虻蜂取らず/Can't catch the horsefly nor the bee

虻と蜂を一度に追いかけて、両方とも取り逃がしてしまうという意。両方のものを得ようとして、どちらも取り逃がすこと。欲張りすぎたために、かえってだめになることのたとえ。
Comes from the idea that if you chase after both a fly and a bee at one time, you .won't be able to catch either and they will both run away. If you try and get two things, you'll miss catching both. An example of being too greedy and hence all the better that it became bad.

「仕事と趣味を両立させようなんて、結局、虻蜂取らずに終わるぞ」

虻・あぶ・horsefly
取り逃がす・とりにがす・miss, lose, fail to catch x wo - 他動詞
欲張り・よくばり・to be greedy, or a greedy person
両立・りょうりつ・compatible