We're having a problem with flies i.e. fruit and sewer flies. Can't seem to get rid of them in our travel trailer. We've flushed and cleaned out the grey water pipes/holding tanks and all other drains i.e. sinks and shower with RID-X, BORAX and a DAWN dishwashing detergent. Additionally, we've been using either 'OXY-KEM Holding Tank Treatment' tabs or the liquid concentrate 'RV Toliet Treatment' about once a week after dumping the holding tank. We're very good about keeping a clean trailer with no food or dirty dishes out. Any ideas or recommendations? Thanks in advance.

How about setting off a bug bomb inside. Make sure all flames and any electrical are turned off to prevent ignition.Option is to keep a spray bottle of "all surface" cleaner handy and spray the flies as they fly around. Flies have a very short life span so if you can keep killing them eventually they are gone due to extinction.

Even though they are labeled "for outside use only", I still use the Hot Shot no-pest strips indoors. They are very good for keeping gnats, flies, and no see 'ums at bay.

The larvae live in the gunk on the pipes. In my case they were coming up from the shower drain and I have successfully used boiling water poured down the drain to get rid of them. Last summer they appeared and I had to use the boilng water twice to get rid of them.Once I had them in the black tank. I sprayed a bunch of insecticide in it through the toilet and that killed them.

We once had the flies in the black tank. Shut off the water and sprayed a generous quantity of Raid down the toilet. Closed the lid. Flies gone and never came back.

I saw a hint for getting rid of fruit flies. Take a plastic glass that you can toss and put a couple slices of banana or fruit in it. Cover it with plastic wrap and poke a small hole in the wrap. The flies get in and can't get out. I haven't seen a fruit fly since except in the disgusting cup.

Flies | Good Sam Community

mr__ed
Explorer
Aug 02, 2013
On those rare occasions when I had trouble with flies I've tried hanging fly paper at various places in my fiver. Quite unattractive and besides they didn't catch many flies. So, I wouldn't recommend fly paper. I've reverted to the good old fashioned fly swatter.
mtngal77
Explorer
Aug 02, 2013
All great advice. Thank you everyone very much!
CincyGus
Explorer II
Aug 02, 2013
bertnspike wrote:
CincyGus wrote:
1st, Keep your black and gray valves closed except for when actively dumping them. Never seen a fly that could swim.
2nd, Once you dump, go run hot water into your gray tank until you empty your hot water heater and it starts to run cold. Then dump again with the hot water. That should kill any that are in your hose or the bottom of the gray tank.
Third, Pour hot water doen your drains once in a while. Shower, Bathroom sinks, Kitchen sinks.

The larvae swim very well, I promise you. Professional exterminators will tell you that hot water is a temporary solution and will NOT kill the eggs and larvae.

If the only time my vaule is open, it's draining 20+ gallons of water and additives, I'm doubting any larvae have the power to swim upstream in that. Unless they are Salmon Larvae.......
down_home
Explorer II
Aug 02, 2013
Stayed at one campground off the Natchez Trace. It had big old slugs coming out of the sewer connection. Didn't connect. Expected to wash clothes but you should leave the gray open when you do. Next morning when we dumped there was a lot of soapy water to wash them down.
When we leave the gray open we usually have the washer cranked up shortly after and the hot soapy water and softner probably get most any fly larvae.
Close it when we are away from the coach though.
bertnspike
Explorer
Aug 02, 2013
CincyGus wrote:
1st, Keep your black and gray valves closed except for when actively dumping them. Never seen a fly that could swim.
2nd, Once you dump, go run hot water into your gray tank until you empty your hot water heater and it starts to run cold. Then dump again with the hot water. That should kill any that are in your hose or the bottom of the gray tank.
Third, Pour hot water doen your drains once in a while. Shower, Bathroom sinks, Kitchen sinks.

The larvae swim very well, I promise you. Professional exterminators will tell you that hot water is a temporary solution and will NOT kill the eggs and larvae.
bertnspike
Explorer
Aug 02, 2013
Clay L wrote:
You did a lot of stuff that ought to work but the water in the sewer line won't help. The larvae came up through the water in my shower trap and then turned into flies. As flies they may also be able to get into the tanks via the roof vent.

I know the larvae travel through water. My hope is that the ones that do get that far won't come out on the RV side and get in when I open the valves to dump. Probably meaningless, but can't do any harm. I zip-tied a bit of screening to the roof vent after my first run in with these guys.

Sewer gnats are NOT fruit flies. Putting out wine or bananas is a pretty good way to attract fruit flies IN ADDITION TO the sewer gnats. The sewer gnats will ignore it.
Clay_L
Explorer
Aug 02, 2013
bertnspike wrote:
SNIP

Then I hooked everything back up, starting with the sewer donut. I used my sewer hose support only on for the last 4 feet of hose, forcing a droop in the hose, which will have the same effect as a p-trap under a sink, in that it will stay filled with water, preventing any flies from coming up.

If you Google "sewer gnats" you'll learn all the juicy facts.

You did a lot of stuff that ought to work but the water in the sewer line won't help. The larvae came up through the water in my shower trap and then turned into flies. As flies they may also be able to get into the tanks via the roof vent.
CincyGus
Explorer II
Aug 02, 2013
1st, Keep your black and gray valves closed except for when actively dumping them. Never seen a fly that could swim.
2nd, Once you dump, go run hot water into your gray tank until you empty your hot water heater and it starts to run cold. Then dump again with the hot water. That should kill any that are in your hose or the bottom of the gray tank.
Third, Pour hot water doen your drains once in a while. Shower, Bathroom sinks, Kitchen sinks.
mobeewan
Explorer
Aug 02, 2013
Terro fruit fly trap
2gypsies1
Explorer III
Aug 02, 2013
If you're actually talking of fruit flies, this has worked great for us: take a cup and fill it half with wine (I know, what a waste), cover with saran or foil and poke a couple holes in it. You'll be amazed at how many you capture after a couple days. Now...if you're still brooding over that wine, the extra protein will do you good! :)

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