Originally Posted by Blossom

A good question if your lawn gets a lot of shade. I have the same problem. Indeed, you have to let them dry out some before you can sweep 'em successfully. Tricky in high-dew days of autumn.

The RHS "Encyclopedia Of Gardnening" says

* The casts NEED to be removed since they provide a site for airborne weed-seeds to germinate in.
* "Disperse by brushing. If numerous, apply carbaryl when the soil is warm & damp"

You rest your case.