Butterfly Conservation
Hertfordshire & Middlesex Branch
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Millhopper's Reserve

First and Last Sightings in Hertfordshire and Middlesex

Here are the earliest and latest sightings of our resident and migrant butterflies

For information at a national level. . . .

Butterfly Conservation First Sightings 2020

35 species of butterfly occur most years in Hertfordshire and 30 in Middlesex, together with the occasional migrant or vagrant. The following table lists the first and last sightings in the two counties. Dates highlighted in green signify the earliest during the period and those highlighted in orange signify the latest

Species Date 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021
Dingy Skipper
Erynnis tages
First 6-May 6-May 6-May 6-May 5-May 5-May 16-May 21-Apr 26-Apr 10-May
Last 20-Jun 8-Jul 8-Jul 8-Jul 15-Jun 17-Jun 5-Aug 4-Aug 20-May
Grizzled Skipper
Pyrgus malvae
First 4-Apr 25-Apr 15-Apr 21-Apr 12-Apr 12-Apr 1-May 21-Apr 16-Apr 23-Apr
Last 28-Jun 6-Jul 14-Jun 8-Jun 7-Jun 1-Jun 8-Jun 3-Jun 31-May
Essex Skipper
Thymelicus lineola
First 7-Jul 6-Jul 11-Jun 28-Jun 19-Jun 17-Jun 11-Jun 17-Jun 11-Jun 4-Jul
Last 28-Aug 31-Aug 10-Aug 27-Aug 13-Aug 26-Aug 4-Aug 21-Aug 8-Aug
Small Skipper
Thymelicus sylvestris
First 27-Jun 25-Jun 8-Jun 15-Jun 19-Jun 10-Jun 6-Jun 3-Jun 8-Jun 16-Jun
Last 2-Sep 20-Aug 7-Aug 22-Aug 17-Aug 30-Jul 11-Aug 21-Aug 1-Aug
Large Skipper
Ochiodes sylvanus
First 6-Jun 6-Jun 14-May 26-May 25-May 27-May 27-May 20-May 17-May 31-May
Last 31-Aug 5-Sep 14-Aug 14-Aug 13-Aug 13-Aug 5-Aug 28-Aug 8-Aug
Anthocharis cardamines
First 14-Mar 21-Apr 21-Mar 4-Apr 5-Apr 25-Mar 13-Apr 23-Mar 25-Mar 22-Mar
Last 20-Jun 2-Aug 13-Jun 28-Aug 22-Jun 10-Jun 7-Jul 20-Jun 9-Jun
Large White
Pieris brassicae
First 27-Mar 10-Apr 2-Apr 6-Apr 4-Apr 3-Apr 17-Apr 21-Mar 10-Jan 17-Apr
Last 10-Oct 7-Oct 31-Oct 11-Oct 6-Oct 3-Nov 13-Oct 22-Oct 1-Oct
Small White
Pieris rapae
First 18-Feb 29-Mar 6-Mar 23-Mar 22-Mar 15-Mar 26-Mar 25-Feb 22-Mar 21-Mar
Last 10-Nov 26-Oct 25-Oct 26-Oct 28-Oct 3-Nov 29-Oct 18-Oct 14-Oct
Green-veined White
Pieris napi
First 15-Mar 10-Apr 16-Mar 2-Apr 2-Apr 30-Mar 17-Mar 23-Mar 4-Apr 29-Mar
Last 14-Oct 30-Sep 28-Oct 12-Oct 2-Oct 6-Oct 5-Nov 4-Oct 23-Oct
Clouded Yellow
Colias croceus
First 4-Sep 21-Jun 8-Jun 9-Jun 26-Jun 7-May 18-Apr 29-Jul 12-Jul 17-Jul
Last 4-Sep 30-Oct 1-Nov 22-Sep 4-Oct 10-Nov 2-Nov 23-Sep 1-Oct
Gonepteryx rhamni
First 8-Feb 19-Feb 22-Feb 15-Jan 4-Feb 4-Jan 10-Jan 2-Feb 1-Feb 20-Feb
Last 28-Oct 29-Oct 31-Oct 29-Dec 14-Dec 16-Nov 14-Nov 30-Dec 1-Dec
Speckled Wood
Pararge aegeria
First 18-Feb 15-Apr 29-Mar 10-Mar 4-Jan 15-Mar 25-Jan 24-Mar 4-Apr 30-Mar
Last 31-Oct 30-Oct 31-Oct 29-Dec 31-Oct 10-Nov 31-Oct 27-Oct 22-Oct
Small Heath
Coenonympha pamphilus
First 11-May 5-May 4-May 10-May 6-May 22-Apr 9-May 15-Apr 15-Apr 11-May
Last 27-Sep 2-Oct 3-Oct 11-Oct 23-Sep 26-Sep 13-Oct 28-Sep 7-Oct
Aphantopus hyperantus
First 19-Jun 26-Jun 8-Jun 17-Jun 16-Jun 7-Jun 6-Jun 14-Jun 9-Jun 23-Jun
Last 6-Sep 5-Sep 27-Aug 22-Aug 18-Aug 27-Aug 11-Aug 31-Aug 10-Aug
Meadow Brown
Maniola jurtina
First 10-Jun 14-Jun 1-Jun 4-Jun 5-Jun 27-May 27-May 30-May 25-May 7-Jun
Last 29-Sep 15-Oct 28-Sep 2-Oct 21-Sep 16-Oct 29-Sep 27-Sep 6-Sep
Pyronia tithonus
First 23-Jun 29-Jun 18-Jun 25-Jun 1-Jul 6-Jun 21-Jun 25-Jun 13-Jun 5-Jul
Last 15-Sep 18-Sep 2-Sep 8-Sep 15-Sep 11-Sep 14-Sep 8-Sep 20-Aug
Marbled White
Melanargia galathea
First 18-Jun 26-Jun 11-Jun 15-Jun 5-Jun 9-Jun 1-Jun 14-Jun 8-Jun 15-Jun
Last 19-Aug 21-Aug 12-Sep 15-Aug 17-Aug 10-Aug 4-Aug 26-Aug 10-Aug
Silver-washed Fritillary
Argynnis paphia
First 1-Jul 7-Jul 17-Jun 29-Jun 1-Jul 7-Jun 10-Jun 16-Jun 2-Jun 23-Jun
Last 9-Sep 2-Sep 2-Sep 19-Sep 30-Aug 1-Sep 22-Aug 26-Sep 10-Aug
Dark Green Fritillary
Argynnis aglaja
First 25-Jun 24-Jun 11-Jun 15-Jun 19-Jun 13-Jun 16-Jun 16-Jun 30-May 15-Jun
Last 12-Aug 7-Aug 4-Aug 22-Aug 29-Aug 13-Aug 1-Aug 12-Aug 3-Aug
White Admiral
Limentitis camilla
First 28-Jun 5-Jul 13-Jun 27-Jun 29-Jun 14-Jun 13-Jun 23-Jun 9-Jun 27-Jun
Last 14-Aug 11-Aug 9-Aug 3-Aug 6-Aug 25-Jul 21-Jul 1-Aug 20-Jul
Purple Emperor
Apatura iris
First 4-Jul 9-Jul 21-Jun 30-Jun 4-Jul 18-Jun 19-Jun 22-Jun 20-Jun 4-Jul
Last 23-Aug 14-Aug 27-Jul 9-Aug 12-Aug 17-Jul 28-Jul 11-Aug 28-Jul
Red Admiral
Vanessa atalanta
First 2-Jan 1-Jan 2-Jan 9-Jan 7-Feb 2-Jan 2-Jan 18-Jan 9-Jan 26-Feb
Last 3-Dec 16-Nov 20-Dec 28-Dec 22-Dec 31-Dec 3-Dec 7-Dec 22-Oct
Painted Lady
Vanessa cardui
First 9-May 1-Jun 1-May 10-Apr 20-Apr 3-Apr 3-Apr 23-Feb 14-Apr 27-Apr
Last 2-Oct 9-Oct 10-Nov 23-Sep 14-Oct 22-Sep 22-Sep 22-Oct 14-Sep
Aglais io
First 24-Feb 3-Jan 3-Jan 14-Jan 21-Mar 17-Feb 27-Jan 8-Jan 3-Jan 21-Jan
Last 21-Dec 12-Dec 23-Dec 12-Nov 12-Nov 22-Nov 4-Nov 13-Nov 17-Dec
Small Tortoiseshell
Aglais urticae
First 9-Jan 19-Feb 13-Feb 8-Feb 30-Jan 5-Jan 12-Jan 14-Feb 9-Jan 24-Feb
Last 16-Dec 19-Nov 31-Oct 28-Dec 30-Sep 6-Nov 13-Nov 23-Dec 7-Nov
Camberwell Beauty
Nymphalis antiopa
First 11-Aug 9-Mar 30-May
Last 11-Aug 24-Mar 30-May
Polygonia c-album
12-Mar 26-Feb 5-Mar 24-Feb 7-Mar 2-Jan 4-Jan 11-Mar 28-Jan 7-Jan 21-Feb
Last 3-Dec 15-Nov 16-Oct 12-Nov 29-Nov 9-Dec 2-Dec 27-Oct 17-Sep
Small Copper
Lycaena phlaeas
First 30-Apr 16-May 13-Apr 27-Apr 29-Apr 6-Apr 26-Apr 20-Apr 22-Apr 20-Apr
Last 30-Oct 10-Nov 31-Oct 26-Oct 18-Oct 13-Nov 17-Nov 28-Oct 22-Oct
Brown Hairstreak
Thecula betulae
First 19-Jul 28-Jul 18-Jul
Last 6-Sep 19-Sep 11-Sep
Purple Hairstreak
Favonius quercus
First 4-Jul 4-Jul 21-Jun 30-Jun 25-Jun 17-Jun 11-Jun 1-Jun 9-Jun 22-Jun
Last 15-Sep 4-Sep 7-Sep 26-Sep 8-Sep 27-Aug 11-Aug 6-Sep 11-Aug
Green Hairstreak
Callophrys rubi
First 12-May 1-May 1-May 18-Apr 4-May 8-Apr 20-Apr 19-Apr 21-Apr 9-Apr
Last 14-Jun 6-Jun 6-Jun 8-Jun 7-Jun 13-Jun 6-Jun 15-Jun 13-Jun
White-letter Hairstreak
Satyrium w-album
First 26-Jun 5-Jul 17-Jun 24-Jun 25-Jun 10-Jun 5-Jun 5-Jun 30-May 23-Jun
Last 19-Aug 11-Aug 9-Aug 7-Sep 10-Aug 27-Jul 7-Aug 31-Jul 2-Aug
Small Blue
Cupido minimus
First 26-May 3-Jun 18-May 13-May 6-May 5-May 15-May 30-Apr 24-Apr 19-May
Last 19-Aug 2-Sep 13-Aug 2-Aug 13-Aug 11-Aug 7-Aug 4-Aug 8-Aug
Holly Blue
Celastrina argiolus
First 9-Mar 2-Apr 16-Mar 4-Apr 22-Mar 25-Mar 17-Mar 27-Feb 8-Jan 30-Mar
Last 24-Oct 19-Sep 9-Nov 8-Nov 31-Oct 6-Dec 23-Dec 27-Nov 7-Nov
Brown Argus
Aricia agestis
First 8-May 22-May 6-May 27-Apr 6-May 3-May 14-May 30-Apr 24-Apr 17-May
Last 4-Oct 26-Sep 5-Oct 1-Oct 2-Oct 27-Oct 25-Oct 23-Sep 28-Sep
Common Blue
Polyommatus icarus
First 9-May 26-May 1-May 4-May 1-May 5-May 23-Apr 20-Apr 6-May 18-May
Last 4-Oct 2-Oct 1-Nov 29-Sep 18-Oct 27-Oct 29-Oct 10-Oct 16-Oct
Adonis Blue
Polyommatus bellargus
First 20-Aug 8-May 27-May
Last 8-Sep 10-Sep
Chalkhill Blue
Polyommatus coridon
First 5-Jul 8-Jul 26-Jun 29-Jun 2-Jul 28-Jun 28-Jun 2-Jul 22-Jun 4-Jul
Last 18-Sep 18-Sep 15-Sep 19-Sep 24-Aug 1-Sep 1-Sep 12-Sep 10-Sep

The first and last sightings are gathered as the current butterfly season progresses so as to provide up-to-date information about species emergence. For previous years the first and last dates will be the actual dates as recorded on our branch database when they become available; empty entries indicate absence.

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