Don't just speculate! http://nature.com/articles/doi:10.1038/nature21709 http://nature.com/articles/doi:10.1038/nature21709 It had a measurable impact when pl

Don't just speculate! http://nature.com/articles/doi:10.1038/nature21709 http://nature.com/articles/doi:10.1038/nature21709 It had a measurable impact when planting "wild"flowers on 2% of the land alongside English fields, with a little more searching there's probably a study on gardens. (From the paper: "Here we show that the survival of family lineages from the summer worker to the spring queen stage in the following year increases significantly with the proportion of high-value foraging habitat, including spring floral resources, within 250–1,000 m of the natal colony.") However, the jury's out on "insect hotels": http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0122126 http://journals.plos.org/plosone/article?id=10.1371/journal....