I've heard of many more growers using ladybugs indoors because they are cheaper and easier to get, and you can keep quite a good number of them around. I've used them myself in the past, not in my grow, but at a commercial greenhouse where I used to work, and they were very effective. I get an infestation of ladybugs in mhy grow twice a year, don't know where they come from, but I consider it good fortune and they really knock down the pest population!