Are you familiar with the concept of flux? It is sort of a technical concept, and it usually relates to the rate of something (heat, a chemical reaction, photons) across a unit area. That rate can be in the process of changing.
There is a website called the “Simple English” wikipedia, designed to explain difficult concepts to those of us who have a hard time understanding them. It defines the concept of flux as “How much stuff goes thorough your thing”, and uses the idea of air going through a butterfly net–the flow of air being the flux.
So can we talk about a butterfly flux? Imagine an alfalfa field. The air above it is filled with butterflies. The butterfly flux would be that population of butterflies that more or less continuously use that field to obtain nectar and to lay their eggs. A prairie area or a wooded area would have a butterfly flux.
The flux would have to be the number of butterflies that are more or less supported by the habitat, not just those that are attracted to nectar or to a bait.
The flux changes over time. It could be expressed as a number–the number of butterfly observations per unit area during a Pollard transect, for example. It would be difficult to pin down, though–that number constantly changes throughout the year and from year to year.
But the butterfly flux over a cultivated corn field or a parking lot would be different than that over a mature wetland or a prairie.
The way we modify habitats has a significant effect on the butterfly flux.