It's been about 10 years since I used those JB traps and when I took them down I'd save the attractant part in a sealed jar, they still worked well the next season too. It may depend upon the manufacturer for the potency?

If you have something like a bag-a-bug and it's rained, the smell of rotting beetle carcasses might be deterring the next batch. Most traps come with spare bags. Equally, the attractant is an odor and high heat might cause it to evaporate faster or rain cause it to wash away.

Sigrid I think you are right, it did smell BAD so I emptied it. That explains why they came close but flew off