Monarch (Danaus plexippus)

Species description
© - Eddie John

The Monarch, our largest butterfly, is a rare and sporadic migrant to Britain and Ireland. The majority of sightings are in the south-west of Britain. Although the butterfly now breeds in the Canary Isles and in a very restricted area in Spain, these migrants almost certainly originate from North America, as their arrival to our shores usually corresponds with major migrations there coinciding with favourable weather conditions that bring them across the Atlantic. (For further details on this species see

Rare migrant
LCI summary

Log Collated

This chart shows the index of abundance (LCI = Log Collated Index) over time. It shows fluctuations in populations from year to year, and is scaled so that the average index over the whole series is equal to 2 (horizontal line). Further details on the analysis of UKBMS data can be found [here]

This chart shows the average number of butterflies seen on transects between April and October across all sites (fitted values from a Generalised Additive Model). The blue line gives average counts over the full BMS series (1976 to date) and the red line gives the average for the last year.

This map shows symbols for the mean abundance at transect sites, with the colour of the symbol reflecting the level of abundance. Means are over all years. Grey background squares are the occupied cells as shown by the Butterflies for the New Millenium over the previous ten year period.