Thecla betulae L.           Brown Hairstreak

with regard to the search for eggs during the winter in order to map this species

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search for eggs


map of South-Germany

map of Germany

map of Europe

recent records

Further Hairstreak-species



According to the appearance of  Thecla betulae (Brown hairstreak) during the summer this species seems to be quite rare - during the last years I was able to observe only  3-5 butterflies a year. Since I have been looking regulary for the eggs during the winter, I've changed my mind : I found around my home town Bad Saulgau ( near Lake Constance, Swabian Jura, South-Germany ) and at many other places in a short time the eggs of this species - have a look at the following results of my mapping .

Do you want to look for those eggs   as well ?

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My special interest in this species results in these eggs - I find them easily during the winter, mostly on Blackthorn. Caterpillar of the Brown Hairstreak - half grown.


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Fully grown caterpillar of the Brown Hairstreak - ready for pupation (to be recognized by the dark colour)

Pupa of the Brown Hairstreak

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Female of the Brown Hairstreak, characterized by the orange spot on the brown upperside of the wings

The underside of the wings is very colourful !

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Blackthorn in spring !

Blackthorn in summer !

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Sometimes I find eggs of other species on Blackthorn in the winter, such as these with a very smooth surface.

Peter Waselius from Finland told me, that these eggs might belong to Plemyria rubiginata (= P.bicolorata = Blue-bordered Carpet) !

The picture on the left shows such eggs, the small in the left upper edge two eggs together with an egg of betulae.

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Search for eggs 1)   I almost exclusively search eggs at blackthorn (Prunus spinosa), since you find these bushes at many places und the search has been very successful. Further foodplants are mentioned later on.

2)  The search can start at the beginning of November, then the bushes have lost most of their leaves. It can be continued sucessfully up to April - providing more pleasure while strolling during the winter. Since some years I've been noting the lenght of time I had to search - on an average I had to search less than 5 minutes to find the first egg.

3)  The female lays the eggs nearly always at the spine bases or forks between twigs. Due to its whitish colour they are set off against the darker branches. The eggs are shaped  quite round (diameter 1mm) - using a magnifier you'll detect the nice structure of the surface of the egg (sometimes you can find another sort of white egg at blackthorn, which are shaped longish and have a smooth surface. It's recommended to use the magnifier until you have got enough experience in identifying the eggs.

4)  In  literature you can read that the females prefere older und bigger bushes of blackthorn. I cannot confirm that ! My search seems to be more successful at smaller bushes (e.g. single bushes at sunny edge of a wood) and at newer branches (0,8m - 1,5m)

5) Pictures showing the structure of the eggs in detail you can find at the site
European butterflies by Mario Maier ( choose "Metamorphosen" , have a look at | Links | as well )

6)  When you have any problems identifying the eggs send a message to me - I can offer you further aid  ( )

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It`s not quite easy to identify Blackthorn in the winter (when there are no leaves at the branches). The thorns (look at the picture left) are very typically, especially at younger branches (up to 2m). The branches are brown or black-brown, especially older bushes are looking quite dark (from the distance). If you find bushes with those blue berries the identification is not so difficult .

More about Blackthorn   here !

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Foodplants Foodplants recorded by myself

1) Blackthorn ( Prunus spinosa )
As mentioned above I've nearly exclusively been searching at blackthorn, because that bush ist widespread und the search has been very successful.

2)  Plum ( Prunus insititia )
In orchards you can find regularly eggs at the thornful braches of plum (especially when they run wild)

3)  Prunus padus
Just once I found two eggs at that tree.

4)  Prunus cerasifera
I found one egg at the end of 2000

Further foodplants mentioned in  literature

Birch-tree (Betula pendula)
Chaenomeles japonica
Prunus domestica
Prunus avium

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Map of South-Germany

Map without mapping-points

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Rot3.gif (898 Byte)New record since July 2000        Blau3.gif (898 Byte)New record since 1990
The map above uses the same system of mapping as   is shown in  "G.Ebert, Die Schmetterlinge Baden-Württembergs, Volume 2 , S.162 " (published in 1991)

Map of Germany

Map without mapping-points
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Rot3.gif (898 Byte)  New record since July 2000   Blau3.gif (898 Byte)Record since 1990

Map of Europe

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New records (since July 2001) 
Have a look at the  German Version of this page  !!
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1) Further species which can be mapped by looking for eggs in the winter

In principle all eggs of "Hairstreaks"-species  overwinter and can be looked for !

Purple Hairstreak (Neozephyrus (Quercusia) quercus)

Repeatedly I found the eggs of that species at oaks! According to the colour of the egg (grey-brown) it is not as conspicuous as that of Th.betulae. The eggs are laid at the flower buds.

Recent records

Have a look at the  German Version of this page  !!

White Letter Hairstreak (Satyrium w-album)

The striking eggs of that species I found just once.

Satyrium acaciae
Satyrium ilicis
Satyrium spini)
Black Hairstreak (Fixenia pruni)

There has been  no experience of mine searching these eggs till now.

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