We changed out the oil in our hive vermin trap pans today. We had planned to do this coincident with the last Autumn powdered sugar shake we did yesterday. As usual, I went through the contents of the pans pretty thoroughly just to keep track of what’s falling out of the hives into the traps. Unfortunately, I was unable to isolate the oil samples from each other, so I’m not entirely sure what came out of which trap. But I’m pretty sure all the wax moth larvae came out of the pan under the entrance end of Hive 1 (brood area). The oil in that pan was also red in color, which was somewhat surprising.
In all, I counted about 60 full-grown wax moth larvae, and one wax moth pupa. The picture doesn’t give a good idea of the size. They were mostly about an inch to an inch and a half. Some of them were a little smaller. What was really surprising though was they were almost all alive and apparently thriving in the oil that was supposed to drown them. I gathered them up into an old yogurt cup with a lid, and sent the first few on a tropical vacation in the microwave. That stunk up the place like vine vinegar though, so even though the sound of them exploding in the yogurt cup was quite satisfying, the remainder went on a winter trip in the freezer.
I don’t know if the wine vinegar smell came from the wax moth larvae or from the fermentation of all the powdered sugar mixed in with the oil from the sugar shakes we have done over the last three weeks. As you can see from the picture, there were also a good number of Varroa mites in the pans, along with some other vermin. I counted about 10 SHB larvae (all dead), and sadly a fair number of dead honeybees (about 20 or so). I didn’t do a thorough count on anything but the wax moth larvae, though. There were also some adult flying insects (flies, and other types of bees), and a good number of ants. The vast majority of the trap victims, though, were gnats. There must have been tens of thousands of them.
So the good news is that the oil traps are working. We have seen no evidence of any pests except Varroa mites and ants on any of our frames. But the bad news is that the vegetable oil we’ve been using isn’t killing the wax moth larvae as expected. Therefore, we will switch to mineral oil on the next go ’round. In the meantime, I need some ideas for something lethal (not to honeybees), that is oil soluble and non-volatile to mix with the vegetable oil.