Bats rock

[caddis]

Bats not only eat insects that are a nuisance to humans (a small brown bat can devour up to 600 mosquitoes in an hour), but can provide significant agricultural pest control services. In one season, a typical colony of about 150 big brown bats in the Midwest eats 50,000 leafhoppers, 38,000 cucumber beetles, 16,000 June bugs, and 19,000 stink bugs (11)—not to mention thousands of moths such as adult cornborers, earworms, and cutworms.
Bat Housing




http://www.attra.org/attra-pub/farmscape.html#Long2

[c-ray]

I had a friend turn me on to this a few years ago, he was planning to build a very large bathouse to collect his own guano

I believe the general rule of thumb is that bats that eat bugs make a higher in nitrogen guano while bats that dine on fruit make a higher in phosphorus guano...I think I read that the bats in the usa and canada are exclusively insect eaters

here's some bathouse plans:
http://www.batcon.org/home/index.asp?idPage=47
http://mdc.mo.gov/nathis/woodwork/ww15/
http://www.wildaboutgardening.org/en/features/section1/bathouse/bathouse.htm

and here's a cool bat page
http://www.batbox.org/