Bait it where it hides

Look at the size, and the people here give you a rule that works in most North American homes and, they warn, not everywhere. Across three separate conversations and several single accounts: a big roach — over an inch, often seen once, often where there's a leak — is usually an outdoor species that wandered in. It isn't living with you. A small roach — under an inch; the German cockroach, the tan one with two dark stripes if you check a picture — is the one, and one of those means more of those, because that species lives indoors, breeds fast, hides near food, grease and water, and cannot be cleaned away once it's established. One correction in these conversations adds a look-alike: the Asian cockroach is the same size and colour, but it can fly, which the German can't, and doesn't usually set up indoors, so a small roach that flew is a different, smaller problem. The big one isn't nothing either — one caution says a large roach seen more than once, especially somewhere it shouldn't be, is often a sign of a water leak behind an appliance, and that fixing the leak addresses the cause. Two things about what you see. If you see small roaches in daylight, one account who dealt with a bad case says that's a colony out of hiding room, and it's serious. And if you've never seen one but you're worried: switch the kitchen light on an hour after dark, as the try-this step says, and look before they run. Four cautions and an argument in these conversations say the size rule breaks down outside North America — in Australia, one account says, the ordinary outdoor roach is already big and the small ones aren't small — so if you live elsewhere, identify by the stripes and by whether you keep seeing them, not by the inch. And one account's rule for the borderline case: if it's exactly an inch, treat it as the indoor kind to be safe; nobody measures one before killing it.

Poison they carry home, not poison you spray at them, and the reason is worth understanding. A spray kills the roach you can see and nothing else; the pesticide information service's guidance is that repellent sprays drive roaches away from an area and can spoil bait laid near them, so a sprayed kitchen is a kitchen where the bait stops working — that line is the regulator's, not these conversations'. What works is something slow. Three separate conversations use boric acid, and four describe why it spreads: a roach walks through a barely visible film of it, carries the dust on its body back to where the others hide, and dies over a few days — and roaches eat their dead, so the poison passes on. One correction here is fair: roaches don't have a colony with a queen the way ants do, so there's no nest to wipe out in one blow; what you have is a crowd sharing hiding places, and slow poison reaches the crowd. The how, from four single accounts and the cautions attached to them: it must be a film you can barely see, not a line or a pile — roaches walk around piles — puffed from a bulb into cracks, along baseboards and corners, and under appliances. Left alone, not swept, for a week or so. It is boric acid, not borax; two corrections and several cautions say people buy the wrong tub. And it is not as harmless as some accounts here claim: the safety note at the top says why, and the plain version is that it stays out of reach of children and pets or it doesn't get used — an argument in these conversations puts one side on open-floor dusting and the other, with the parents of toddlers and the owners of cats, on enclosed placements and bait balls only, and this page is with the second side. Two conversations, and several single accounts, prefer a gel bait — for exactly that reason: easier to apply and less messy than powder, and nothing on the floor. One account who cleared a severe infestation used gel bait together with a growth regulator, which stops eggs hatching, and calls that combination highly effective. Two things about diatomaceous earth, which several accounts use: it isn't a poison but a very fine abrasive dust that scratches the insect's waxy coat and dries it out; it stops working when wet; it's the food or garden grade only; and one correction says it doesn't spread through the crowd the way boric acid does, so it's a helper, not the main tool. For the roach in front of you right now, two accounts spray it with soapy water, which stops it faster and more reliably than squashing, because the soap blocks its breathing; and one person's trick is the one this page is named for — don't kill the first one you see, watch where it runs, and put the bait there. What doesn't work, from the people here: bay leaves (one person found roaches sheltering under them), and the baking-soda-and-onion recipe that's supposed to make them 'explode' — the people here treat the popping as a joke, and baking soda isn't boric acid.

Because they may not be yours. Three separate conversations, and three single accounts, describe the same discovery: a spotless flat with a persistent problem, and the source is the unit next door, or below, or a shared wall or pipe run. One account says the whole building had them and no single tenant's effort could hold; another brought them home in cardboard boxes from a storage unit. Two things follow. First, cleaning is necessary and not sufficient: one caution says plainly that an established German roach problem needs bait, not just a scrubbed counter, so clean and bait, don't clean instead. Second, treat the routes. Four separate conversations say roaches come up through drains and in along water leaks — keep sink and floor drains stoppered overnight, fix the drip under the sink, dry the space behind the washing machine — and one person's whole method is caulk: every crack along the skirting, every gap around pipes where they pass through the wall, mesh over vents, so the neighbours' roaches have no road. If the problem is coming from next door, one caution notes you may go through a whole jar of boric acid spreading the poison far enough. Then the part about landlords, which the people here in flats care about. Several accounts say that in shared housing the problem is the building's, not yours, and that treating one unit while the others go untreated is a treadmill; one account with a badly run building says the housing authority, a housing charity or a local news desk was more use than direct legal action, and another says that in many places a landlord is obliged to deal with pests in a rented home — check your lease and your local rules before you pay for a service yourself. That is also where the argument at the bottom of this page lives: whether to pay a professional or do it yourself. Two conversations say exterminators charged hundreds for the same bait you can buy, and did it badly; other accounts say a good one was cheaper than expected, used products you can't buy, and got it done in a way a nervous first-timer with a tub of powder didn't. Both are on this page. Two smaller honesties from single accounts: a large roach seen more than once is a leak until proven otherwise; and the long-legged house centipede you also just saw is on your side — it eats roaches — unless there are enough of them to be their own problem.