Aquatic and terrestrial ecosystems are connected by resource subsidies, often in the form of emergent aquatic insects that enter terrestrial environments after metamorphosis. Emergence frequently occurs in discrete pulses, periods when large numbers of individuals move from freshwaters into terrestrial environments and become food for consumers. This resource transfer is impacted by anthropogenic factors, including the pollutant artificial light at night (ALAN). The widespread adoption of LED technology has increased shoreline lighting and shifted the spectral composition of ALAN towards peaks in short wavelengths. A unique characteristic of LEDs is their tunability to emit specific wavelengths, creating an opportunity to minimize impacts, but how different LED wavelengths influence emergent insects across taxa and periods of high and low emergence remains understudied. To determine whether the effects of quasi-monochromatic LEDs on emergent flux varied through time, we installed replicate treatments of four spectral compositions (violet [410 nm], green [530 nm], red [630 nm], broad-spectrum white [4000K]) and a dark control in littoral and riparian zones of a Michigan (USA) lake. We collected insects on seven nights (June through September) using pan traps, encompassing periods of both high and low emergence. We evaluated differences in insect abundance, biomass, individual body size, and diversity among light treatments, habitats, and dates using three-way repeated-measures ANOVAs. We calculated differences in the effect size of wavelength and habitat on date over time, and community composition using non-metric multidimensional scaling (NMDS) and adonis permutation procedures. Insect abundance and biomass were greatest in violet treatments, though the magnitude of this effect strongly depended on sampling date, ranging from 352–5133% greater abundance and 389–6824% greater biomass relative to dark controls. Individual insect size was also greater under violet light but varied by date. These patterns were driven by taxa-specific responses, with emergent aquatic insects being more strongly attracted to short-wavelength light than insects of terrestrial origin, particularly during peak emergence of large-bodied caddisflies. Overall, our results demonstrate that ALAN alters aquatic–terrestrial fluxes, but effects depend on wavelength and sampling date, highlighting the dynamic nature of these impacts.