Lately there have been a few houseflies buzzing around and bugging me (bad pun of course intended). At lunch 2 big ones were beating against the screen in the kitchen window. So I closed the window and trapped them.
They have no food and if it doesn’t rain will have no access to water. How long will they live?
I understand that houseflies have a lifespan of 2-4 days, but I assume that’s under circumstances where they can eat and drink.
Well, for organisms capable of experiencing pain and suffering it is. Are insects capable of feeling negative sensations that we humans associate with hunger and thirst?
I’m pretty confident that insects are incapable of attaining conscious awareness of being deprived of food and water, understanding the likelihood of impending debility and death as a result, or experiencing emotional stress caused by such realizations.
Well, yeah, it is easy for me to say that houseflies don’t have conscious awareness or rational understanding of food deprivation and imminent death, or emotional stress caused by such awareness, because it’s scientific fact.
Suit yourself, but your personal choice tells us nothing about whether a housefly actually experiences suffering when starving to death. As you yourself noted, anthropomorphizing the experiences of non-human animals based on how humans would feel in similar situations is not a reliable guide.
Assuming the screen is accessible from outside the house without an intervening pane of glass which you can’t open, you could zap the flies with a spray of strong detergent solution, which isn’t a “poison” as far as humans are concerned (unless they’re immersed in it or something similar).
Of course, Death By Soap is not pleasant and your conscience would have to deal with the brief but poignant demise of the flies.
I speak as someone who dislikes accidentally trapping moths between the storm door and inner door when they fly in as I enter or exit at night, and takes pains to release them.