How to find eggs of the Brown Hairstreak

The Brown Hairstreak (Thecla betulae) is an incredibly beautiful species. Last summer, I had the pleasure to get some good shots of this butterfly. And it left me hungry for more.

For season 2015 I’ve set my priorities to get further engaged with hairstreaks. This includes raising a couple species from eggs to adult butterflies. Raising butterflies from eggs calls for one thing first: finding the eggs. Here’s some tips and tricks for getting started on the search for eggs of the Brown Hairstreak.

As said, last summer I got lucky seeing adults flying (and posing wings open). It was rather coincidence that I entered the habitat of the Brown Hairsteak, the largest species of hairstreaks in Finland, at the right time. It was the first time for me spotting this species. I had a great clue where to search for eggs later autumn.

Knowing a location where the butterfly is present is probably the best to get started. However, hairstreaks are often shy species and may remain unseen. In fact, some people search for eggs during winter as a sign of a species’s presence. This way they know where butterflies can be found flying in summer.

In Finland, Bird Cherry (Prunus padus) is the common food plant of Brown Hairstreak caterpillars. In my search I observed that most eggs are laid quite low on young growth of the plant. The growth ranged mostly from 1 to 2 meters in height, and the eggs were located in a height of ca. 20cm up to 1 meter.

Finding the eggs is not too difficult (assuming you’re on a good spot). The clean white dots area easily found. It’s mostly single eggs, but they can be found in groups of two or three. Forks in branches seem to be preferred spots, even though I’ve found eggs laid directly on a branch or the stock of the bush.

I’ve been checking the habitat during autumn and winter. Snow and frost definitely make it more difficult to browse through the growth. One more thing, while searching eggs I often found empty ones as well (see photo below). These eggs must have hatched earlier, and the eggshell seems to remain quite well. If you see a dark shade in the middle of the egg it may be empty. Hence, focus on eggs that are throughout in a clean white shade.

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