Spider Mites or Amblyseius Fallacis?

[sinky]

I wish I could post the pics from my microscope. I was checking the plants this morning and saw a bunch of fat little bugs (smaller that an average speck of sand) crawling around the soil. I took a teaspoon of sand, put it on a plate, isolated one of the buggers from the sand particles, put the plate in the toaster oven until it stopped crawling, then put him under the scope. What I found made me think spider mite. I threw some loose leaf tobacco on top of the soil (actually on top of the 1/2" of sand I used to get rid of my fungus gnats), and sprayed with enough rubbing alcohol to saturate the top 1/2" of sand. I took one more of the buggers that was a little more mature, and decided that maybe it looked more like Amblyseius fallacis, a predator of spider mites. They all look so alike, though. I hate to do this, but I think the only way to be sure before I take further action is to wait till I see webs.

So whats the opinion, folks? Do you think I should wait till I see webs, or start with the tobacco juice, suds, pepper spray, neem oil, etc. pronto?

[stinkyattic]

You'll rarely if ever see spider mites anywhere near the soil surface- they prefer to live their entire lives high on the plant, basking in the heat of the bulbs, and laying eggs under the upper leaves.

You may wish to pyrethrin-bomb the grow room twice (3 days apart) to kill whatever pests you DO have.

[sinky]

I would be too scared to do one of those things now, a few weeks into flowering. I understand that it leaves no residue, but I'm irrationally scared when it comes to chemicals.

[stinkyattic]

To treat just the bugs on the dirt, a sprinkling of diatomaceous earth should do 'ya.

[psteve]

Get yourself a Hot Shot No Pest Strip.
It will take care of your problem.
No spray, no residue. Just gas as the strip biodegrades.
Just be sure to vent your room before entering.

[Mr. Clandestine]

Granny (StormCrow :hippy:) made a post the other day where she recommended adding sand to the top of the pots to prevent fungus gnats from breeding there. Would this be feasible for other soil pests? She also mentioned adding about an inch of it... how would that affect the roots and medium as it eventually drains into the pot?

[sinky]

I had fungus gnats like you wouldn't believe in my legal indoor garden in my house. I treated my cannabis as though it had an infestation just for good measure. I will say, though, that sand works wonders. Calling the problem an infestation would almost be an understatement. My sticky strips were probably catching about 10/hour when they were fresh. After about 2 weeks, they were saturated with no more stick surface left for more gnats. At any given time, each pot would have about 4 gnats per sq inch crawling around; really ridiculous.

I ran out of fly traps just as I decided I was going to lose all my plants if I didn't take action. I therefore got more sticky strips, but the night before I did that I covered all my soil surfaces with about 1/2" of sand. The next day when I set out the new strips, there was hardly a gnat in the air, practically no gnats on the leaves, and I wouldn't get a swarm crawling out of the soil when I watered. The fly traps half only been catching 3 or 4 per day since I added the sand about 5 days ago. We'll see how things work in the long term, but I think the sand pretty well put the brakes on their life cycle.

[sinky]

Boy oh boy did they come back. Sand is still in place but in the last couple days they have come back in droves. Better get some pest spay (for the ornamentals) and tobacco (for the herbs).

[stinkyattic]

Diatomaceous earth doesn't DETER them, it abrades the hard exoskeleton so the pest dehydrates rapidly and then dies. Get some DE if you want to spread anything on the soil surface. Really. Sand doesn't do a thing, and if it's not washed, can add salt to your soil.

[sinky]

goodness I should do that, and probably will. I just cringe, though, every time I have to make an online order for garden supplies.

Say, stinky -- do you think that fungus gnats could live off decaying terra cotta? The bulk of these devils seems to lie in my umbrella tree's pot. It is notable I think that portions about a half cm in diameter have entirely fallen away from the pot as the moist bits of clay seem to resemble soil now, more than pottery. I doubt they could feed on degrading earthen material, but I guess I'm not sure.

[stinkyattic]

Degrading clay will hold moisture very well and give them the wet environment that they like. Can you put a grid in the saucer, like a round cookie drying rack, under the pot so that there is even a little air flow underneath to dry it out more?
You can get diatomaceous earth at home depot or even walmart in the pest control section. Garden centers and farm supply shops carry it too.