With the warm summer weather, mosquitoes are returning to our neighborhoods, taking some of the fun out of summer evenings and time spent outdoors. Horticulturalist and local gardening guru Charles Cresson spoke to aFewSteps about how to control mosquitoes without resorting to chemical insecticides.
According to Cresson, “Mosquitoes in this community are an unnecessary plague,” and the best way to combat that plague is by getting rid of standing water. Mosquitoes lay their eggs and the larvae mature in standing water – a process that typically takes 10 to 14 days, depending on temperature. Cresson encourages us all to think carefully about where water might be standing in our own gardens – in a stack of flower pots, for example, in a child’s toy that’s been left out in the rain, or in a clogged or sagging gutter that doesn’t drain properly. Some mosquitoes can breed in as little as a thimbleful of water – “that’s the crease in a plastic bag.”
For standing water you can’t get rid of (including bird baths and ornamental ponds), Cresson recommends Bacillus thuringiensis subspecies israelensis (Bti), a naturally occurring bacteria which kills mosquito larvae but is non-toxic to other organisms in the garden, including children and pets. Bti is available commercially in the form of “mosquito dunks” or “mosquito pellets” which float on the water surface. Swarthmore Hardware carries both dunks and pellets. The proprietor, Charlie Devaney, can answer questions about using Bti in your garden and reports success with simple mosquito traps using the dunks. A single application of mosquito dunks lasts about a month.
While effective against mosquito larvae, Bti has no effect on adult mosquitoes. Keeping gardens weeded and lawns mown helps to deprive adult mosquitoes of shelter. Larger insects, birds, bats, amphibians and some fish all eat mosquitoes, but there are no animals native to our region that rely exclusively or even predominantly on mosquitoes for their diet. Because mosquitoes are weak flyers, a fan operating where people are congregating may be the most effective way to keep them from bugging your party.
Both Cresson and Devaney point out that mosquitoes are a very local problem. According to control-mosquitoes.com, the species typically found in and around our homes and gardens have a limited flight range of about 300 feet. In our area, that’s about the size of 2 typical properties. As Charles Cresson puts it, “You don’t have to suffer in your backyard, but you might be at your neighbor’s mercy.”
Additional tips for homeowners are available on the following websites: