[Russell Atterbury]

Many of my lovely sweet peppers keep having holes up to about 10mm chewed through them, and inside is left a black goo that is probably the creature taking a dump inside them. I can only think of ants, but I don't notice a lot of them, or any other thing, other than beneficial flying insects. Any thoughts on what the problem could be, maybe it's not a pest, but disease.

[Yorkie]

I've not known ants do that before.  Sometimes caterpillars leave behind poo.

[Subversive_plot]

I agree, it doesn't seem like ants (which often are looking for sugary substances on the exterior of fruit or plants, i.e, something liquid).

Caterpillars would also be my first guess.

[Kleftiwallah]

Are you sure it's not Dek's!  I'll get me coat.

Cheers,  Tony.

[Ema]

I’m also having the same issue, a little hole that looks reasonably innocent but then the inside starts to rot. I thought it was little slugs and finally gave in an put some organicy slug pellets down

[Russell Atterbury]

I'm going to keep a more vigilant watch over my peppers, I can only say that whatever it is must sneak in and out again pretty darn sharpish, because until now I haven't got a clue. I don't see any slug, or even ants anymore.

[New shoot]

Tomato moth attack peppers as well.  They are fairly large brown caterpillars and seem to hide on the stems during the day.  They eat tomato fruits and also peppers.  With the peppers, they chew a hole into the top and then the whole fruit starts to rot and die off once they eat a bit more.

If you can, shake the plants over an area of clear floor and be ready with your stomping boots 

[Subversive_plot]

Tomato moth attack peppers as well.  They are fairly large brown caterpillars and seem to hide on the stems during the day.  They eat tomato fruits and also peppers.  With the peppers, they chew a hole into the top and then the whole fruit starts to rot and die off once they eat a bit more.

If you can, shake the plants over an area of clear floor and be ready with your stomping boots 

We call those "tomato fruit worm" here, and those are the type of caterpillar I was thinking of in my earlier post. Yes, they are a pest on tomatoes and peppers.  I recommend a Bacillus thuringiensis based treatment, available as a liquid concentrate or as a dust application (both organic-compatible, I think).

If you do the "shake and boot" treatment New Shoot describes, I call those "flatworms".