The accompanying photo shows a snake, approx. 18" long, which appeared near my yard. I'm assuming it's a non-poisonous snake, but elected to leave it along to do reptilian things. Can you identify it and say whether it's a useful in gardens in keeping insects, etc., at bay? Thanks for whatever information you can provide.
This is a juvenile black rat snake. The juvenile black rat snake is not black. They are very light gray with dark brown almost black rectangular blotches on the back. This snake is harmless and not poisonous.
Snakes in general are beneficial because they help keep the rodent population down. See our publication on snakes for more information http://extension.umd.edu/hgic/snakes