Sunday, 7 September 2014

Caddisfly - Halesus radiatus

Before owning a moth light trap I had not really considered caddis flies as being a frequent visitor to the garden. But over the last few months I found a number skulking among the egg boxes as I empty the light trap in the mornings. Now I struggle enough trying to identify the moths that I catch and release, but caddis flies are even more of a challenge, as they do not seem to attract the attention of the publishing world resulting in a dearth of accessible field guides. There are over 6000 species that have been described worldwide. Of which 199 have been recorded in Britain, but only 3 in Ireland (1). I think that this chap who I found in the light trap a couple of weekends ago is Halesus radiatus, but I'm open to corrections.


Caddis Flies are superficially like a moth, and are a distant relative in the evolutionary sense,  but instead of scales on the wings, Caddisflies have a fine coating of hairs. It is this coating of hairs that gives this group of invertebrates it's name Trichoptera, meaning hairy wings. I think I've said this in another post, but as I get older I forget these things, and it's always worth repeating yourself - unless your wife or daughter are in earshot. It seems that caddisfies dont develop a wide range of colours unless it's brown! 



The larval stage provides the English name of Caddisfly. This is thought to derive from Elizabeth street hawkers called caddis men. The Middle English word caddice, means a woollen braid, ribbon, or tape. Caddice men used to displays these wares by pinning them on their coats. The aquatic larvae makes protective cases from materials picked up in the habitat, including  leaves, tiny sticks, sand and gravel. But not all caddisfly larvae makes cases, but all have the ability to make silk threads. I've not looked for any caddisfly larvae, but there may be some in the small pond we have, and it may be an idea to have a look. There is an interesting and accessible description of the life cycle of the caddis fly on the Fresh Water and Recorders Scheme website (2).


1: Nature Spot. http://www.naturespot.org.uk/taxonomy/term/19486. (Accessed 2014-09-08).
2: Fresh Water San Recorders Scheme. http://rasp.freshwaterlife.org/recorders/publications_resources/how_to/caddis/life-cycle.html. (Accessed 2014-09-08)