I have an infestation of asparagus beetle - and I have only myself to blame for not looking out for it. I knew it existed of course but it didn't occur to me that it might find MY asparagus. I vaguely noticed that the plants were going a bit brown - but I didn't stop for a closer inspection as I assumed they were just dying back for the autumn. As a result some of the plants are virtually done for. I hope they recover. We haven't even eaten any ourselves yet, as I only planted the crowns last year and we're not supposed to harvest it until next year.
The beetles themselves are quite pretty - the size of an elongated ladybird, black and brown with white spots. But the larvae are nasty little grey maggoty things, which squidge out asparagus-coloured goo when you try to pull them off. I have spent a couple of hours hunting them all down and dropping them all into a jar of soapy water, which dispatched them pretty quickly. I will have to keep checking and removing them every day from now on, and next year of course I will be much more vigilant.