Butterflies in the Stevenage area

Species Accounts

Each species found in the Stevenage area since 1993, is described under the following headings:

General Distribution and Status: The current range and status of the species in the UK and how the species has fared in the past. Explanations are given for causes of gains or losses and most are well understood but some are open to conjecture. A brief summary of the state of the butterfly in Hertfordshire and Middlesex is also given. A table is provided for state of distribution and abundance at both national and branch (Hertfordshire and Middlesex) level. An '*' (asterisk) in any entry indicates that not enough data is available to perform the appropriate calculations.

Habitat Requirements: Where the species is likely to be found.

Larval Foodplants: Only the primary foodplants are given here.

Adult Food Sources: The flowers most likely to be visited for nectar for the butterfly. Other food sources like aphid honeydew will also be mentioned.

Historical Records: Records for the Stevenage area prior to Brian Sawford's survey in 1984-86. Any significant records elsewhere in Hertfordshire may also be mentioned.

Local Distribution and Abundance: The state of the butterfly in the Stevenage area (TL22 decad) illustrated by a distribution map. References will be made to tetrads within the TL22 decad. Each tetrad is denoted by a letter, starting with 'A' at the south-western corner, for TL2020 and ending with 'Z' at the north-eastern corner, for TL2828. Presence of a species is indicated by a small dark green circle for 2020 until 2022, blue square (the darker it is the more common) for 2010-19, lavender unfilled diamond for 1995-2009. If a tetrad is blank, then the species has not been reported here since before 1995. The TL22 map courtesy of © OpenStreetMap.

The Records/Abundance chart is only a guide to the number for the associated species found on each sightings report in the area so it is not only transect data (which is the most accurate method of measuring abundance) which is represented. Possible reasons for fluctuations in numbers and changes in range will be explained and are open to conjecture. In most cases they are due to the vagaries of our weather and the quality or quantity of the habitat. The best sites to visit are noted. Weekly totals and phenology charts are shown for the three transects covering Stevenage and Knebworth. A grey square indicates that the transect was not walked in the corresponding week. The highest annual totals are highlighted in yellow and the best weekly counts in orange. Below show the annual transect totals for each species.

Life History: A brief summary of the species' life cycle. The earliest and latest records of adult sightings are listed. A phenology chart of the butterfly's flight period(s) covering the transect period from April until the end of September is shown. Week 1 starts on 1 April, week 2 on 8 April and so on until week 26 on 23 September. A phenology chart is shown for records incorporating abundance submitted in the TL22 square since 1995.

Behaviour/Observation Notes: Things to look out for when out in the field and the best times of the day to take close-up photographs. Behaviour of the sexes are different and may be explained here like male territorial activity. Also provided are distinguishing features for look-alike species.

Variations and Aberrations: Any notable variation or aberration worth searching for. Historical sightings relating to Hertfordshire or neighbouring counties are disclosed.

References: Any names highlighted in dark grey in the text will be cited with details listed.