Sunday, May 12, 2013

those idyllic hours between cluster fly hell and tickie time

The cluster fly myths listed below have been seen on the Internet at one time or another. Please feel free to do your own research.

Millions of cluster flies were killed in preparation for this post.

It little bothers me that there is snow on the ground this fine Mother’s Day morning. Yes, snow. Kind of a sloppy snow with green grass and daffodils poking through—the kind of snow one might expect in May in the Upper Peninsula—and it may snow more today, or rain, or do this or that, it little matters to me because these are the idyllic hours between cluster fly hell and tickie time.

Yes, the cluster flies have vanished, poof, gone shortly after the first of May, and I am pretty sure as long as it snows now and then the ticks will hang back.

Let it snow.

Through the kitchen window about 9:30 last night.
This is the first time since August there have been no cluster flies in or around the cabin. Eight, nearly nine long months. Wasp activity also picked up in August and September, and before that, of course, mosquitoes. And before the mosquitoes, ticks.

Let’s back up.

Everyone knows about mosquitoes and wasps and ticks. Not everyone knows about cluster flies. There may be a reason for this. It seems people don’t like to talk about cluster flies. I have been told that “everyone has them” (around these parts) and that “there’s no getting rid of them” (around these parts), and yet, nobody talks about them. (On the other hand, there is much discussion about mosquitoes and ticks.) In the fall, when the cluster flies were coming inside to hunker down for the winter (see Myth #2 below) I would say, conversationally: “Jeepers, are the cluster flies really bad this year or what?” The reply? A blank stare. Then, “Cluster flies?” as if I were talking about something unheard of in these parts. “Yes,” I would say, wondering if I should persist. “All those flies that gather on the windows … ?” “Oh … ” a pause. “You mean those flies … ” And then, after a bit more coaxing, “Oh yeah, they’re awful, I just vacuum them up.” (To be fair, one person has readily talked with me about cluster flies. He is the only person I know to have gotten rid of them. He used an insecticide available on the Internet—not that contraption filled with crushed eggshells. Though that may work.)

Cluster flies look pretty much like any other fly, but they have specific behavior that is, indeed, odd, and it is riddled with myth and nonsense. In these parts, they appear suddenly in late August and by September hordes of them are in the house, clustering on windows.

Myth #1 Cluster flies congregate on sunny southern windows.
Truth Cluster flies congregate on any and all windows.

Cluster flies do not bother one’s person—they prefer windows—but as they mass inside they do fly from window to window and if you are in their way, bink. They also dart around just outside the cabin. Bink, bonk. Five, ten feet away, no flies. By October, there are so many flies in and around the cabin it is a nightmare. The only consolation is that when daylight fades, the flies disappear. But then, turn on a lamp …

Myth #2 Cluster flies come inside during the fall to find a snug, warm place to hibernate.
Truth Cluster flies are flying around and congregating on windows and light bulbs all winter long. This is hibernation?

Direct exposure to sun (or heat) does seem to liven up these flies—this becomes more evident during the winter months when the day starts with a cold house. As the house warms up, so do the flies. They are definitely more groggy during the winter (except maybe on a sunny day), and they are easily picked off with fingertips or a sweep of tissue. I catch a lot on fly paper that I hang strategically by a lamp. And they are incredibly easy to vacuum. In fact, I vacuumed so many last fall with my little shoulder vac that I had to change the bag every night. When that vac busted—I stepped on the cord once too many times and the cord frayed and pulled away from the machine—I nearly had a nervous breakdown. You see, I had started a war against these flies, and once a war is started and you see yourself losing, well, do you back down or do you fight on? Do you let it become an obsession?

I knew there were flies when I bought this place. I thought they would not bother me.


I replaced my vacuum with another bought used online and within a few days was back in business.

Myth #3 For every one cluster fly you see, there are 19 more.
Truth Really? Does this make sense? Think about it. For every one fly you see, there are 19 more. So I see a fly, there are 19 more, I kill a fly, are there still 19 more? Why 19? Why not 20 or 30 or 17? If you can’t see them, how do you know? And if you do see them ... there are 19 more.

Cluster flies crawl up windows, hang out at the top until they lose their balance or fall asleep or get bored. Then they fall to the window’s sill and, if it’s spring, spin on their backs. It is a death spin. In the fall and winter, they simply start crawling back up to the top of the window.

Myth #4 After hibernating (ha!) through the winter, cluster flies awaken in the spring and go outside to breed.
Truth The flies show no different behavior in the spring except for this death spin on the windowsill. Is it part of the mating ritual?

There are more flies in spring than in winter, inside and out, but I have no evidence as to which direction they are moving. In my experience, they are moving in both directions. If I leave the windows and doors open, some fly in, some fly out. The day the chickadee flew in led me to believe that leaving windows and doors open was not a good idea, no matter which way the flies were going.

(Note: Chickadees eat cluster flies. Thank you.)

Myths #5 & #6 Cluster flies breed outside in the spring, laying eggs in the ground (and earthworms are involved … ). A cluster fly’s life span is two or three weeks.
Truth Well, all I can say is, where the heck are all these flies coming from in November, December, January, February, March, and April? There’s two feet of snow on the ground! Shouldn’t these flies be hibernating? Or dead?

All of a sudden, right around the first of May, the cluster flies disappeared. For every one I saw and killed, there were no more. It is blessed to look out a window and not see a dark speck (or 19) skittering across it. It is blessed to have an empty bag in the little vacuum, and the little vacuum put away. Now, for these few short hours, there are no cluster flies, no ticks, no mosquitoes, no wasps. Okay, granted, the other day when it was sunny and 80 degrees there were wasps outside, lazing around, but the next day (40 degrees with rain) they were gone. They’ll be back. And any day now, the ticks will start, hitching a ride on cuffs and sleeves, coming in from the fields, dripping from trees, creeping and crawling and looking for skin … oh, don’t get me started. Just get out the tweezers. And leave me these few idyllic hours …

Through the kitchen window about 9 this morning.


  1. Oh how I sympathise! I returned from visiting my son in Bristol (UK) on Sunday evening after an unseasonally hot and sunny October day to find that my bedroom at the top of the old house where I live in Shropshire was all abuzz with thousands of the aforementioned cluster flies. It was like a scene out of a horror movie. Horrible! I am sorry to admit that I resorted to spraying the invaders and retreated to the spare room. I have had them in before, but never in such numbers. Just like you I went into battle and yesterday after work, after vacuuming up and disposing of the bodies, I cleaned the windows thoroughly then filled the thin gap between the stone frame and the sill with a silicone sealant. I then liberally sprinkled lavender essential oil along the stone sills as an extra deterrent. Yesterday evening there were several more dead bodies and only a lone survivor but it had been a cool cloudy day. Today it has been very warm and sunny again. What will I find on my return?......................................

    1. Aye! My sympathies. I have been doing a little experimentation this fall as cluster fly season picks up, and I hope to report soon on results. Perhaps I will try the lavender. Also have some hedge apples (I hope) coming in the mail ... have heard they might have powers ...