Q. I have a major problem with houseflies. I have tried chemical sprays and foggers, but I have to lock up my three cats to use them, the sprays make me feel a little ill, and they don't even seem to work that well. I did a little online research and found that flies apparently don't like herbs, so I made little sachets of dried herbs and I'm growing fresh basil, chives, and sage; but the effect is not dramatic. Do you have any other suggestions?
- --Anne in Philadelphia, PA
A. Those sprays and foggers are a much bigger danger to YOU and those cats than they are to indoor insects—especially houseflies, which have become resistant to just about every known chemical. I always preach against the use of such toxins outdoors because of their dangers. Well, those dangers are increased exponentially when you (and again, your pets) are trapped inside with those nerve toxins and hormone disruptors. (I wouldn't expect the herbs to be much help either; but at least they won't hurt you.)
First, check all your screens and make any necessary repairs and replacements. Then try and make sure that flies don't have access to the kitty litter area. Never leave any uneaten cat food out in the open, and make sure your trash and garbage is well sealed; you don't want to provide food or breeding sites for your unwanted houseguests.
Then turn to what may be THE oldest manufactured organic pest control product available. Good old non-toxic flypaper will capture pretty much every fly in the house overnight. First made in Grand Rapids, Michigan back in 1887 ("Catches germs as well as flies" was an early slogan), flypaper remains unsurpassed at solving indoor fly problems over a century later.
Flies are attracted to light and like to land on vertical surfaces, so carefully pull the length of sticky paper all the way out of its tube, hang it about a foot away from a lamp or other light source in a fly-filled room, turn off all the other lights and then close the door. In the morning, all the flies in that room will be stuck tight to the paper. Take it down using a big sheet of newspaper (so you don't get stuck to it!) and throw it away. Or use one of the more modern designs that captures flies with sticky stuff "invisibly" using a concealed trap and lure.
Q. My husband and I did a lot of work last spring to build a raised-bed garden; we even made a small pond. It looks great, but there are tons of houseflies out there. They seem to 'roost' at night on a little willow bush we planted in the back corner! Spraying is out of the question; although some days I am tempted. Is there some natural way to get rid of them, or at least knock down their numbers significantly? Could they be attracted to the large amounts of compost we put on our raised beds?
- ---Barb, in the Port Richmond section of Philadelphia
They're not there for the compost. Houseflies are attracted to manure, rotting meat and the like. So make sure your trash and garbage cans are well sealed and clean up after your dog if you have one. Some flies are also attracted to the flowers of certain plants, which they alone pollinate; so do a little research and see if you have something growing that requires their assistance to bloom.
There are also several beneficial insects that LOOK like houseflies, but are not. The most important is the tachinid fly. This fierce foe of garden bad guys lays its eggs on or near pest caterpillars, Japanese beetles, squash bugs and stink bugs. The pest eats the eggs or the baby tachinid fly burrows into it; either way, the pest dies and more tachinid flies emerge. You could well find these awesome beneficials in large numbers in a healthy garden like yours. Take a good look at a couple of your supposed houseflies. If they have big, bristly hairs on their abdomen, they are tachinids and should be protected (and bragged about to fellow organic gardeners).
If it turns out that they are just houseflies, purchase some outdoor fly control traps (see next question) and grow some Nicandra plants this season. That's N-I-C-A-N-D-R-A. Also known as the "Shoo Fly Plant" and "Apple of Peru", this distant relative of the tomato produces beautiful blue morning glory-like flowers and natural compounds that act as a form of fly birth-control, sterilizing houseflies (and whiteflies) that land on the foliage. Again, that's Nicandra; the J. L. Hudson catalog carries the seeds.
Q. What can farmers do to get rid of flies? Manure happens, you know. And even when it's disposed of, the flies congregate around the barns and feed lots. There are animals, kids and ponds on this farm, so we want to remain organic. What do you suggest?
- ---Mary Ann; Mary Ann's Michigan Trees and Shrubs in Paw Paw, MI
A. Common sense pest control expert Bill Quarles, head of the BIRC (the Bio-Integral Resource Center) in Berkeley, California, devoted a recent issue of his organization's excellent journal, "The IPM Practitioner" to a really cool method of organic fly control—commercially available fly parasites. These are highly specialized wasps; so tiny we can barely see them, but large in the eyes of terrified flies. You buy them mail order, release them in the fly-ridden area, and the wasps lay their eggs inside the 'larval' forms of the flies—those miserable maggots. A baby wasp soon consumes its host, negating that potential fly, and then breeds to continue the cycle.
It's very effective in your type of situation, says Bill, who adds that you might also want to try a couple of different commercial flytraps as well. These are fairly simple devices—either a pheromone or food lure gets the flies to go inside, where they are trapped on a disposable sticky paper surface. Hey, we're back to flypaper again! Except that this sticky stuff is safely inside a trap, where it won't accidentally catch birds or beneficials.