I have had a bad fungus gnat problem, I originally ordered nematodes back in January from Nemaglobe on amazon, but they froze in the post and died. Dont buy them if they might freeze in transport.
So I ordered some Stratiolaelaps predatory mites from GrubGrenade on amazon. I got there smallest size pack and thought I would count out the required 25 mites per sq ft using a pair of magnifying goggles and a small artist paint brush, which took me 2 hours. I could not find the 500mites only 180 odd so I sent Grub Grenade an email saying I was short of mites. I got a reply back in 6 hours, advising how to count them properly, which is not possible for me to do, they said they are there but you just cant see them, but they also said, that they would be happy to send me some more, to make sure I was happy. I received the next size up package of 5,000+ mites 2 days later. That’s Great customer service as far as I am concerned.
I replied to the email I was sent, as I had been asked some questions of what I had already tried to treat the gnats with. I got back some good info that may be of interest to other growers on nematode and mite use.
Grub Grenade.
The thing with nematodes, is even if they do arrive healthy, they do not give longterm control. We rarely recommend using them in the Biocontrol industry, and the only time we do is when there is a severe infestation of fungus gnats or other soil pests, to use them as a knockdown before using these Stratiolaelaps mites.
For a big grow area, this is a more economical option than buying tons of Stratiolaelaps, where you can use nematodes, cheap, to get the pest numbers down and then use Stratiolaelaps at a lower number, which also feed on the remaining nematodes which will boost the Stratiolaelaps population even more. The Stratiolaelaps will then persist in most growing conditions, where the nematodes require a narrow temperature and humidity range to exist/cycle, which is often for short periods of time in most growing situations. The mites just go sluggish in cold temps unlike non beneficial mites that go dormant. These predatory mites will hunt down sleeping spider mites, and eat them as well as their larvae, and eggs.
Nematodes are very easy to produce in massive numbers and can be applied to crops similar to a pesticide, so they are still widely used and embraced by growers. This is really the main reason The Grub Grenade exists. To get Stratiolaelaps mites to people who are frustrated with nothing really working for fungus gnats. Though it is more expensive than nematodes at first, the efficacy and persistence quickly pays for itself, and then soon later makes it the best bang for the buck.
Stratiolaelaps mites are sometimes advertised to be applied twice. The second time a couple weeks after the first application. This is not true, and if it is necessary for their Stratiolaelaps, it means the product has been stored for a long period of time in the container and the population of mites has been compromised, in that they have run out of food and have began to cannibalize, which means the females eating the young males, so you end up with a huge population of adult females which not so many eggs and males.
So a subsequent application a couple weeks later will help that product be effective. We package the same time that we ship, same day, and use fast shipping, so our product is always “fresh”, sexually balanced, and only needs the one application.
In most situations, like indoor plants, one application really should be all that is needed for multiple years, if not indefinitely. Even some outdoor applications, like lawns to control some types of grubs, like weevils, we have had reports that about 5 years with one application is achieved before the Stratiolaelaps population is thinned out too much and needs to be reapplied.
At a Christmas Tree grower in Southern Quebec, Stratiolaelaps was used as a trial for their black vine root weevils, and two years later there was a noticeable absence in root weevils, so they dug out the soil and found that Stratiolaelaps was still there, in high numbers, from the original application. 5 years later they still didn’t need to reapply.
They’re native in most of the world actually, and are mass produced in almost every 1st world country. We are linked to Applied Bio-nomics Ltd., which is Canada’s largest insectary and the first company to produce Stratiolaelaps (they received the original culture from Ag Canada), which we are located nearby and purchase from daily.