I am talking about flies. Fat black flies that emerge from moist chicken poop. The first year we had chickens, they ranged freely throughout our yard. Their freely dropped pooplets bred flies. Flies are annoying. And in sufficient numbers, flies draw wasps.
Wasps prey on flies, but they’re not that good at it. When I was writing my dissertation on the ecology of predator-prey systems, I would sit outside and watch the flies buzz around a poophill. I am not sure I ever saw a wasp capture a fly, but the Ecology of Fear was evident.
Briefly, a predator has a certain impact on the abundance of its prey population by killing individual prey, but its larger impact is through behavioural control. Fear of the predator alters the behaviour of the prey. Increased vigilance and shifts in the use of space by the prey reduce their chance of being captured and killed, but also reduces fertility. And this impact is much greater than the relatively few individuals actually captured by the predators.
In the case of the flies, the furious buzzing about the poophill was severely affected by the presence of the wasp hovering on the outskirts and making fumbling attempts to capture the flies that landed on the poophill. A fly is hard to catch mid-air (dynamic 3D), but a much easier target once it lands (static 2D). And in order to make use of the poophill that so attracts them, flies much land. You see how this works.
Alas, although a fascinating example of the ecology of fear, the wasps, and the poophills they frequented, were unwelcome at our outdoor BBQs. The chickens were confined to their run where there was a better chance they would turn over their little poophills whilst scratching in the dirt.
We tried fly tape, but took it down when we found dead songbirds stuck to it (sad). I took to dusting moist poophills with diatomaceous earth when the weather was nice. This doesn’t prevent flies from frequenting poophills, but might prevent larvae from emerging.
Finally, I found some organic fly traps that actually work. The RESCUE fly trap is very simple. This toxicologist is always suspicious of insect-killing devices, but the active ingredient in the Rescue trap is ‘Putrescent egg yolk solids’ – how appropriate.
These traps are disposable. Once filled with flies (eeeewwwww), you shut the trap door and send it to the landfill. Very convenient, but not very ‘sustainable’ of me. I have my eye on the Rescue reusable fly trap where you just purchase the egg solid powder and add water. Of course, we could start putrefying our own egg solids. There, now I have offically grossed out every last one of you… 😉
Finally, a video of the trap in action that will fascinate and/or utterly repulse you!