Bats rock

[caddis]

[QUOTE]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)

[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/