  Only 20\% of old field stars have detectable debris discs, leaving open the
question of what disc, if any, is present around the remaining 80\%. Young
moving groups allow to probe this population, since discs are expected to have
been brighter early on. This paper considers the population of F~stars in the
23~Myr-old BPMG where we find that 9/12 targets possess discs. We also analyse
archival ALMA data to derive radii for 4 of the discs, presenting the first
image of the 63au radius disc of HD~164249. Comparing the BPMG results to disc
samples from $\sim45$~Myr and $\sim150$~Myr-old moving~groups, and to discs
found around field stars, we find the disc incidence rate in young
moving~groups is comparable to that of the BPMG and significantly higher than
that of field~stars. The BPMG discs tend to be smaller than those around
field~stars. However, this difference is not statistically significant due to
the small number of targets. Yet, by analysing the fractional luminosity vs
disc radius parameter space we find that the fractional luminosities in the
populations considered drop by two orders of magnitude within the first
100~Myr. This is much faster than expected by collisional evolution, implying a
decay equivalent to $1/\text{age}^2$. We attribute this depletion to embedded
planets which would be around 170~$M_\text{earth}$ to cause a depletion on the
appropriate timescale. However, we cannot rule out that different birth
environments of nearby young clusters result in brighter debris discs than the
progenitors of field~stars which likely formed in a more dense environment.
