In one of my other blog video's I showed you my infestation of butterfly and caterpillars. It is a heavy infestation and will be a hard one to eradicate.


This Blog will cover how to make a cheap DIY pesticide doser that will reach every small nook and cranny of your grow room to really get on top of a heavy pest problem. I have used this many times in the past with great success after traditional spraying failed in my grow rooms, chicken pens and kennels. It could also be used with pure water for any humidifying , fog, misting needs.





What you will need:

[The Prices are estimates]


>24v Ultrasonic Mister [£2]

[You may want multiple units for large rooms/ large amounts of mist]




>24v Power supply

Any source of 24V DC, make sure it can supply enough current for your planned number of misters and Fan.

Misters have a female 5.5mm Power jack [common size for wall mounted power supplies]


>24v PC Fan £1

24v Fan


> A Container Of your Choice with removable LID [Wide and shallow is better]


>Fan Speed Controller [Optional] £2

The basic ones just work as a voltage divider, so you can make your own from a potentiometer if you like.



>5.5mm 12v splitter cable [Optional] £2



How to build it:

As Always this is just a set of instructions, follow them at your won risk.

>I'm not including a wiring diagram with this blog, everything operates at the same voltage and it is as simple as wiring all parts in parallel.

>Cut 4 holes in the top of the container you plan to use, two the size of the fan you selected and two smaller ones for the waterproof bungs on the mister wires.

>Mount the fan so it is blowing air into the container [stops the motor getting wet] and alter the mister lead length in the bungs to place them in the middle of the container away from your inlet and exhaust holes.

>Add a exhaust pipe if you want to direct the mist to somewhere else.


How To use:

As a general mister or humidifier to keep cool in summer or for a Halloween project, just add water power it on and let it do its thing, use the fan controller knob to control the amount of mist you want.


As a Pesticide doser:

>Best to do this over night so the plants are less stressed

>Close all windows, shut of exhaust fans [make it a closed system]

>Fill the tub with the water soluble pestacide of your choice [see link below for a home made nicotine based pestacide]

>Turn the mister on and leave the room imediatly, check it is not leaking into places with people/ pets

>Come back int he morning, re open the windows and the live bugs should be gone.

>Repeat every few days to kill the new larva before they get the chance to lay eggs.

>A few repetitions usually work, if there is no effect change the type of pesticide, your pest might have become immune to your choice of poison.


You want the room to be cleaned to be full of mist, add extra ultrasonic misters as you need them if your room is large, position it so you get the best distribution of mist/fog.

If you are using this in an aquaponics system make sure to use a pesticide that is fish safe!


Here is my preferred "natural" Pesticide of choice, I usually use this first and seek alternatives if it does not work:

How to make a nicotine insecticide | eHow UK


Good Luck staying Pest Free, this is just my preferred method for heavy infestations, there are many other ways to achieve the same goal.