Thistle gall

Last Sunday five of us finished the job started in July, scything a section of the top meadow to promote wild flowers.

The cut grass, lying in windrows here, was raked up and stacked to prevent it from acting as a mulch to fertilise next year's grass. . . . .

 . . . . unlike the grass cuttings in the neighbouring field next to the Leisure Centre

Peter, Chris, Will and Eric still smiling after two hours of scything.

 

Several of the thistles we cut had these swellings on the stem.

This is a gall caused by a rather beautiful insect - the thistle gall fly, Urophora cardui, which specialises in this.   The fly is only 6-8mm long and is on the wing in August and September.

Photo: QE Diamond Jubilee Wood

We cut open one of the galls to see what was inside but the larvae must have been very small as we couldn't see anything.  They fatten up during late summer and overwinter inside the gall, emerging the following summer.