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So today is an indoor day at work. I work in a couple of office towers, but I'm speaking right now of one particular, which is a 4 hour account (4 floors) and has ...fungus gnats. These are a pest that pupates in the soil, doesn't hurt the plant, but flies around in the adult stage and annoys clients.
My boss has been in the indoor hort industry for 30 years. He's never seen a case of fungus gnats this bad. Last week we treated the soil with predatory nematodes which should eat all the larvae and thus fix the problem.
Here's the issue: fungus gnats only live in the top 1/8" of soil, and they only live in wet soil. This account has had them since I got it in the early spring, and it's a dry account-- everything goes dry constantly. I've been keeping it on the bleeding edge of dryness anyhow, to combat the fungus gnats, and still they come (this means I have to be extra good at predicting things cause I'm not leaving a water buffer in the soil if we have an extra hot day or something like that). So there should be no way for these bugs to be in the account, but there they are, in droves.
So the likely thing that's happening is that a floor up or a floor down there's a business which either does its own plants, or hires the bottom-of-the-barrel large company which I shall not name to do their plants, and keeps them overwatered because it's a dry account and they're scared of wilting and just not good at knowing how to do it right. Then the bugs are going through the HVAC system, through the stream of air which vents up and down from office to office just inside the windows. They're accumulating on the floors above and below, flying around and annoying the clients, but not living in the soil (I've looked-- that soil does appear clean).
So we put in predatory mites, but I don't expect it to do much good. It does mean I need to keep the soil moist for the mites, though, instead of letting things go dry-- the gnats have a life cycle of about six weeks, so they'll be hovering around for that long regardless, and waiting to lay eggs in the soil as I'm keeping it moist. So this is kind of a weird solution, but we have no others.
My boss has been in the indoor hort industry for 30 years. He's never seen a case of fungus gnats this bad. Last week we treated the soil with predatory nematodes which should eat all the larvae and thus fix the problem.
Here's the issue: fungus gnats only live in the top 1/8" of soil, and they only live in wet soil. This account has had them since I got it in the early spring, and it's a dry account-- everything goes dry constantly. I've been keeping it on the bleeding edge of dryness anyhow, to combat the fungus gnats, and still they come (this means I have to be extra good at predicting things cause I'm not leaving a water buffer in the soil if we have an extra hot day or something like that). So there should be no way for these bugs to be in the account, but there they are, in droves.
So the likely thing that's happening is that a floor up or a floor down there's a business which either does its own plants, or hires the bottom-of-the-barrel large company which I shall not name to do their plants, and keeps them overwatered because it's a dry account and they're scared of wilting and just not good at knowing how to do it right. Then the bugs are going through the HVAC system, through the stream of air which vents up and down from office to office just inside the windows. They're accumulating on the floors above and below, flying around and annoying the clients, but not living in the soil (I've looked-- that soil does appear clean).
So we put in predatory mites, but I don't expect it to do much good. It does mean I need to keep the soil moist for the mites, though, instead of letting things go dry-- the gnats have a life cycle of about six weeks, so they'll be hovering around for that long regardless, and waiting to lay eggs in the soil as I'm keeping it moist. So this is kind of a weird solution, but we have no others.
