Working in Entomology

Professor Michael Majerus talks to Rachel McLeod

Published short version

I chose to interview Mike Majerus because he is the President of the AES and he also does lots of work on butterflies and ladybirds. The current experiment he is doing on ladybirds is collecting lots of pupae and then letting them hatch and keeping a total of how many harlequins hatch and how many 2-spots hatch. Harlequin ladybirds are foreign, they were introduced into other countries to try to control aphid numbers and have somehow travelled to England . They are doing extremely well, much better than the native species. To find out more about the harlequin ladybird invasion you can look at the website http://www.harlequin-survey.org.

The main reason the pupae don’t hatch is the scuttle fly that specialises in laying its eggs in the pupae of ladybirds. They have discovered that the flies don’t like harlequin ladybirds, but they are gradually starting to use them more. The scuttle fly will always choose the bigger pupae, but not if it is a harlequin, even though they are bigger than the 2-spot ladybirds and most other ladybird species. Over a period of 5 years there has been a change between no harlequin being attacked by scuttle flies to 3 in every 50. Mike is trying to find out a reason why the scuttle flies don’t tend to lay their eggs inside harlequin chrysalises.

Harlequin ladybirds over-wintering

He is President, I think, mainly because he is an experienced entomologist who knows what he is talking about, and a good communicator. He is also a professor at the University of Cambridge .

Rachel and Mike in front of some butterfly cages housing Heliconius butterflies

What insects do you keep?

We have an awful lot of ladybirds; so we breed greenfly, specifically because that’s what the ladybirds feed on, and we also have some butterflies and moths. The moths tend to be British, and we work on what’s called melanism, these are the moths that turned black or darker after the Industrial Revolution, as a consequence of pollution. They’re now going back the other way. So most of the moths are British, but the butterflies are mainly from the tropics, either from East Africa – we work on a genus of butterflies called the Acraeas, and then we also have butterflies here from Central and South America – these are mimetic butterflies and the genus is called Heliconius.

Some of the ladybirds harvested in mike's office, with aphids in the fore-ground

If you were to keep only one insect, which would it be and why?

The thing I would choose would be the Indian Moon Moth, and there’s a reason for this: when I was a kid, I used to go along to the AES exhibition, to buy the caterpillars of the Indian Moon Moth when they were very small, and they’re little sort of bumpy red caterpillars when they’re very small, they turn bright green later, and they feed on rhododendron, so they were quite easy to breed and the nice thing was, because rhododendron is an evergreen, you could breed them throughout the year, and if you bought them at the beginning of October they would hatch just before Christmas, and then these beautiful, pale green, big-tailed moths, I used to put them on our Christmas decorations, alive, every year. And it was great. As long as you left the light on in the room, they wouldn’t fly. I would hate it if you made me have only one insect, but if it had to be, I think I would go for the Indian Moon Moth.

Indian moon moth

What is your favourite place to go field collecting?

Oh, that depends what sort of mood I’m in. If I’m in a ladybird mood, I think it would be Chobham Common in Surrey , which has got lots and lots of great ladybirds. We’ve found three quarters of the British ladybirds on just that one site, which is pretty amazing. But if I was in a butterfly mood, it would have to be South America, somewhere on the eastern side of the Andes in Ecuador . It’s staggering – you can walk down into a montane rainforest there and you just never want to leave. You just see new things, amazing things, you go from the big Morpho butterflies, these bright iridescent blue butterflies to tiny, tiny little skippers flitting around, and then the little blue lycaenids feeding in little clusters on minerals coming out of the seepage coming out of the rock, that sort of thing. And it’s just the most fabulous place in the entire world, as far as I’m concerned.

What’s the most exciting thing you’ve done?

There is nothing more exciting than flying off somewhere to the tropics and the first day you walk into a tropical jungle that you’ve not been to before. I can feel my heart beating as I go off, I’ve got my net and I’ve got my stick, and what am I going to find?. I love it!

What do you think is the best way to get people involved in entomology?

Talk to them, show them things, tell them how fabulous these things are, how important they are. Some of them are pests, but, you know, if you took away the bees, we wouldn’t have any flowers, or, we wouldn’t have any pretty flowers. Very few. There are a few that are bat-pollinated or bird-pollinated, but bees are so important in pollinating stuff, and we wouldn’t have fruit. There’s so many things we wouldn’t have – if you took the insects away, we would lose most of our birds. Some birds feed on seeds, but the majority of birds feed on invertebrates. You know, if you just think about your garden, the blue tits, the great tits, the robins, the wrens and so on – these are eating insects. That’s what they feed their young, that’s what they need themselves.

Most people think that moths are nasty because they eat clothes, explain to them that of the over 2,000 species of moth in this country, you can count the number that are likely to eat your clothes, and it’s actually the caterpillars that do that, on the fingers of one hand. So the moths that they see coming to the lights in the bedroom and so on, these are not clothes moths. These are just good moths and they should leave them alone, not kill them, put them out of the window if they don’t particularly like them, but explain things to people properly. The science for most things is not that hard, and if people really understand about insects, then okay, there’s one or two that you would rather do without. The vast majority of insects do no damage and they are an incredibly important part of our natural ecosystems, and without them we’d be really stymied. We’d be in a real mess.

Are you scared of any arthropods?

There are one or two I don’t like in my home, and there are one or two that I will go quite a long way to try and avoid, that is, take precautions. So if I’m walking through the jungle in South East Asia or Northern Australia I will have quite thick jeans on, with my socks up over the jeans, and I will wear elasticated shirt cuffs and so on, and make sure everything fits tightly around with a belt, and the reason I do that is I don’t like getting bitten by leeches too much. There’s nothing wrong with it, they don’t hurt. It leaves you bleeding for a long time, because they actually put in a chemical that stops your blood clotting, and so on, so you get very bloody socks if one gets in. Leeches don’t carry disease, so they’re actually not too bad. Some ticks and some mites do, so those I’m also very keen to avoid. And there are typical things, I don’t particularly like horseflies, because I react quite badly when horseflies bite me, but I’m certainly not scared of them.

What’s the most embarrassing thing that’s happened to you?

So. This was in Panama . It could have been incredibly embarrassing. Fortunately I was entirely on my own. There was a particular plant that some of my Heliconius butterflies feed on – they come to take the nectar. And I wanted a photograph of this, and I was on the Dividing Range that goes from the Rockies all the way down to the Andes . I was on a path there and I found this absolutely perfect flower that was just at the right stage for a photograph. So I got my camera out of my rucksack, set up, and I was just about ready to take the picture when I felt a bite on my leg, a little bit below the knee, and then another one. And so I looked down, and very stupidly I was standing on a trail of army ants, which had been going straight up my boot, and then up my trouser leg, and they were biting. And they bite pretty hard, this particular one. And I reckon it was about 30 seconds before I’d stepped just one metre to the side, because then you’re off the trail, and to when I had no clothes on at all. At which point I could shake all my clothes, you know, first get the ants off me, and then shake all my clothes and get dressed again. I kind of felt, ‘Oh God, this is a bit crazy’. And ever since then, whenever I’ve set up to take a picture I always just check what I’m treading on. I got about 100 bites, so it was quite a painful lesson to learn.

What do you think would happen to insect populations if we suddenly disappeared off the Earth?

I think there will be a huge change, but gradually – it may take a hundred, 200, 300 years – things will stabilise down and we’ll get into a more balanced ecosystem than the one we’re in at the moment, which is very rapidly changing because of what we’re doing. So take us away and eventually things will settle down again.

Why is entomology important to you?

Because I think it should be important to everyone. We face incredible problems with the world, whether you’re talking about global warming or pollution or loss of biodiversity, or there just being too many people. All these things will have an impact on insects, and because insects are such an integral part of ecosystems, eventually it will come back and have an impact on us. Let’s take one example, mosquitoes. We need to understand mosquitoes because they vector, they carry, lots of diseases and particularly, the famous one of course is malaria. We don’t have malaria now in this country. But if temperatures increase through global warming, we are likely to get malaria back in this country, because we will get the mosquitoes that carry it, back in this country. We need to understand the role of insects in ecosystems as a whole if we’re going to make sensible decisions about our future and the future of this planet.