What is this bug?

[David P]

These destroyed half of my spuds last year.

I had a clear out of the stuff on my computer and found a picture that I had taken. When you pick up the potato, either half of it is missing or there is a hole like it has been jabbed with a biro.

It is clear to white in it's body, segmented and with legs. It has a head and is about 3mm long. There is a strip of blood/guts down the length of it's body.

Location? Inside the spud! Seriously, I moved to a place in Devon and the allotment has not been touched in years. I have never seen the like before but then again, I have probably unearthed all sorts of things.

If you get in touch I can post you a better picture.

Many thanks

David

[SarzWix]

Euwgh!! They are disgusting...! A quick Google search suggests they might be Wireworms, or maybe Cutworms:

Wireworm
Shiny, yellowish-orange, stiff-bodied and up to 25mm long, they spend four years in the ground before pupating for three weeks and emerging in the summer as adult Click Beetles. They feed on plant roots and bases of stems ruining potato and other root crops, making tunnels about 3mm in diameter which can later be invaded by slugs or millipedes. Lift maincrop potatoes before September, when the main damage is done. In the lawn they can weaken the grass, but are not usually a problem. They are usually widespread in grassland so will be found when it is brought into cultivation. After about five years of cultivation they usually disappear.
Treatments
Crush any wireworms that are found, though they are quite resilient.
Cultivating the soil exposes them to birds.
Lift crops from infested ground as soon as they mature to avoid damage.
Traps can be made using chunks of potato buried in the ground attached to skewers for easy removal; hopefully the wireworms tunnel into the potato which is then picked up and destroyed.
For a biological control the nematode Heterorhabditis megadis will attack wireworms. It is temperature sensitive so can only be used when the soil is at or above 12 C. The best time to apply is in August or September when the wireworms are hatching. Application may have to be repeated the following year due to the long lifecycle of the worms.
An infection of a fungus called Metarhizium anisopliae is known to kill both adult Click Beetles and wireworms so is being evaluated as a boilogical control.

Cutworm
Agrotis spp.

Cutworms tend to cause damage in hot dry summers in unirrigated crops of potatoes, when they feed on underground stems and tubers. The most damaging UK species is the Turnip moth Agrotis segetum. Adults fly from May to June and lay eggs on the foliage of potato plants. Caterpillars, which can be up to 35 mm in size, are greyish-brown with a slight yellow or pink tint and darkish lines along the back. They feed on the haulm initially and then drop from the plants to feed the underground parts. Some will pupate in July/August and produce a second generation of moths, but most overwinter in the soil as caterpillars, pupating in the spring to emerge as adults in May or June.

[Protea]

Definatley wireworm - cutworm are bigger. the damage you describe is typical of wireworm too. Many of mu spuds were eaten by the blighters last year too, its very frustrating

You say it was an old allotment, unused for years? Wireworm are particularly bad on areas that have been under grass for long periods. Try a mustard green manure and dig it in before planting (google for biofumigation) sow as soon as you can - early March if you're in Devon, you won't get a huge crop but if you plant your spuds later you might be able to reduce the wireworm population a bit to get a better potato crop.

They will reduce in time.

[David P]

Hi Folks

I don't think that it is either of them. cutworms seem to be far too big and wireworms are yellow - that's the wrong colour.

Any more guesses? I have never seen anything like them.

Keep at it

D

[David P]

I have just found this on the Bayer website. It could be the Flat millipede
Brachydesmus superus - what do you think?

Have a look at Pest Spotter - Flat millipede or google it.

Your thoughts please? It's not quite the same...

D

[Nicos]

David- where abouts are you???( I presume uk but you don't say on your profile)

What type of soil do you have- are you rural or suburban???

Might help with working out what it is!

edit..just realised you are in Devon!!

[NSB]

They look like baby woodlice!!!

[Two_Sheds]

I am 99% sure they are baby woodlice. We were plagued with them last summer, it was so wet and ideal for them to proliferate.
they ate everything that the slugs started on first

[David P]

Which ones? Make sure that you are looking at the first picture!

D

[sewer rat]

Which ones? Make sure that you are looking at the first picture!

D

David
Only gt one picture to look at - should there be two ?

[David P]

There be two pictures. One on my initial post and then another on a follow up post. It is the former.

When I think about it, they do look a little like pill bugs. The body shape is slightly different though...

D

[Two_Sheds]

I still think they're baby woodlice...catch some and grow them on, see what they turn into !
here's a good site for bug identification, but they don't have babies on there..
Common garden creatures

[Nicos]

I've looked through all my pest books and come up with nothing- sorry David

Why not send a photo to GYO magazine if no-one comes up with the right answer here???

Bound to be a baby of something simple too
I've never seen a baby chuggy pig, so I couldn't comment on that!

[terrier]

Try this site

BBC - Gardening - Pest and Disease Identifier

It's a question and answer with pictures and explanations, it may help to ID the problem bug.