Have any died? I'm assuming it was fresh pineapple (as any heating deactivates bromelain, the enzyme that breaks down proteins). If you put some fresh pineapple juice on your face or forget to wipe your cheeks after biting into a fresh pineapple, in about 10-15 minutes or so you will feel your skin begin to burn and start to turn red after a little bit, this is the bromelain attacking the protein in your skin... it is not pleasant. Try pouring some pineapple juice on a worm and tell me what happens after say 20 minutes... I'm quite curious. I would do it myself except that I rarely juice pineapples these days.

EDIT: So I just did a really quick Google and brought up the first reference to help explain what I'm referring to http://simpsonstreetfreepress.org/AAA-pineapple-enzyme

Also I believe the issue with oranges isn't the juice or pulp but its the oil contained in the rind of the fruit, which is 90% d-limonene which is a skin irritant... and apparently a neurotoxin in earthworms according to this article http://www.sciencedirect.com/science/article/pii/004835759090009Q from which I've taken this quote "...chronic and acute intoxication involved a rapid and predictable cascade of behavioral and morphological symptoms, including increased mucus secretion, writhing, clitellar swelling, and elongation of the body. In addition, chronic d-limonene exposures induced significant weight loss..."

I have tried fresh pineapple with know observed ill effects.

Did the worms eat it right way or wait several days before coming into contact with it? If they waited a few days first then maybe the bromelain gets used up after being exposed to bin contents for a time? as I'm sure there must be some protein (nitrogen stuff in the bin) for it to react with? (According to Wikipedia, the enzyme will last a week at room temperature.) There is absolutely no doubt about what bromelain does to protein (it dissolves collagen in flesh over time) and worms are high in protein thus any worms slithering through or consuming bromelain should slowly turn to mush some time after contacting it. Thinking about it, I guess if I were to feed fresh pineapple to my worms, I'd pop it into the microwave oven for a minute first, let it cool down and then feed... as heating will deactivate the enzyme.

Here is a little excerpt quoted from Wikipedia on annelids (all segmented worms including earthworms)...

"Their bodies are covered by a cuticle (outer covering) that does not contain cells but is secreted by cells in the skin underneath, is made of tough but flexible collagen and does not molt"... "Annelids' cuticles are made of collagen fibers, usually in layers that spiral in alternating directions so that the fibers cross each other. These are secreted by the one-cell deep epidermis (outermost skin layer). Under the epidermis is the dermis, which is made of connective tissue, in other words a combination of cells and non-cellular materials such as collagen"

Sounds like this is an experiment just waiting for someone carry it out... take say ten fat, healthy worms placed in a butter tub with just an inch or two of old castings for bedding, introduce a sizeable quantity of fresh pineapple spread across the surface, pop on the lid (with holes punched) and place it in a quiet, dark closet somewhere and then re-count the worms in a day or two later. As I said, I don't juice pineapple anymore. So ...thinking along the lines of Myth Busters (but without the explosions), it might be fun to do. Perhaps it'll have to be me... maybe in a few weeks.

I checked the bin a few minutes ago.....there is a mass of worms consuming it...it seems like most of it has already been consumed. Also there are many pot worms in the mix consuming what is left. Perhaps juicing along with blending deactivates the enzymes. I was expecting a negative reaction but the worms don't seem to care. This is not something i would not do often though...it was just an experiment.

So what you're saying is... this myth is BUSTED! Yeah, score one for the worms.

I dumped about 40 lbs of citrus scraps on part of my worm bed. 2 days later, the scraps are covered in worms even though there is plenty of citrus free real estate.

Did these "citrus scraps" include the rinds?

I am interested in the analysed affect of feeding citrus. Everyone who has tried it, please post the result by day and finally after about 1 week.

Yes

Is it possible that there are different reactions from the worms to different kind of citrus? Comparing oranges to lemons, I'd say that oranges are mild. Maybe the bigger the citrus fruit the milder it's ill effect to the worm bin? Or maybe as a barometer, if we cringe by the thought of it, so would the worms. Pomeloes will provide a lot of worm food, except for the outer skin.