Keep the pests away from your house­plants

Con­trol ‘scale in­sects’ in­doors

The Covington News - - Agriculture & Outdoors - By Lee Re­ich

Is your floor or furniture feel­ing sticky th­ese days? That could be a sign of an in­sect pest on your house­plants, one that you’d hardly no­tice oth­er­wise.

That sticky stuff is a sug­ary “hon­ey­dew” se­creted by so-called scale in­sects, who typ­i­cally start mul­ti­ply­ing faster and faster as spring ap­proaches.

The sus­pects

Even star­ing right at your house­plants, you’ll have trou­ble find­ing the cul­prits.

Look for noth­ing more than an oc­ca­sional shiny, brown bump about an eighth of an inch across. They’re es­pe­cially hard to see on bark, and es­pe­cially with nat­u­ral bumps, such as cherry tree bark. (Out­door plants also may be at­tacked.)

Flick at a bump with your thumb­nail to tell whether it’s sup­posed to be there; scale in­sects come off eas­ily. Ig­nore scale long enough and you may soon no­tice brown bump upon brown bump of scale in­sects piled up next to each other.

By then, of course, you’ll also no­tice that leaves have wilted or yel­lowed, per­haps even that the plant has died. Or your feet might stick fast to the floor as you try to walk by.

Hum­drum life

Let’s of­fer scale in­sects some sym­pa­thy for the drab lives they lead. Af­ter hatch­ing from eggs or be­ing born live, the ba­bies crawl around for a few hours or days un­til they find a place on a plant to settle down.

There, they sink their mouth­parts into the plant and start suck­ing. And that’s about it for many fe­male scale in­sects: A few hours or days of walk­ing around, find a place to eat, then stay put for the rest of your life.

You’d think that the adult males, hav­ing wings, might have a bit sparkle in their the lives. Hardly. Th­ese males don’t even eat. They just fly around and mate — but for only a few hours — then die.


Sym­pa­thy aside, that stick­i­ness and those yel­low­ing leaves are re­minders that this pest must be con­trolled.

And con­trol isn’t easy be­cause of the pro­tec­tive shield — the scale — th­ese in­sects grow over their bod­ies. The pro­tec­tive shield also pro­tects the ba­bies — un­til they crawl out.

And that’s a good time to get them, us­ing var­i­ous types of sprays. Var­i­ous plant-ex­tract oils, as well as spe­cially re­fined pe­tro­leum oils, can be ef­fec­tive. Use a dor­mant oil on leaf­less plants, a sum­mer oil or su­pe­rior oil on plants in leaf. In­sec­ti­ci­dal soap also works against scale in­sects.

Hand-to-hand com­bat is an­other approach. Use your fin­ger­nail to flick scale off, or a cot­ton swab dipped in al­co­hol to rub down in­fested leaves or stems. Dis­lodg­ing a scale in­sect breaks its mouth­part so it can never feed again.

Sprays or dis­lodg­ing need to be re­peated ev­ery week or two in or­der to catch young that crawled out from un­der their pro­tec­tive cov­er­ings since the last treat­ment. You can buy nat­u­ral par­a­sites and preda­tors to keep con­tin­ual tabs on scales in­sects, but they are more ef­fec­tive in green­houses.

Pre­vent it

The sec­ond eas­i­est approach for a plant that is thor­oughly in­fested is to just dump it. Dif­fer­ent kinds of scale in­sects are some­what finicky about the kinds of plants they at­tack, but why risk spread­ing con­ta­gion from a heav­ily in­fested plant to your other plants?

And the best way to con­trol scale, with house­plants at least, in­volves noth­ing more than mov­ing the plant out­doors in sum­mer. There, some com­bi­na­tion of en­vi­ron­men­tal con­di­tions and/or nat­u­ral preda­tors and par­a­sites of­ten knock back scale in­sects — un­til au­tumn, at least.

Take care: in­sects.

Pro­tect your inside plants from at­tacks by scale

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