How To Defend Against House Plant Bugs

The very best articles on bugs always start off by suggesting you buy “clean stock from reputable dealers,” which has always seemed a little silly to me. No dealer, reputable or otherwise, likes bug-infested plants any better than you or I; and who among us, for heaven’s sake, is going to purposely buy UNclean plants? Insects can happen to any plant, any time, any place, and the old saying “them as has, gits,” certainly applies here; anybody who has plants will, sooner or later, get bugs on them.

Properly speaking, bugs are not bugs but are, instead, insects. And according to Noah Webster, the term may refer to any of “numerous” small invertebrate animals. And numerous these pesky little things are, too; just when I think I’ve done battle with all the known species, a new one turns up and the fray begins again. (The most recent pest to take up residence on my house plants is oat thrips . . . and I’m not within 100 miles of an oat field!)

Whether you call them insects or bugs, or a name not fit to print, the chances are that some or all of the arthropods which will be described here have either already had a merry time with your plants, or will have in the future. Healthy plants which are given the proper care are more bug-resistant than sickly plants, though, so if your indoor garden is in robust shape, you may not need this advice. Personally, I have had very few infestations in view of the number of plants I grow and the number of sources from which I get plants, but every now and then a perfectly healthy plant comes down with a bad case of thrips or aphids or mealybugs; some insects appear so suddenly and in such large numbers, it almost makes one believe in spontaneous creation!

White Flies

The insect that heads my unpopularity list is white fly. Other insects may be annoying, or damaging, or both, but this is even more so! Brush by an infested plant and whiisshh .. . the little things fly off in all directions. Aim a sprayer at them . . . ditto. They suck plant juices, leave the foliage pale and mottled, and are definitely undesirable, and equally hard to get rid of. Of course if you are a “fast draw” with a spray bottle, and can stand on your head to see the undersides of the leaves (where the white flies rest between flights), then eradication should be no problem for you. During warm weather, my method is to lift the plant ever so gently and carry it outdoors without disturbing the flies. There I knock them galley-west with a forcible spray from the hose and run back inside with the plant before the bugs can regroup their forces. If I do this every week for a month, the plant is usually back to normal.

White flies are partial to flowering-maple, coleus, geranium, begonia, fern, fuchsia, and practically any plant you care to mention. I suggest that you isolate any infested plant and then give it the works, either outdoors with water, or indoors with a spray, but if the bugs keep multiplying faster than you can kill them, throw the plant away.

My plant insecticide of choice is natural organic Neem Oil

Mealybugs

The sneakiest bug, and one of the most common, is mealybug. This cottony-looking critter grows up to one-quarter of an inch long, and once it leaves its hiding place in a leaf-axil or flower-cluster, it is easily visible. Unfortunately, it usually stays in hiding until it (he? she?) has multiplied into a whole horde; then they suddenly emerge and are all over the place. Mealybugs suck plant juices, and are definitely damaging besides being fairly repulsive-looking, so get after them right way. I like to lift them off with a small swab which has been dipped in alcohol. The alcohol seems to penetrate the mealybugs’ waxy coating, and a drop or two poured into crevices the swab can’t get to will make the bugs somewhat sick, if it doesn’t kill them outright. After this treatment, spray the plant with clear water to remove the traces of alcohol.

Scale

Scale, or scales, if you prefer, are also partial to practically everything, just like white flies, but prefer woody-stemmed plants like gardenia, croton, citrus plants, ficus, palm, ivy, and the like. One eminent writer described these as “motionless, and unable to move from place to place”… so how come mine progress like crazy along branches and leaves whenever I turn my back? I’m sure that writer must have meant that adult specimens tend to cling limpet-like in one place; the junior members of the clan practically set speed records one week on my gardenia bush!

Scales may grow to one-quarter of an inch in length, and are usually dark-colored. Those that favor my plants are brown or blackish. Sometimes a stream of water will dislodge these, if they are not firmly established, or you can use malathion or Neem oil on them. I prefer to mash individual specimens right in their tracks, or lift them off with the tip of a knife blade. To clear up a bad infestation may mean you have to go over the entire plant every morning for a month or more, but handpicking the varmints won’t damage the plant and it is the surest method I know.

Mites

Maybe your problem is mites? These come in assorted sizes, names and colors, but the most common on my plants is red spider mite. It shows up only when the air is too hot and dry for certain plants, so I suppose the havoc they wreak is my own fault… spider mites cause the undersurfaces of the foliage to look webby and feel gritty, and in no time they can kill the growing tips or the entire plant. A Neem oil and Malathion is effective against these, and so is daily spraying with plain water.

Cyclamen mites, evidently misnamed since they thoroughly enjoy a host of plants in addition to cyclamen, cause stunted, deformed growth. A badly infested plant should, in my opinion, be disposed of, although there are miticides which purport to kill them without damage to the plants. Or if you like your plants par-boiled, you might try dipping them in hot water (above 100 degrees) for ten or fifteen minutes. This is said to be a fairly sure cure. Sometimes you can propagate the plant from a healthy cutting, and discard the most badly infested part; then use miticide to inhibit the growth of any mites which might be lurking on the cutting.

Thrips

Thrips, small, rapid, and black or brown, may be suspected of causing the trouble if your plants have deformed buds or flowers, or if the foliage develops a silvery color. Sometimes forcible spraying with clear water will dislodge them, and neem oil or malathion sprays usually put an end to them, but once in a while I’ve had to resort to the solution of taking a thrip-free cutting and discard the main plant. Strangely enough, the thrip that is most susceptible to sprays isn’t the one that favors my plants! As I said earlier, I’ve got oat-thrips, and my County Agent tells me that the standard controls used by farmers are not designed for indoor use, so I’ve just had to put up with them, more or less, taking cuttings when the thrips get too plentiful, and waiting for cool weather when they disappear.

Aphids

Aphids are such a well-known pest that they probably need no description here, but for the sake of any novice gardeners who have never seen one they are about one-eighth of an inch long, red, gray, green or black, and stand quite erectly on their skinny little bow-legs. Their favorite dining-area is the succulent terminal growth of almost any plant, and of course their juice-sucking activities promptly put the plant on the sick-list. These are most plentiful in the summer, when they seem to ride indoors on the breeze (or on your clothes or on plants you bring in), but they can be hosed off into the sink or killed easily with a malathion or neem oil spray.

Springtails

No article on house plant insects would be complete without a few words on springtails. These are the terrifically-active little things that jump around excitedly when you water your plants, sometimes showing up in the plant-pot saucers in great numbers, or scurrying around on the sides of pots plunged in peat moss. For all the commotion they make, it would seem logical that they would do an equal amount of damage, but the truth is they are absolutely harmless. I don’t care for them, especially when they leap off a plant I’m using as a dining table centerpiece and get on the silverware or inch up the glasses! But springtails are a natural constituent of rich soil which has a high organic content, and they feed on the decaying vegetable matter, not on the live plant parts. However, if you want to get rid of them try neem or malathion.

Slugs

One more pest, not really in the insect classification, however, is the slug. These snails-without-shells always seek out the most prominent parts of your choicest plants for their foraging. However, during the daylight hours they love to conceal themselves under the pot-rim where they are easily found, once you suspect their presence (a slimy trail and chewed leaves means slugs). Just remove and squish in a piece of paper.

Remember, if you follow good cultural practices with your plants, you may never be troubled with any of these pests. Use that well-known ounce of prevention… it’s much simpler in the long run than any cure.

by K Walker

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