Thursday, March 10, 2011

Hazel catkin galls

Now, with the weather improving, is the time to walk out and look for galls on hazel buds and catkins.

In my garden and round about, practically every hazel bush has big bud galls made by the mite Phytoptus avellanae.

20110309 SV Phytoptus avellanae 1

A more detailed search quickly revealed some galled catkins.

20110309 Contarinia coryli on hazel 016

The unopened brown catkin on the right has been attacked by either the mite Phyllocoptes coryli or the Cecidomyid midge Contarinia coryli.  The only way one can tell which species is responsible is by picking them apart and looking for the mites, which are minute, or the small white grubs of the midge.  I quite quickly found midge larvae - little white maggots - but have not found any of the mites yet.  They are very small though and will need a microscope.

Galls like this (the only two found on hazel catkins in Britain) are probably common throughout Britain, but rarely recorded, so if you come across any, don't forget to send records in.

The nut bud moth (Epinotia tenerana) also lives, in its earlier instars, in hazel catkins before boring its way into hazel buds to complete its development.  It is also widespread in Britain, so that' another one to look out for.

No comments: