Science Interviews


Thu, 1st Aug 2013

Why are so many daddy longlegs around?

Ian Burgess, Medical Entomology Centre, Stow cum Quy

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Chris - Ian Burgess is our special guest this week. Ian, tell us about these Crane fly or Daddy longlegsdaddy longlegs that have been seemingly appearing in plagues recently.

Ian - Yeah, there appear to have been a lot more than normal and as you said Chris, earlier they seem to be smaller than normal. In fact actually, this particular group of species does come out at this time of the year anyway.

We probably have also a slight sort of pushing around of the emergence because there are some species that have come out early in the spring. But because it was a relatively harder winter then they were delayed. But the most important thing is that most of the insects that we have in the UK really prefer to have a cold winter. Over the last 10 years or so, weíve had relatively mild winters. So, they havenít had, or rather the larvae in the ground or the pupae, depending on what stage they're at at winter time. They havenít had that sort of activity suppressing effect. So, they've been using up all their energy reserves much too quickly and many of them die before they get to the point of emergence. Having had a nice cold winter, they have all been nicely tucked up in their mud or whatever and so, they survived. And now, they've come out because itís warm and probably, weíre getting different species coming out that maybe wouldíve been more spread out. They're surviving much better because the conditions are nice and they're very active you see. Much more active than perhaps they would be if it was cooler weather now.

Chris - Are they the leather jackets that we see when you put your fork and then dig up your plants and you find something has eaten all the roots of your prized shrubs?

Ian - They're larvae of leather jackets, but the ones that you find normally are the big yellow and black ones and the sort of khaki coloured ones that weíre getting in the early autumn. These will have similar larvae, but they're smaller.

Chris - We heard from a gentleman from the RSPB who was talking about bird migration and why itís a major problem with things coming out of different times of year because birds normally time their arrival back in a country, in which they're going to breed, to coincide with when there's going to be lots of food for them to eat. If these insects that they would normally eat are appearing too early then the insects have been gone by the time the birds come, and then the birds donít have much food, and then their chicks donít have much food, and then you have a lower bird population.

Ian - Yes, so on other side of it is that of course, the birds can arrive too early because the things are being delayed. So this year, the house martins and so on, had a little bit of a rough time when they first arrived because the insects werenít coming out. In fact, they all nested rather later than normal because of that, because there wasnít enough to feed the chicks. Although they're all very hard at it now.

Ginny - So, what can we do to help the birds if the insects are coming out at the wrong time and we see these birds, and there's nothing for them to eat?

Ian - It depends how adjustable they are in terms of diet. I mean, things like robins and so on, although they're insectivorous, they will take seeds and stuff like that. But things like house martins and swallows that have to catch their food on the wing, there's nothing you can Ė unless you're going to get a big handful of insects and throw them up in the air at the right moment.

Dave - Breed lots of flies.

Chris - Is it true that there are lots of other insects, that are doing very well as well though, because my brother has taken up beekeeping and he actually came up to a village in Cambridgeshire and bought a colony of bees off of a man who was downsizing. Heís taken them back to London where he lives and he said they're doing so well a)  Heís got 40 kilos of honey in just 2 months and also, heís had so many bees, heís had to split the hive. So, they bought another queen and it arrive by post. This is quite interesting you get this parcel in the post instead of buzzing around in the place.

Ian - That's called a nuke.

Chris - Yeah and then you take some of the bees from the existing colony and put them with the new queen and off you go. But has it been a good year for the bees then because I've only seen one in my entire summer?

Ian - Well, I have seen other honey bees, but they're rouge ones so to speak, in that they are ones that have swarmed. They've gone off and they've then gone and nested in things like chimney stacks and roof voids.

Ginny - Yeah, my parents actually. their house, they have a nest of honey bees in their chimney and they got someone and asked whether they should do something about it. They don't really mind them being there, but they do fall down the chimney from time to time and then they're all sooty and confused, and they leave footprints all over the curtains. So, they asked if they should do something about this and the guy said actually no. Itís better to leave them there because if you move them on, theyíll end up with a load of honey dripping down your chimney which is actually a lot harder to clean.

Chris - Can't they light a small fire. Smoke does do things to bees.

Ian - Actually, they think itís a forest fire. So, what happens is that they all drink the honey as much as they can to rescue it and then they become torpid. This is how the beekeepers control them with the smoke guns so that when they're handling the stock then the bees are not too aggressive. They're actually suppressed by the smoke. But the trouble is when they're up in an awkward place, that can be a bit of a problem and certainly, you donít light a fire in the chimney where the bees are because you will literally get the honey fallen down and then it might catch fire as well.

Ginny - Well actually, these bees have been there for a good few years now and we have lit fires in that chimney and it doesnít seem to affect them. So, I'm not sure where they are, but they do fall down quite regularly, so they must be somewhere out there.

Ian - But itís not just the honey bees. Bumblebees have had a stunning year as far as I can see. I mean many, many nests. Weíve got a nest in our roof that's been there for 2 years and where I go for a walk at lunchtime, there's an avenue of lime trees and once you get far enough away from the road and you just stand underneath there, you hear constant mmmm. If you look up the whole tree, is alive with bumblebees.


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