Catching Insects with Pitfall Traps

18 June 2006

Derek - Hello there and this week we've come to the Museum of Zoology at the University of Cambridge for National Insect Week. Of course, we are now in National Insect Week so we're all very excited about the science experiment we're going to do this week because we're going to be catching insects. And we're doing this with the help of one chap who's come to help us out. Would you please introduce yourself for us.

Ed - Hi my name's Ed Turner and I work at the zoology department here in Cambridge and also with the Wildlife Trusts.

Derek - Ok and I gather you set up some experiments to catch insects for us?

Ed - Yes, what we've done here is set up some pitfall traps to catch some insects.

Derek - Fantastic. We've also got some volunteers who have come along to help us out. So guys, could you give me your names and what school you're from?

Sam - Hi I'm Sam from the Perse.

Luke - I'm Luke, also from the Perse.

Derek - So do you guys like insects?

Sam - I've loved them since I was very very little.

Derek - That's absolutely fantastic. And yourself?

Luke - Yeah I like insects too.

Derek - So Ed, what we need to know is how to make these traps, because people at home can do this as well and they've been encouraged to do this over the past week. What do you have to do?

Ed - Well it's very very easy. All you need are some plastic cups and you need to find a patch in your garden where you can safely dig. Don'' dig up the middle of your lawn or anything like that. Just dig a small hole, put the cup in and make sure the surface of it is completely flat with the soil, so that any insects walking along can easily walk into it. What you could also do is put half a bucket over the top of it to protect it from the rain.

Derek - Obviously people might be thinking that they don't want to cut up their bucket at home. Is there anything else they can use to protect it?

Ed - Yes, absolutely anything. An old ice cream carton. Anything like that really.

Derek - And suspending it above the cup to protect it from the rain. How can you do that?

Ed - Well what I've done is use some bamboo poles but you can use anything at all to hold it off the surface.

Derek - Now we're actually at the New Museum's Site in Cambridge and we've set up some pitfall traps already, but what are the kinds of places we can set them up in?

Ed - What I've done here is to actually put some traps in the border in the loose soil. I've also put some beneath a hedge and I've put some into the lawns as well. I've had the permission of the gardeners here in zoology. You could do that if you're careful but you should ask your parents first.

Derek - Yes we must be careful to make sure that no-one decimates their parents' lovely lawn here. So just to recap what Ed said there, we've got four pitfall traps here in slightly different positions. One of the is on the lawn itself and the others are in the soil. One of them is in the shade, one of them is quite far away from the border of the lawn and one of them is close to that border. So why don't you have a go at home? Try and find out the different places you can put the traps and see what you get. And Sam and Luke are very keen to find out what's in these pitfall traps, but we're not going to find out yet. We're going to find out later in the show. Sam, what do you think we might have go tin some of these pitfall traps?

Sam - In the lighter ones you may find smaller insects than in the shade, because the shade gives them more protection.

Derek - Sounds like we have an expert here. Ed is nodding very impressed over there. And Luke, what do you think?

Luke - We might get some grasshoppers or flies or something.

Derek - Ok, and we will see all about that very soon. We encourage you to have a go at this at home, and if over the past week you've been having a go at this, then please tell us what you've found. If you're emailing, why not send us a picture. We will be back here at the Museum of Zoology very soon. Please do join us then and back to the studio.

LATER…

Derek - Hello there once again to the Museum of Zoology at Cambridge University and we are here with the result of our pitfall traps which Ed Turner from the Museum of Zoology and the Wildlife Trusts has set up for us. Sam and Luke are ready with their results so why don't we have a look. Ed, would you like to instruct Sam firstly on what to do with the cup which we've just taken out of its position in the garden?

Ed - We've got lots of stuff here so we need to pour it right in the middle. We've got a white tray here so we can easily see the insects we've got. We need to pour it right in the middle and things are already hopping out as we do that.

Derek - They are insects are they, Ed?

Ed - Well they're not really insects. They're very primitive insects. They've got six legs but they're not actually insects. They're called non-insect hexapods.

Derek - Ok, well tell me a bit about them then. They look to me as though they're about 3 or 4 millimetres long. They're crawling round a bit like ants but with longer antennae. What else can you say?

Ed - Well we can look at them and we've got some hand lenses here, which you can get from shops quite easily. They're very velvety, and I think Sam's just having a look now.

Derek - Tell us about it Sam. What can you see with the magnifying glass?

Sam - They're quite hairy and they've got a sort of stripe through the middle where there's a colour change.

Derek - And also, what are they doing?

Sam - They seem to be escaping. Occasionally they'll jump but they won't go too far.

Derek - What's all the jumping about?

Ed - Well that gives you a clue to their name. They're actually called springtails. They have a spring at the end of their tails, which is a little structure that looks a bit like an arm. They can straighten it very fast and will propel them into the air, so it's an escape response. The reason is that these things are eaten by nearly everything, so that's why they're a bit nervous and twitchy animals. Everything's trying to munch them.

Derek - So Luke, how about you pour some of one of your cups out onto on eof the white trays that we've got here. And Luke, where was that one from in the garden?

Luke - That was from the lawn.

Derek - So that was actually in the grass. What have we got here?

Luke - We've got a woodlouse, which is curling up.

Derek - Yes, I think I can identify a woodlouse as well. Ed, what can you say about that?

Ed - Well that's another very interesting response to predation here to escape predators and things that are trying to eat it. It's a pill woodlouse, so its response is to curl up a little bit like an armadillo and protect itself from predators.

Derek - Ok, so these things think that we are predators, do they?

Ed - Yes absolutely. They're in fear of their lives but of course they're not going to be harmed today; they're going to be put back afterwards.

Derek - Let's have a look at a third cup then. Luke, have you got another one there?

Luke - Yes, it was in the shade in the soil.

Derek - Ok let's pour that out then and see what you've got. What can you see there, Sam?

Sam - I think there's a young devil's coach horse.

Derek - Ok and describe that for me.

Sam - It's long and black. It's got six legs like your average insect but it's long.

Derek - Sounds like we have a real expert here. Ed. What do you say?

Ed - Yes he's absolutely right. It's not a young one but a different species. With insects the larvae are a bit like grubs with beetles. So it's a bit like a beetle. And you're quite right: it's a devil's coach horse, it's a rove beetle. Unlike most beetles that have these two big hardened wings cases, if you think of ladybirds, rove beetles actually have very tiny wing cases. The reason is that they can then move very easily between the soil or in cracks and often hunt for smaller insects, such as these collembolans, these springtails we've already seen.

Derek - One thing that occurred to me when Luke poured out that cup we got from the shady part of the garden is that we got a lot of insects in there. Is that what we would expect?

Ed - Yes, absolutely. What we've got here is lots of animals that are living around in the moist ground and in the mud and they don't like to dry out too much. This is maybe why we're getting more insects.

Derek - I am very impressed with the stuff we found here and delighted as well that it all did turn out fine. So Sam, what did you think of our list of insects here?

Sam - I think we definitely got more insects nearer the shade.

Derek - Yeah and you guys predicted that, so I can't take any credit for that. Well done to you. And Luke, how did you like the experiment that we've done?

Luke - Yeah it was good. We got lots of different insects, different types.

Derek - I think hopefully you at home will have heard that it's very easy to do, the pitfall traps that we've made here. You should do it at home and tell us what you find. And Ed, if people would like to get some more information on what they've found, what else can they do?

Ed - Well they can come along to National Insect Week at the Department of Zoology on the 24th and bring any insects that they can't identify themselves. We've got an Ask the Entomologist section, so an ask the insects expert section, so bring along all your stuff and we'll do our best to identify it for you.

Derek - And this is all at the Museum of Zoology on the New Museum's site, and maybe you'll even see the pitfall traps we set up here. Thank you very much to Luke and Sam and to Ed for setting up th experiment. I hope you have a very fun insect week looking for insects where you are. We'll be back next week and until then, back to the studio.

Ingredients

A plastic cup

A small trowel (something to make a small hole)

Somewhere to put the hole - eg a garden.

Half a bucket / Ice cream container (optional)

Instructions

All you need are some plastic cups and you need to find a patch in your garden where you can safely dig. Don't dig up the middle of your lawn or anything like that. Just dig a small hole in a flowerbed or under a bush.

Put the cup in and make sure the surface of it is completely flat with the soil, so that any insects walking along can easily walk into it. What you could also do is put half a bucket over the top of it to protect it from the rain and the sun.

Then leave the trap for a few hours, maybe overnight, come back and see what little monsters you have caught.

Result

Sam found a springtail - They've got six legs but they're not actually insects. They're called non-insect hexapods. They look as though they're about 3 or 4 millimetres long. They crawling around like ants but with longer antennae. They have a spring at the end of their tails, which is a little structure that looks a bit like an arm. They can straighten it very fast and will propel them into the air, so it's an escape response. The reason is that these things are eaten by nearly everything, so that's why they're a bit nervous and twitchy animals. Everything's trying to munch them.

Luke Caught a pill woodlouse. Its response is to curl up a little bit like an armadillo and protect itself from predators.

Explanation

You may find that traps in dark shady places work a lot better than in the sun, as insects feel a lot safer from big predators like birds.

If you want to identify the bugs you find you could try:

Exeter Universities Bug Club

Kendall Bioresearch's Insect Key

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