This is a screencap from an interactive map at The Cornell Lab's BirdCast website. The intensity of the colors reflects the intensity of the migration in terms of number of birds in the air (750,000,000 at just after midnight), and obviously the arrows show direction of movement. For comparison, here is the image from 10:30 this morning (one-tenth as many birds migrating, the others presumably having landed to feed or rest).
There is a pull-down that lets you view any day going back to 2018. Awesome.
Modern radar equipment is also capable of detecting airborne insects. I've seen reports that they are now learning to analyse the data by adding radar "signatures" of different types of insects in order to distinguish butterflies from locusts from mayflies etc. Amazing.