I had a customer that had a weak colony stop by with some frames that she thought looked suspect of a brood disease.
We looked them over. No discernible odor, no shrunken cappings, some perforated cappings, some dying brood. All the brood that was dying was older larvae. We tried a ropiness test but I could not find any dying brood in the milk chocolate color stage of decay. The ropiness test should be done on these larvae. Puncture the larvae with a toothpick. If it is American Foul Brood (AFB) it should rope out more than 1 inch from the larvae. I didn't see anything like that. I did see two dead larvae that had died with there tongues sticking up. This is an AFB clue.
There were some larvae that died in a hard white state. This is Chalkbrood a fungus. No cure for this, it usually goes away.
But back to the AFB. We took the frame into my shop and used the black light to look for AFB scale. AFB scale is a dead larvae that has died and dessicated to the bottom of a cell and formed a hard scale. AFB scale is highly contagious and can only be removed only with high temperature therapy, burn it. Removing the scale is a must or the colony will get reinfected after a regimen of antibiotics is over. AFB scale glows green when a black light is shined on to it.
AFB scale is always on the bottom of the cells. When looking for it, have the frame with the top bar at your chest and leaned slightly back. Shine the light so it hits the bottom of the cells.
So we took the frame and hit it with the black light. There were four cells of AFB scale on each side of the frames. They were glowing green and stood out from the other cells.
This beekeeper with a few clues, reacted to question of the health of her colonies. She had a weak colony with some discolored larvae and got advice because she was unsure and never had it before. She not only caught the AFB in a very early stage, but protected her other colonies from hopefully falling victim to this brood disease. She is going to burn the infected frames and treat the colony with Terramyacin. The Chalkbrood should clear up as the population increases.
She will keep an eye on all the colonies now to make sure they stay healthy.