spiders web's or not ???

[onion man]

hi all i have got some cucumber plants in my greanhouse gut the other night i noticed they seam to be covered in like spiders webs and the leaves are turning yellowish and also turning up at the edges i have attached a photo
so can any one tell me what it is and how to get rid of it
and another short question can you keep tomatoes in the same greenhouse ??

[Two_Sheds]

Spiders are your friend

I have a little one in my kitchen window busy trapping & eating fruit flies. Same in greenhouse

edit: what you've got isn't spiders

[ddiogyn]

Glasshouse spider mite? Royal Horticultural Society | Advice Search | Glasshouse red spider mite

[taff]

you might have a spider mite infestation. Damp down the floor of your greenhouse and keep the air moist, they don't like it.

[Bigmallly]

I came across this but not sure if it's of any use.

Symptoms...................................................... Probable Causes

Leaves turn yellow. Silky webs on plant.......................Red spider mite
Leaves turn yellow. Small green insects...................Greenfly
Clouds of tiny insects............................................... Whitefly
Holes in leaves or stems. Slime trail.........................Snail / Slug
Leaves discoloured, plant collapses........................Root knot Eelworm
Grey fluffy growth on stems, fruit and leaves...............Botyritis
Leaves wilt, dark stem, plant dies................................Collar rot
Leaves mottled yellow, wilting...............................Mosaic Virus
Leaves turn yellow from base upwards......................Verticillium wilt
Sunken, oozing spots on fruit................................... Gummosis
Wet dark wounds on stems, leaves and fruit..........Sclerotinia disease