Without a picture, just guessing. Could be black aphids, which have wings as adults. Ladybugs will eat them for lunch. Neem should not hurt the ladybug adults but can have negative effect of formation of ladybug larvae. Squishing is best while population is low. I have found the more I spray to kill the harmful insect the more beneficials I affect and then my whole garden is out of balance. If you must spray... a soapy solution on the underside of leaves will take care of aphids if done often during infestation. You can make the solution yourself or buy the Safer product.

Thank you for this - I did find a picture of black aphids that looked like my visitors, and I did a soap, oil and water spray of the underside and stems of all of my tomatoes (and most everything else, while I was at it - I'm not sure what else they will attack)

Hopefully, that will knock them back, and now that I know what to look for, I'll be squashing with vengeance.

Keep your eyes on your eggplants too, queuetue. Last year my eggplants seemed to attract them more so than anything else in the garden...including roses.

There's a photo in the bottom right of the cabbage aphid with wings.

Here is a link that might be useful: Sucking Insects

The wings were a stubbier, and the entire insect was black (the behind looks a little lighter here) but yes, that looks like my marauder.