How do anti mosquito items work once they are at maximum level?

Yo tengo 5 lámparas antimosquitos al máximo y no me sale nunca que sea un pedido, o que como con otras combinaciones, cuando tienes 3 iguales se produzca un pedido... No sé si seguir acumulando o darme por vencida y venderlo....

I never found a use for them, eventually just sold them to clear space. I asked on a couple of sites and no one had a better answer.

If you have two mosquitoes you have can have more money.