coffee as a natural insect killer??

i was reading a paper stating that coffee can be a great organic pesticide has anyone used it in this way?? this grower claimed to use coffee when watering and foliage feeding but not on mj plants so does anyone know if it would be harmful to mj plants?? i probably have gnats im trying to find the organically safest and most effective way of getting rid of them bastards so do u peeps have any other suggestions??

Pyrethrum made of Chrysanthemum Flowers. It kills on contact from the larvae to adults.
Pyrethrum by itself could get the job done, but most likely a few pests would get away and burrow into the soil to reproduce and start your problem all over. It only takes one female Thrips to survive and she can reproduce on her own w/o a male, aint that some shit! What an evil bitch. With thrips, gnats, and aphids the soil or medium needs to be treated also, Pyrethrum in large amounts will kill plants, so it is best to only use it where neccesary and apply lightly. On smaller plants a rinse may be needed the folowing day if the leaves are getting wrinkled badly.
Mosquito Dunks (aka Bacillus Thuringiensis). Dunks are intended for killing mosquito larvae before it matures. The larvae think the Bacillus Thuringiensis is food, but once they digest it it kills them. Not only does this work on Mosquito larvae, but Thrips larvae, Aphids, Gnats, and much more!!!
Mosquito dunks can be used every watering, and are completely safe for plants so going overboard on dosage is not a big deal at all.

this was written by a member named CustomHydro, and copied and pasted.
Here is his thread:
Guaranteed Cure for Thrips + other pests! All Natural! - Marijuana Growing

thanks bro i had already seen your posts in the bugs section!! as all these products u find in the us are named differently and are found much harder in my country i tried to find a different way!! that mosquito dunks thing sounds good but i have no idea where to find it or how to ask for it in my language but il try and look around explaining what it is maybe someone will be able to direct me from there!! would you mind checking my journal as i have posted another way i was thinking of getting rid of those damn gnats on which you could comment advise?? i would really appreciate it bro thanks heaps for the help!!!!

Are they spider mites, or real gnats?

they are tiny flies that live in the soil but they can fly they have black/grey bodies and i see them crawling on the soil as if they live in it!! im not an expert to know for sure if they are gnats but from what i read they fit the description in comparison to all other insects i have read about but still wouldnt know exactly!! il try and take a picture of one of those bastards when i get home!! is there any special characteristics i should look for to see if they are gnats?? are there other type of flies that live in the same way but are not gnats?? also if you check my log i give a more detailed description of how it happened if it would help understanding thanks for the help sir!!

ow and they are not spider mites they are tiny flies as i said!!!