Hola gabo! I dont know anything about marihuana, and I dont like drugs of any kind, they are dangerous if misused... but you can keep the bugs away using Neem, Tobaco and Noni (dont know the name of the plant on english). Be carefull with the Noni and the neem, they are kind of agressive.
Depending on the bugs you want to keep away, you can even use the "borra del café".
I hope that its legal to have marihuana in the country you live, so you dont get in troubles.
RE: Growing marijuana at home