Here are the instructions. This still does not answer my question about using compost tea as the "liquid medium" for spraying the nematodes...nor does it address whether it's ok to add the nematodes to the water BEFORE beginning the brewing process. APPLICATION RECOMMENDATIONS: Application for the 10 Million nematodes: Mix with water and spray or sprinkle on the soil along garden, lawn or crop rows or around larger plants. Place the entire sponge of nematodes in a bucket. Pour at least two quarts of water over the sponge and repeatedly squeeze for a few minutes to get the nematodes out of the sponge and into the bucket of water. Discard the sponge and pour the water into a sprayer or water can. At this stage, you should have the amount of nematodes indicated on the bag suspended in about two quarts of water. Add clean water to dilute the suspension and make up the volume that your sprayer requires. You can always add more water for distribution of the nematodes to cover the required square footage. Just add 2, 5, or 10 gallons of water so that you have enough to allow even spread of the nematodes. Keep the soil moist during the first 10 days after application.

Though I've never used nematodes to try and get rid of thrips, I have used them to try and get rid of japanese beetles. What I discovered is fewer grubs in my garden but still as many on my plants. The problem with the beetles and thrips is they can fly. When I did research on how to get rid of thrips I found information on insects that eat them. One such insect that is easily recognizable is the pirate bug. We were infested with thrips, so much so that I found 30+ on EACH daylilly flower (not plant, flower) and we have hundreds! My new roses couldn't bloom at all, especially my Moonlight Magic, Stainless Steel, and Neptune. I had to clip all the buds as they were so damaged by thrips I was concerned about the health of the plants (ironic how I was more concerned about aphids before this). After reading about the thrip-eating bugs I decided to see if I could find any on the daylillies. I found one pirate bug and it was enough to convince me to wait and see for a few weeks. 5 days later and two of my roses have bloomed today. I inspected them for thrips and found 2-3... and a pirate bug. Pirate bugs are my roses new best friends and I, at last, can enjoy some blooms! They haven't yet finished up the population on the daylillies, but I haven't given them much time, either. If you decide not to get the nematodes you should consider predatory insects.

I used the nematodes from Home Depot and from Gardens Alive, even looked under the microscope to see them wriggling around. I've noticed no difference in the grub population since they were applied several years ago, but I did see a couple last season that looked sick (I.e yellow and thin)...unless they were just a different kind of grub.

There shouldn't be any issues of applying both. Milky spore takes years to build up in the soil (through infecting grubs which then become spore factories) ... and then nematodes look like they are a lot of $$$ for spot treatment areas. I applied milky spore 3 years back after having moles for two years. They haven't returned... but at the same time I had moles come and go from my front yard too without treatment. So who knows. What you could do is go for the milkyspore... applied in late summer into fall. And then just set traps through this whole year.