‘I think you’ll find that’s putting the process rather simply, and they aren’t grubs. They’re larvae,’ he says.

I feel my face redden but keep my smile in place, even when the girl shoots me a smug look as if she’s caught me out. ‘I didn’t call them grubs. I said they were grub-like.’ Remembering the customer is always right, I add, ‘But thank you for pointing it out, sir. Both caterpillars and grubs are insect larvae, but they come from different families.’

A figure walks through the hanging strips of plastic and my heart sinks. My boss would have to turn up when I have a difficult customer. As usual, he’s wearing shorts that are a size too small for him. I don’t have anything against the vertically challenged – I’m one of them – but his tiny shorts only accentuate the fact that his hairy legs are disproportionately small for his body. To make it worse, he walks at twice the normal speed, like a mechanical toy that’s been wound up too tight. Right now his face is bright red, telling me he’s one angry outburst away from firing someone or having a heart attack. Possibly both.

Thankfully, Anorak Man doesn’t push the grub issue so I carry on speaking. ‘We have more than fifty species of butterflies and moths here at the centre. You’ll have noticed that they have lots of different patterns on their wings. Butterflies have many predators, and their wings help to keep them alive. Some act as camouflage, making it harder for them to be seen. Others have brightly coloured wings that are designed to make them look poisonous and trick predators into leaving them alone.’

I glance up and see another figure walk through the door. This one is tall and well built and wearing shorts that fit. Tom. He flicks his floppy brown fringe from his eyes, a rueful smile on his face, and lopes along like he’s just won a prize he can’t be arsed to collect. Tom is Mr Neeson’s nephew, which means he’s safe from getting fired, unlike the rest of us, and he often saunters in late. With his crumpled uniform, he looks like he’s just rolled out of bed. And he probably has. Tom is a gamer and often boasts about his latest weaponry haul to the other staff, so I imagine he stays up at night killing people. We all need a hobby, I guess.

As he walks by, he crosses his eyes and sticks out his tongue and I suppress a smile. Tom’s favourite pastime at work is trying to put me off whenever I’m giving a talk to the public. Yesterday he left a plastic cockroach on top of the display case, which I calmly placed in my pocket before any of the visitors noticed. I’m surprised he didn’t think to put one in my lunchbox, which he still hasn’t given back after our little game of hiding things last week.

I got him back by filling his half-empty water bottle with salt. He took a gulp while giving a talk and nearly spat it out over everyone. The shock on his face made me laugh so hard I had to hide behind a banana-leaf palm and take calming breaths. Maybe Tom sent the guy in the anorak to freak me out? No. He’s not that devious, or that smart.