Garden infested with larvae - advice and help needed, please!

james_garley

Hi

I wonder if someone can help me as I am going out of my head with some larvae in my garden.

In September, we had a new patio laid and I did not cut the grass for around six weeks whilst the work was being done.  I am usually meticulous with my grass and it is a bit of a hobby for me, no weeds etc.  We live in a terraced house so only have a very small area of grass.

Once the garden was finished, I purchased a lot of ‘Patch Magic’ which is grass seed in soil and I used it to fill in loads of the edges where there was then just concrete holes.

About three weeks ago (end of November) we awoke one morning to find about 150 larvae crawling around on our patio.  We dustpan and brushed them all up, but they just keep on coming.  We had about two days where they did not appear and I thought that was the end of it.  However, as soon as it rains again, they all come out.  I have realised they come out of the grass.  They are most active at night so when it is dark and rains they come out literally in their hundreds.

In total, I must now have got rid of about 2,000-3,000 of these!

Please can someone tell me what they are and what I do?  If anything, more of them seem to be appearing!  Last night it rained heavily and at least 500 came out, maybe more.  I am spending every single morning and evening clearing these away and pouring them into our brown bin and am at the end of my tether.  I have applied two treatments of ‘Nemasys Leatherjacket Autumn Treatment’ as someone suggested they may be leatherjackets.  However, this has been down in the grass now for two weeks with no sign of them stopping.

I watered my grass a lot in the summer as it was very hot and dry for a long time and my grass was probably the only nice green grass in the whole street – I don’t know if this has anything to do with why this has happened?

I could really do with some help to identify what they are, how to treat them and if the whole grass just needs digging up.  Also – how do we stop this in the future?

I have attached photos to this message.

Thanks so much.

Dave Humby

Those aren't leatherjackets.

Dovefromabove

Can't see them very clearly but it looks as if you have a mixture of types of larvae and other invertebrates ... my guess is that by having a well-watered lawn in the dry spell you had the only patch of soft grassy soil in your area where moths, craneflies and other insects (some beneficial) could lay their eggs.

Now, when it rains the grass becomes sodden and the larvae have to come up to the surface for air or drown.

I would sweep them off the patio onto the lawn if you don't want to see them and try to attract as many birds as possible ... groundfeeders like blackbirds will love those little wiggly invertebrates.   Put some feed out in a container on the lawn ... seeds, chopped apple, suet etc ... the blackbirds will find it and then find the wrigglers. 

I wouldn't worry unduly ... the ones that don't get eaten by the birds will turn into moths etc in the spring, pollinate your plants and fly off to be eaten by bats and birds.

james_garley

Hi Dave

Thank you so much for your reply.  Any idea what they are?

It is driving me insane!

Dave Humby

james_garley said:

Hi Dave

Thank you so much for your reply.  Any idea what they are?

It is driving me insane!

I'm guessing a caterpillar or moth but the images are not really clear enough. I'm also not sure if they are the same beastie at different growth stages or different larvae altogether. The one's in the dustpan look different to the close-up images but that might just be the focus / lighting.

Dovefromabove

Some look as if they're caterpillars of one of the Underwing Moths ... they can be pests in the USA but are not usually regarded as such in the UK.  They pollinate our plants and provide food for bats hedgehogs etc.

This may be of interest http://www.wildlifeinsight.com/british-moths/large-yellow-underwing-moth-and-caterpillar-noctua-pronuba/

james_garley

Hi Dave

They are the same thing.  I'll attach another couple of photos, just the light that is different.

Question is - how or can I treat them?!

Dovefromabove

My advice is to leave well alone ... the problem will resolve itself with the changing of the seasons.  As I said, if they're on the terrace sweep them off ... attract birds to eat them.

There are no chemicals available to  gardeners that will kill them, and I'm sure you wouldn't want to poison your garden anyway 

james_garley

Thank you very much for the advice, guys

Allotment Boy

The caterpillars on the pale background  in the early pictures are cutworms. As Dove says these are larvae of moths,  these feed on roots & stems rather than leaves, there is more than one species of Moth that does this. The last picture is a leather jacket. I agree with Dove I think by keeping your lawn nice and lush in the hot summer all the local bugs have used it. There are some nematode treatments for leather Jackets and other biological controls but they will not work at this time of the year as it's too cold now. I agree try to let nature take care of it & hope for a good hard frost that & the birds will deal with most of them.

james_garley

Thank you.

So to confirm, are these in these pictures from last night, the ones that keep coming out at night and in the rain, leather jackets...?