Why might untrained observers mistake aggregations of ashy mining bees for a social gathering?

Answer

Favorable local conditions cause them to excavate tunnels nearby

Although they are solitary, they may be seen in close proximity because many females independently choose to nest near each other if the local soil conditions—well-drained, dry, and sunny—are ideal for burrowing.

Why might untrained observers mistake aggregations of ashy mining bees for a social gathering?
faunainsectbeeaggressiveness