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Miranda Hodgson

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Ladybird larvae come to the rescue

Posted by Miranda Hodgson on 12 Jul 2010 at 09:35 AM

Thousands of aphids have suddenly appeared in Oxfordshire. I can squish them, blast them with a jet of water from the hose or spray them. I don’t like spraying because it harms the beneficial insects as well as the pests, so generally squish or blast. As luck would have it, this year the predators have arrived at roughly the same time as the aphids and are saving me having to do much myself. They have come in the form of ladybird larvae. These are about 1cm long, though smaller when young, and have dark grey, segmented bodies with some orange spots down each side. They don’t look like ladybirds at all and can be seen in such large numbers that they could easily be mistaken for a pest themselves.



Along with ladybird larvae, the larvae of hoverflies and lacewings will also eat aphids. During a ladybird’s year of life, it can eat up to 5,000 aphids which makes them a welcome guest. Several parasitic wasps kill aphids, too, by laying their eggs in the aphids themselves. Looking at the underside of leaves affected by aphids, you may see a tiny, bloated, slightly metallic insect which never moves. This unfortunate creature has had an egg laid in its body by a parasitic wasp. Get a magnifying glass and keep an eye on it; in a couple of weeks, the new wasp will chew its way out, in a similar way to the monsters in the film ‘Alien’. I’ve wondered if that’s where they got the idea for that film, actually.

 

 

 

Aphids are a real pest, sucking the sap from plants and excreting sticky honeydew, with the result that the plant can be seriously weakened and, if not killed, the plants may be very distorted and bear few flowers or little fruit. They seem to appear almost overnight; one day the plants are fine and the next thing you know, stems and flowers are a mass of tiny, twitching green, brown or black insects. The reason they increase so fast is that they reproduce by parthenogenesis, meaning that they are born pregnant. When I was a student we were told that just one aphid, if left to reproduce without being eaten by a predator, would produce 10 million tons of new aphids within 100 days. Scary thought and it’s something I’ve never forgotten.

Quick update on the wasps

They are still building and I managed to get a couple of better photographs of the guard wasps on the outside of the shed. 

 

 

A male common wasp

 

 

 Common wasp, worker caste

 

 

Ladybird Survey - find information about ladybirds and record your sightings.

 

Comments

pushkin said:

Excellent post and photographs.  It sounded romantic when Shakespeare commented (was it on Titiana?) that she had fed on honeydew but he could not have known about aphids!  Glad the wasps are flourishing.

on 12 Jul 2010 at 12:05 PM

richardpeeej said:

Really good article Miranda-I have read the links you put in your post too. I hope I don't get any aphids on my runner beans Last year, the growing tips of some of them were absolutely covered in blackfly!

on 12 Jul 2010 at 01:12 PM

Miranda Hodgson said:

Ha, ha! I shall have to look at A Midsummer Night's Dream again, pushkin! What would Shakespeare would have said if he'd known what honeydew really is?

Fingers crossed for your runner beans, Richard! Washing them off with a garden hose works well; I've been doing that today with some rose buds that were thickly covered with aphids.

on 12 Jul 2010 at 04:48 PM

asj said:

Nice blog, Miranda!  Could you send a few of them my way, please?

on 13 Jul 2010 at 12:50 PM

Karin@Mintpark said:

Oh thanks for the post, I've just learned what's sitting on my plants, novice gardener that I am. I've been snipping the little black and orange things off leaves as I wasn't sure what they were and they do look a bit scarry, but now I know they're ladybirds in waiting I hope that they all made it back up. I'll leave them in peace from now on!

on 13 Jul 2010 at 08:49 PM

Miranda Hodgson said:

Hi asj, hope you find some in your garden soon - they're sure to be on the way!

So glad that this helped you, Karin. They do look a bit scary, but they're very nice really.

on 14 Jul 2010 at 12:57 PM

yvonne48 said:

I've been looking but can't see any larvae in my garden - very few ladybirds at the moment :(

on 18 Jul 2010 at 10:38 AM

Miranda Hodgson said:

They'll be along soon Yvonne, just you wait and see!

on 19 Jul 2010 at 10:48 AM

Miranda Hodgson said:

Despite the rain and chilliness of the last three months, ladybird larvae have appeared at almost the

on 20 Jul 2012 at 09:38 AM