When you set out a crystal bowl, and place a fresh gardenia bloom in it with a silent thank you to the angels, they know you are showing respect. Or, when you light candles and incense before beginning your meditation, and you offer a welcome prayer to the angels, that too is a sign of respect. But when a fly or moth flits around your altar table and you grab a swatter to put an end to it because it annoys you, it shows a wanton disregard for the life of those creatures.
Think of the world and everything in it as made by the Creator; each thing has its own holiness. Flies and moths are not sentient beings aware of their own consciousnesses like humans are. In other cultures, the reverence for life is so great that people strive to avoid hurting other living creatures. In India for example, Jain priests (Jain being an Indian religious sect) wear masks in case they might inadvertently inhale a gnat or other insect, thus ending its life.
Attuning your energy to the life force of other creatures fosters an understanding of the spark of divinity in all. Small, albeit sometimes annoying, creatures like flies and moths may seem useless, but in fact they have their place in the grand scheme of the divine. When you feel and demonstrate a loving respect for other life forms, your energy vibration becomes more attuned to the angels.