Fruit Fly Control in Wauwatosa, WI: Check the Fridge Drain Pan Before You Spray

What to look for

The fly in a Wauwatosa kitchen is Drosophila melanogaster, about 1/8 inch with a tan body and red eyes per Texas A&M AgriLife. Wisconsin Horticulture reports the complete life cycle can finish in eight to ten days, so a population rebuilds between one weekend and the next, and killing adults without finding the breeding site accomplishes nothing. Wauwatosa's climate compresses the season. Summer highs near 82F and 72 percent humidity keep every bin, rag, and drip pan fermenting from July into October. Then winter lows around 16F end the outdoors, and the only flies left are the ones breeding in a heated house. The breeding sites are the part people get wrong. Wisconsin Horticulture tells homeowners to check trash can bottoms, refrigerator drain pans, recycling bottles, soiled mops and rags, broken drain traps, and leaking pipes around beverage dispensers. In a Wauwatosa house, old or newly renovated, the fridge drain pan collects fruit juice and defrost water in the dark and is almost never pulled. A basement drain with a cracked trap is the other classic hidden source. Outdoors, spotted wing drosophila was first reported in Wisconsin in 2010 with breeding populations by 2012. It produces a generation in as little as eight to nine days and a female lays more than 300 eggs in roughly two weeks. It attacks sound berries on the plant, so it is a garden matter, but berries picked ripe can carry larvae into the kitchen. The state's 19,100 acres of cranberries add a large pulse of fermentable fruit to the same fall weeks when indoor numbers peak.

• 1Tan, red-eyed flies hovering over farmers market peaches or a basket of garden tomatoes in late August.
• 2A few flies rising out of the disposal or sink drain as the morning dishes start.
• 3A sour smell from the bottom of the trash can or the recycling bin after a humid week.
• 4Flies gathering around the base of the refrigerator, a sign the drain pan underneath is fermenting.
• 5Small brown pupal shells stuck beneath the counter lip or on the baseboard behind the trash can.
• 6Backyard raspberries that soften and leak soon after picking, which can mean spotted wing drosophila larvae inside.
• 7Flies that vanish after a spray and are back within days.

Treatment options and typical costs

Prices are typical published ranges. Ask what’s included before you compare quotes.

Wisconsin Horticulture's list, and why the fridge drain pan is on it.

The trash can bottom is the same idea. Peels and juice slip past the bag and pool under it. The recycling bin holds beer, wine, and juice residue that ferments in 72 percent humidity within days. A provider working a Wauwatosa home should go through this list in order before anything else, because the state's own guidance says spraying adults without clearing these sites accomplishes nothing. If the flies persist after the list is clear, the drain traps come next. Wisconsin Horticulture is blunt that the only way to completely stop problems with fruit flies is to find and eliminate breeding sites, and its list of places to check is more specific than most: trash can bottoms, refrigerator drain pans, recycling bottles, soiled mops and rags, broken drain traps, and leaking pipes around beverage dispensers. The refrigerator drain pan deserves its own explanation. It sits under or behind the fridge, catches defrost water and whatever drips from the produce drawer, and stays dark, warm from the compressor, and wet. In a Wauwatosa kitchen in September, with peach juice and tomato seeds finding their way in, it is a nursery nobody sees. Pull it, wash it with hot soapy water, and check it monthly through the fall.

A fruit fly calendar for Wauwatosa.

Raspberries ripen, and spotted wing drosophila, breeding in the state since 2012, starts laying in them. August through October is the peak. Farmers market peaches, garden tomatoes, and apples arrive together, and 72 percent humidity keeps every spill wet. Statewide, the cranberry harvest sends 4,605,000 barrels through handling and processing in the same weeks, a reminder of how much fermentable fruit moves through Wisconsin in the fall. November tapers with the first hard freeze. Anything still flying after Thanksgiving is breeding inside, and the fridge pan is the first place to look. Wauwatosa's fruit fly year is quiet for most of the calendar and intense for three months. December through March, winter lows near 16F end everything outdoors. Indoor flies in that stretch come from an indoor source, such as a broken basement drain trap, a soiled mop, or a fridge drain pan that has not been pulled since fall. April through June warms slowly. More bottles and cans in the recycling make the bin the first thing to watch. July pushes kitchens toward the 82F summer highs, and Wisconsin Horticulture's eight to ten day cycle hits its pace.

Fruit flies in an older Wauwatosa basement.

The test is clear packing tape over the drain overnight; flies on the tape confirm it. The fix has two parts. A plumber repairs or replaces the trap, and then an enzyme product digests the film that built up. Pouring water into the drain monthly afterward keeps the seal full. A laundry sink with a slow drain and a leaking supply line gets the same treatment. The University of Maryland notes larvae crawl to a drier spot to pupate after feeding, so pupal cases may show up on the basement floor or shelving away from the drain. A provider checks those areas too, because they confirm the drain has already produced at least one generation. Wauwatosa dates to 1835, and if your house has a basement, its plumbing may hold two items from Wisconsin Horticulture's breeding site list: broken drain traps and leaking pipes. A trap is the U-shaped bend that holds water to seal a drain. When it cracks or dries out, organic matter collects where water should be, and in a heated basement that mix ferments year-round. The signs are consistent. Flies in the basement or coming up the stairs in winter. A faint sewer smell near a floor drain. Flies that persist after the kitchen list is clear.

What affects the price of fruit fly control in Wauwatosa homes.

A Wauwatosa home near the $315,000 median that has a basement floor drain, a laundry sink, and original traps has several stops, and each one needs a tape test and possibly a repair. Houses converted to apartments share a stack and may need every unit treated together. Food businesses pay more for the beverage dispenser inspection, since leaking pipes around those machines are a named breeding site, plus the monthly drain program and the written log. Season matters too: a September call during the produce and cranberry peak can mean a population spread across several sources. Ask each provider to price the inspection separately from follow-ups, say how many drain treatments are included, and state what they do if the flies are drain flies or phorids rather than fruit flies. For Wauwatosa homes, the first thing that moves a quote is where on Wisconsin Horticulture's list the source turns out to be. A provider who finds a fermenting fridge drain pan and an unrinsed recycling bin, leaves the checklist, and schedules nothing is a short visit. One who finds a broken drain trap in the basement, refers you to a plumber, and schedules enzyme treatment for several weeks afterward is a program. Your own house drives that.

How to compare two fruit fly quotes in Wauwatosa.

Does it include checking drain trap integrity in the basement, or is that a separate call? Ask both what they would do if the flies turn out to be hump-backed phorids that run before flying. The right answer involves a plumber and a moisture check, not more aerosol. Then ask about traps. A provider who sets the state's banana, pear, or wine jar under a funnel to locate the source and catch stragglers is following the same guidance you can read yourself. Finally, for a cafe or cafeteria kitchen, ask whether the quote covers inspecting every beverage dispenser for leaks, since leaking pipes around those machines are a named breeding site on the list. Start with whether each provider named the breeding site. Wisconsin Horticulture's guidance is that killing adults without finding the site accomplishes nothing, so a quote for a Wauwatosa kitchen that lists spraying but never mentions the fridge drain pan, the trash can bottom, the recycling, the mops, or the drain traps has not looked. Next, compare what is included. One visit with the state's checklist, or a series of enzyme treatments? Does the price cover a return visit if flies persist past the eight to ten day cycle?

Simple ways to keep fruit flies away

• Pull and wash the refrigerator drain pan monthly from July through October, since Wisconsin Horticulture names it as a breeding site.
• Scrub the bottom of the kitchen trash can weekly, because juice and peel residue pools there unseen.
• Rinse every bottle and can before recycling and take the bin out twice a week in summer humidity.
• Wash mops and rags and hang them to dry rather than leaving them soiled in a bucket.
• Pour water into basement floor drains monthly and have a cracked trap repaired, since a broken trap breeds flies all winter.
• Refrigerate farmers market peaches and garden tomatoes the day they ripen, as Wauwatosa kitchens run the cycle at 8 to 10 days.
• Harvest backyard raspberries and cherries as soon as they ripen and strip any overripe fruit from the canes and branches.
• Close blinds at night in late summer, since fruit flies pass through screens toward kitchen light.

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