Fruit Flies

I hope you all had a wonderful Thanksgiving!

Bed Bugs were discussed at-length around the turkey here in Central New York. In a few weeks, I will post December’s newsletter article: how to prevent bringing bed bugs home from the holidays!

Perhaps the grateful group should have discussed a more pressing threat to those with leftovers from a family feast: Fruit Flies. I hear many small flies referred to as fruit flies…because a few types of flies will buzz around rotting fruit. Technically, the common name for today’s star is the Vinegar Fly.

Prevention is the best type of management, so if you haven’t done so already: consume, contain, or compost all that filled your cornucopia. I realize most residents don’t compost, but the alliteration was hard to resist…and chuck seems so wasteful.

If residents report “fruit flies” here’s what you do…

1. Inspect and identify

The adults are tiny (1/8”), but are easy to spot because they like to sit on the fruits and veggies they deem suitable for a nursery. When disturbed they will fly, but they prefer to be grounded. A noticeable characteristic of many adult Vinegar Flies is their red eyes. This isn’t set in stone though, they may have black eyes. During your inspection, make note of where there are a lot of them, this is your best clue for solving this pest problem.

Further investigation can lead to their source: some rotting fruit or veggies, the accumulated sludge that sticks to the bottom of the garbage can, bottles and cans that didn’t get rinsed, a mop that didn’t dry out, the "gelatinous scum" that builds up inside of drains, and the drain pan under a refrigerator. There should be lots of adults near the source, but more importantly: maggots! A maggot is a fly larva and its purpose in life is to eat goo, pupate (like a caterpillar going into a cocoon) and emerge as an adult Vinegar Fly. You may see the pupae (little horned packages) stuck near the goo where the maggots are doing their thing.

2. Determine if action is necessary

If you’ve found Vinegar Flies, you’ve probably found their source too—if not, keep looking. If you find a good breeding site where they’re flying around, action is necessary. Vinegar Flies do not bite humans but most people don’t want to live with them around. And as so many pests do, they indicate an underlying problem—rotting is not sanitary.

3. Plan treatment and take action

Cultural control: Vinegar Fly control is almost all about cultural control—cleaning! Sometimes finding and throwing out one piece of fruit will solve the problem. Focus efforts around where you find the flies, but while you’re at it, clean up all potential breeding sites too. If you think the source is the sink drain or trash compactor, check out the recommendations I gave in this section of my post on Drain Flies.

Mechanical control: The infestation won’t be stopped until you take away the spots where the flies are laying their eggs, but while you’re playing detective and maid, a trap can be constructed to capture adult flies. Create a paper funnel by rolling a piece of paper and securing it with a piece of tape. Place the funnel into a jar that contains a small amount of apple cider vinegar or red wine in the bottom. Instructables has a how-to on this process (but skip the hot glue gun & go for tape instead).
(Thanks to TX entomologist Wizzie Brown for this advice. Check out her blog at: http://urban-ipm.blogspot.com/2010/11/fruit-flies.html)

Biological Control: Finally a household pest for which we have biological control! If the source is hard to reach (drains, deep in cracks or crevices, etc.) Use a foam enzyme cleaner or microbe product that rapidly biodegrades the organic matter in the drain. These cleaners contain the stuff in nature that breaks down organic matter—the application just helps along the process. If you don’t know how to get a good cleaner for Vinegar Fly control, ask your PMP. Note that using harsh chemicals like bleach or a drain unclogger will make these natural cleaners not work. As always, follow the label!

Chemical Control: Pesticides aren’t usually needed for Vinegar Fly control and do not get at the underlying source. If your PMP recommends pesticides for Vinegar Flies, question him on whether non-toxic alternatives would be better both in terms of exposure to pesticide and sustainable control.

4. Evaluate effectiveness

If residents are still reporting these pests, keep cleaning daily. If the flies are gone, keep cleaning on a regular schedule and store food items so that pests can't get to them. Sanitation is the foundation of structural pest control.

Thanks to John Gideon of General Pest Control Co. in OH for his insights. I also got some information from the factsheet produced by the University of Kentucky.

Comments

[Allie]

From Sam Bryks in Canada:

Very happy to see there is no mention of any pesticides in the article. A few interesting things about these creatures: one of the reasons they are called vinegar flies is because of their prevalence in vinegar fermentation as the larvae actually thrive in concentrated vinegar! They crawl up the sides of the huge high barrels and pupate on the surfaces. But of course, they love any kind of fermenting item—a bit of dropped fruit, or spilled juice- even moist bread...that has fermented.

A bit of caution about enzyme or bacterial drain cleaners... enzymatic cleaners are corrosive as they break down organic matter, so caution is key and the bacterial cleaners are live bacteria and althought not strictly speaking, primary pathogens, they can be facultative pathogens, and a splash in the eyes is not a good thing. Both of these are fairly slow acting. Some oxy household cleaner that is peroxide based is not bad, and a bit of mechanical action with a "snake" type of instrument is good too.

For apartment buildings the drain cleaning is a building maintenance issue. For homes or townhomes, unless there is a fair organic load, it is not usually a huge issue, but as noted in the article, cleaning of moist areas is key.

[Carolyn Seely]

Hi
I live in apt of old building. 4 apts upstairs 3 business down. We have a horder in an apt. The beer cans, animal waste, old food in knee deep. The rest of us are clean we are all complaining about fruit flies. Can this apt be the cause or source , like they come out of that apt or seep thro n friut flies throughout the whole building?? Thank you for your input

[Susannah Reese]

Hi Carolyn, I don’t believe fruit flies can travel that far (from apt-apt) but depending on the construction of your building (connecting vents etc) it’s possible.
Here are some tips:

1. don’t leave any produce out on the counters. If you're in the north cooler temps are coming and fruit flies numbers will drop. Can you keep fruits and veggies in the fridge or enclosed some how?
2. They even can breed in the gunk that collects in the drain. Clean the drain catcher regularly. (there are such things as drain flies, and phorid flies that can breed in drains. these would take other control measures so make sure what you are seeing is actually fruit flies.
3. Keep a bottle of soapy water on the counter. Whenever you see them flying around, spray them. Sometimes I take the vacuum hose and suck them up.
4. Make a trap. Put a piece of fruit in a cup (juice or vinegar work too). And make a funnel out of paper. Put the small hole side down and tape to the edge of the cup. The flies will go in but won’t figure out how to get out. Dispose of the flies that you collect or spray them with soapy water. Search the internet for a DIY fruit fly trap so you can see what I’m talking about.
5. I've found some banana scented sticky cards but i don't know where you would get those. you can always buy the sticky cards they make for houseplants and place them where you see the most fruit flies. you can even place a small piece of fruit on the card to attract them.

There’s some other concerns in my mind with a hoarding neighbor but it may be beyond what you can do. Cockroaches would be a bigger concern. If I were you I would buy some cockroach sticky traps to monitor. Put them under the sink and against walls in the dark corners of your kitchen. it’s best to be on top of a cockroach infestation early. Let me know if you have questions on any of this.
Good luck with the fruit flies.
~Susannah Reese, StopPests in Housing