Well it's that time of year when the Alameda County agricultural department hangs interesting objects in our fruit trees to check for any bugs/pests that shouldn't be in the area, potentially threatening California agriculture.
In the past, cardboard pheremone traps were hung in the branches of the fig tree to check for Mediterranean flies and fruit flies. Two years ago one of these glass bottles was hanging in the fig tree. But we never ever spotted people from the agriculture department hanging up the traps or removing them.
This year, lo and behold, we discovered this bottle hanging in the lemon tree!
This time the Alameda County agricultural department didn't leave a note for us to inform us which critters they are looking for exactly. So imagine how excited I was to see one of the agriculture guys taking the bottle out of the tree and examining it. I ran outside and asked him what the trap is for. He said they were checking to see if Mexican fruit flies are in the county. And at the same time seeing if any bugs that shouldn't be in the area, are.
The traps are only hung in mature fruit trees that are producing fruit, because they will attract bugs. Because the figs in the fig tree won't be ripe for a month or so, the trap was put in the lemon tree instead, because the fruit is riper.
The liquid in the bottle is a concoction of water and yeast which attracts flies of all sorts. The agriculture guy told me that he comes by once a week to pour out the liquid through a filter to then check what kind of flies were attracted. And it's important to check weekly to ensure that the water didn't dry up.