Swarms of flying insects are plaguing beachside towns in patio scenes that some liken to a 'horror movie”.

The sudden influx of cockchafer beetles from Bay of Plenty to Coromandel has hatched lines and lines of debate in online forums about the nature of the pesky invaders.

Entomologist Ruud 'the Bug Man” Kleinpaste says chafer beetles – a group name for a number of types of beetle – are all over New Zealand this time of year, and the wet weather is encouraging them.

'I had hundreds of them in my home in Christchurch.

'A lot of rain or any moisture brings them out, but that is because at this time of year they are hatching from the soil, so softer, wet soil makes this easier.”

As to why they swarm in their hundreds at night, Rudd says it's part of their mating process.

”They are swarming around at night, having their fun, having a party, looking for a partner. Then its boy meets girl and away we go.”

Pāpāmoa woman Joelle Waterhouse captured what she called 'a plague” of the beetles on video.

'I've never seen them swarm like they did this year. They're attracted to the light as the swarm only came as the outside light went on. I know these beetles well as they come every year at this time. We call them Christmas beetles in South Africa, for that very reason, but I have never seen such an abundance of them.”

Joelle says the recent wet weather may have attracted more of the critters.

'In Africa we get summer rains from the humidity every day, and out in the bush where there is no light, you get swarms like this as soon as a light does go on. I've seen the odd one inside since then, which is normal, but I haven't had the external light on for an extended period since then.

Joelle says that in the last week, others in the neighbourhood have also had 'swarms”.

'Maybe they had all hatched that week.”

One Bay of Plenty woman says they are 'frightening” and asked on social media if others in Pāpāmoa and Mt Maunganui had 'infestations”.

'After we put on our external Christmas lights a plague of orange hard backed flying insects. Eventually they landed in the bush under the window, but others were still swarming about ... The numbers were quite frightening.”

Tracey Maris says they are Christmas beetles and are attracted to light.

'We are part of the Christmas lights trail, so the house is very lit up. It can be really embarrassing once it gets dark, and they are flying into people.”

Riley Gray also has hundreds of the Christmas visitors.

'I left the lounge slider open and came back last Sunday night and my Christmas tree was covered in them. We sprayed them and several hundred within half an hour had come inside.”

Whangamatā locals also said they had been 'invaded”, with the bugs clinging to washing, and 'invading” houses in their thousands, says yoga teacher Soreya James.

'It was like a horror movie the other night, hundreds of them on my kitchen bench and flying around inside.”

Manaaki Whenua/Landcare Research entomologist Darren Ward says the insects are not uncommon this time of year, but that the humidity may be bringing more.

'They are a beetle, commonly known as a Cockchafer. They are to the bright green shiny Manuka beetle which is commonly seen.

'Normal this time of year, and can be really abundant; given all the rain and warm weather its ideal for insects. They are not harmful and will be gone in a few weeks.”

The beetles have been in New Zealand for decades and are not a biosecurity risk, he says.

'They are indeed common at this time of year and are attracted to lights in large numbers. They are originally from Australia, but have been present in New Zealand since the ‘90s.”

-Annemarie Quill/Stuff.