Strange problem in shed

Hi chaps, during a rare clean out of my shed I noticed a patch of dark mess in a corner, I don't know how long it's been there and it brushed off quite easily - ie it was dry and crumbly. Looked like some kind of insect activity .... going out to look at the exterior it was quite dramatic, the back of the shed is difficult to get at and therefore not something I look at very often and it was difficult to photograph but a lot of black blotches and 'trails' almost like the ones slugs leave and a fair amount of web like stuff similar to spiders webs ... anyone any ideas please ?

There have been a lot of reports of caterpillars which hatch in large numbers and are in webs for protection - could it be something like that, the black being the caterpillar drippings?

hi it looks like you could have had tortrix moth caterpillars they make a large web to protect them from predetors the caterpillars are blueish  with black stripes running down them    jezza