[Crumble]

Hi All,

I'm new to the site and to growing my own veg.  I have a caterpillar problem I hope you can help with.  I'm growing Swiss Chard amongst other things and it is growing nicely however I have noticed a discolouration on some of the leaves.  On further inspection  I have found some sort of caterpillary maggoty thing inside the leaf membrane it is eating the inside of the leaf but leaving the leaf membrane intact.  Any ideas what it is and how to get rid of it.  Have tried searching under caterpillars but can only find reference to your 'normal' whole leaf eating varities!

Thanks 

[mumofstig]

Is it leaf miner?.....have a look here

http://chat.allotment-garden.org/index.php?topic=38741.msg461319#msg461319

[Salmo]

This is beet leaf miner. Only if the plants are very small with just 2-4 leaves are they likely to be killed or severely checked and that needs several maggots per plant to be damaging.

Because the maggot is protected inside the leaf you will not be able to kill it using either chemicals or organic soap solutions etc. To kill the maggots you can squezze them inside the leaf but it is probably not worth it. Just discard the damaged leaves.

When the maggots have fed for about 10 days or so they drop into the soil and pupate.
There may be a second or third generation but these will probably only affect the outside leaves. The last generation of the season pupates in the soil until next Spring when the fly reappears to lay its eggs on young plants of chard, beet spinach, beetroot and others of the same family such as sugar beet and mangolds.

Good rotation is the solution for farmers and market gardeners but is little use on allotments as the flies can easily fly 100 yards or so to find new crops. Good cultivation of the soil to expose the pupae to the eliments and birds is probably all that you can do. You could keep your chard covered with fleece or mesh but it is probably not worth the bother and expense.

[Kristen]

"When the maggots have fed for about 10 days or so they drop into the soil and pupate"

Would cardboard discs, or similar, prevent them getting to the soil and pupating?