armored, although they’re too tiny for us to make out individuals. They love camellias (which is why they’re called “tea”—don’t tell me you didn’t know the tea we drink comes from Camellia sinensis), Chinese hollies and Chinese ligustrums. As its name suggests, cottony cushion is a soft scale. Pyracantha is a favorite of theirs, as is cleyera. Also softies in a gooey sort of way, wax scales are largely tropical, but a few species do quite well in the southern U.S. We find them on hollies, pears, camellias and magnolias. The brown scale here looks like it ought to belong in the armored class, but it’s soft too. We encounter this kind less often than the others, but usually in large infestations. The worst case ever seen by Fitzgeralds Gardening occurred on a trio of ‘Little Gem’ magnolias that were planted too deep; ergo, badly stressed. The second worst instance was on willow oak.
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| Aptly named wax scale |
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| Also aptly named brown scale |
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| The upper sides of lacebugged azalea foliage |
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| Newly hatched lacebugs on the underside of an azalea leaf |
Do your azalea leaves look like the ones pictured here? If so, you've got lacebugs. Don't confuse these miniscule suckers with the lovely, beneficial, diaphanous-winged lacewing: like Texas, lacebugs are a whole other country. In the neutral to alkaline soils of coastal North Carolina, lacebugs are as certain as death and taxes on acid-loving, stressed-out azaleas.
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| Whiteflies and their eggs |
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| A herd of yellow aphids |
When it comes to sucking the life out of gardenias, whiteflies rule. For crapes and many perennials, it’s aphids. Spider mites—not true insects but arachnids—plague conifers and houseplants. All these creatures have marvelous mouthpieces exquisitely adapted to extracting plant juices from leaves. I’d appreciate them more if they didn’t cause foliage discoloration, distortion and death.
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| Itty-bitty red spider mites |
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| How to tell if you have spider mites: stippled leaves and webs (click on this one to see the details) |
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| This is what sooty mold, caused by "honeydew," looks like |
A corollary problem of all sucking insects is their poop. Named “honeydew” by some horticultural wag, the excrement falls on and proceeds to stick to surrounding foliage, covering it with an unattractive matte black coating of moldy recycled plant juices. Fortunately, it’s largely a cosmetic problem, fairly easy to remove. Just follow the instructions in the “Quick Tips” post of April 5.
Treat scales, whiteflies and mites with all-season horticultural oil (UltraFine is one brand). Their soft coverings make soft scales susceptible to the smothering effects of oil at all their life stages. Armored scales are tougher to kill because of their, well, armor. Horticultural oil works on the more casually outfitted crawler stage, and can be somewhat effective on the immobile ones. In winter, heavier dormant oil formulations might make a dent in populations. Hand-picking, scraping or pruning out heavily infested branches might be your best bet if scale is your problem. Trickier to control because of their life-long mobility, whiteflies and mites require patience and vigilance to overcome. Hort oil and insecticidal soaps work IF the insect or its eggs get coated by the application. Repeated dosings according to package directions will probably be necessary.
Aphids, on the other hand, are easy to get rid of. You can blast them with a strong jet of water from the hose or squish them by hand. The squeamish among you can drench them with insecticidal soap. Nothing stronger is ever required for these suckers.
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| A moderate infestation of the dreaded azalea caterpillar can defoliate an azalea (duh) in a week or two |
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| Two-striped grasshopper |
The other main class of insect pests is the chewers. This group is better known, mainly because they’re bigger; hence, more visible. Grasshoppers, Japanese beetles and the larva of less beautiful butterflies and moths are the most common examples. The good news is, if you pay attention to what’s going on in your garden, you can keep the damage to acceptable levels by mechanical methods… which means hand-picking, hand-shooing, flicking slow-moving offenders into jars of soapy water, and, in the case of the ones who build little houses, destroying same. Spraying insecticides does no good if you don’t make contact with the target. Such chemicals never act preventively, so don’t bother.
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| Tent caterpillars in their cozy home |
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| This is the bag the bagworm lives in |
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| Your basic grey garden slug |
One last chewer—sort of—outside of the realm of true insects is the slug and its agoraphobic cousin, the snail. These slimy guys are gastropods, literally “stomach foot.” That’s how these nocturnal creatures tatter your hosta leaves: they extrude their stomachs through their foot, which is pretty much the whole body except the head. Another instance of elegant design in the invertebrate kingdom, slugs are easy to deter. Coffee grounds, coarsely broken eggshells, diatomaceous earth or rings of copper tubing around susceptible plants distress delicate foot-tummy tissues that attempt to cross them. Saucers of beer draw these little sots like magnets to drowning, but very happy, deaths. Eliminate daytime hidey-holes by cleaning up piles of damp debris and discarded boards. Encourage toads, major slug predators.
The best way to discourage pests? Grow unstressed plants whose natural defense mechanisms are in full vigor. Let the trinity of right plant, right place, healthy soil be the launching pad for your pest-controlled garden.
Still more bugs next time. Thanks for dropping by.
Kathy
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