Yep -- more than just swish -- I start by washing outside in a bucket with water from the faucet swirling in along the side so the water is spinning and overflowing -- aphids that float up will be spilled out. I do this three times (saving the water for later use -- caterpillars (and hopefully those clear ones you got there) will sink to the bottom so I pour out the water -- to water with or in a large reservoir bucket/tub, then save the caterpillar water and give them to the goldfish. (I used to dump in the fish pond)
Once in the kitchen, I trim the heads from the stalks and soak in a deep bowl or pot with salt water and a towel or plate on top to completely submerge. If more than comfortable number of bugs still come out, then I do a second soak and this time use a squeeze of lemon juice or apple cider vinegar.
I do all these because I prefer to steam my broccoli and anything in the heads will stay in there. If I boiled the heads, then they will come out in the water. For soup-making, you might blanch them in boiling water first if you want to be sure... But if you are puréeing, well, you won't see them to gross you out at least.
Be sure to cook them soon-ish and not keep them in the fridge for long -- any bugs will continue to feed in there and the yellowing buds will spoil faster, which becomes a nightmare to clean.
