Garden Q&A

Strong pesticides will eliminate pests' predators, too

For The Baltimore Sun
Using a strong pesticide may be counterintuitive to controlling aphids.

I have aphids on my sedum each spring and have tried everything and can't get rid of them. I've been fighting this problem for years. What can I do?

Aphids are usually kept in check by their many enemies — predator insects such as lady beetles. You do not mention what steps you have taken to combat aphids, but it's possible that a vicious cycle has resulted from using highly toxic broad-spectrum pesticides. Strong, wide-ranging pesticides kill predator insects along with the targeted insects. When a small outbreak of aphids is handled with strong pesticides, the aphid population rebounds quickly, while the predator population takes longer to build up. The result is another aphid overpopulation. Horticultural oil, or even a strong spray of water, handles aphids well enough while you wait for your predator insects to finish them off.

We're finding teensy bugs in the carpet and a few on the wall of a spare room. They look like miniature lady bugs, about the size of Lincoln's ear on a penny. The room is unused, so it stays clean. We found fuzzy worms, too. Are they related? What are they doing there?

You have varied carpet beetles, which are mottled (there is also a black kind). This scavenger insect feeds on organic debris such as lint, pet hair, food crumbs and dead insects. The "fuzzy worms" are the species its larval stage, which molt several times before turning into beetles. The light-colored shed skins are a noticeable sign of carpet beetle infestation. You can control carpet beetles primarily through prevention, by thorough vacuuming of carpets, along baseboards, under furniture and in closets. While doing this, you may be surprised how many insects, especially stink bugs, have entered your house to overwinter and then died. For more tips and photos, search "carpet beetles" on the Home and Garden Information center website.

Plant of the week

Shamrock

Oxalis regnellii

Faith and begorra! Think St. Patrick's Day and beyond for enjoying delightful shamrocks. Oxalis species occur in many forms (some of which are lawn weeds; the real shamrock is a type of clover), but this houseplant provides year-round white flowers nestled among stunning trifoliate leaves, sometimes backed with iridescent purple. Give it bright, indirect light, even full sun in winter. Normal indoor temperatures are fine, though cooler nights prolong growing and blooming. The shamrock enjoys summer outdoors. Keep moisture levels even when it's growing, but reduce watering when not blooming or growing to allow it to rest. If it loses its foliage, be patient; store the bulbs in a cool, dry place then return it to a sunny spot when green shoots reappear. In dry conditions, mist it to prevent spider mites.

—Lew Shell

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Send in your gardening questions

University of Maryland Extension's Home and Garden Information Center offers free gardening and pest information at extension.umd.edu/hgic. Click "Ask Maryland's Gardening Experts" to send questions 24/7.

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