The Colorardo Potato Beetle is a fascinating insect, and although it is not native to the UK, I once found one, and that event, and all that followed inspired this post.
Colorado Potato Beetles are striking in appearance, around the size and shape of a ladybird but the wing cases have alternating black stripes with bands of orange or yellow, running along their length. There are usually 5 black stripes on each wing case and this gives rise to its other name: the ten-striped spearman.
This distinctive little beetle is native to Mexico, and the southern US including the state of Colorado. It is primarily seen as a pest by humans, as it feeds voraciously, breeds vigorously and is commonly resistant to pesticides. The food plants of choice are, as the name suggests, are potato crops. However these beetles also feed on tomato and aubergine plants and a native crop called the ‘buffalo bur’. A heavy beetle infestation can cause significant damage to the plant and may even defoliate an entire crop.
So why I am writing about a little stripy Mexican beetle? We do not have Potato beetles in the UK, we do however have a lot of potatoes. Potato crops are a large part of the farming industry in the UK. Over 6 Million tonnes were produced in 2017. (Reference)
The beetles can breed up to three new generations during one potato growing season, and therefore one beetle can quickly become hundreds. The threat of potato beetles arriving in the UK is real, and thus they are a Notifiable species.
What does notifiable mean?
If you find a potato beetle in the UK you are legally required to notify the government. This is what happened to us. I found a potato beetle in a packet of spinach leaves. The amazing thing about this is that we even knew it was a potato beetle. I love wildlife and the natural world, but I won’t pretend that I can identify, on sight, every species of beetle from around the world. The kids have a board game called bug bingo*, and one of the ‘bugs’ on the board is a potato beetle, so even the kids recognised it immediately when we found it.
The spinach leaves had come from Spain, so I did a little googling and it was only then that I discovered that they are a notifiable pest in the UK. Having worked as a vet in the UK shortly after the Foot and Mouth Disease Outbreak, and BSE, I was aware of notifiable diseases but I had never reported an insect before!
These beetles are hardy. I mean really tough. The one I had was still alive and crawling around despite having been refrigerated, and enclosed in a bag for days.
When I notified the government, at my local office in Perth, by email. I sent a photo and asked what to do next. The office sent down a member of staff to identify and collect the beetle and remove it. He told me that these beetles, despite originating in warm tropical and temperate climates, can actually withstand freezing. Specimens have been stored in the freezer and yet quite happily started walking around again after defrosting. This is what makes it such a threat to the UK potato crop. Beetles which ravage potato plants, can produce numerous offspring, may be resistant to pesticide and can also survive our colder winter weather could cause a serious problem. The best way to protect against them is to prevent them coming into the country.
Biosecurity is so important and the potato beetle is just one example. We import many food stuffs from the continent that may carry a beetle. It can occur with any of the usual crops on which potato beetles feed, but also on crops sown in a field which grew potatoes in a previous season.
The beetles mate before overwintering in the earth, this means that a female emerging from the soil in spring is likely to already be carrying viable eggs, and able to lay them when she locates a host plant. So it only takes one female carrying eggs to get in to the UK to establish a colony, hence the vigilance.
If you find a Colorado beetle, in the UK, you must notify the government. I have attached the relevant contact details here, along with an identification guide, just in case.
*Our family enjoys ‘Bug Bingo‘ and would recommend it, particularly if you have budding entomologists in your house. Easy enough for younger ones to play and enjoyable enough for the whole family together.