I have a colony that has recently entered a steep decline. The hive was healthy until mid-September. Colony location is coastal California.
The most likely cause of the decline is a big increase in Varroa. The Varroa are treated with screened board, powdered sugar, and wintergreen treatments, the mites are reduced somewhat recently.
I have a significant number of "crawlers" that are missing antennas. Brown nubs (not mites) are observable where the root of the antenna would normally be located. I believe based on the the condition of the body hair, that these are recent hatches.
DWV bees are also seen, but fewer in number than the antenna-less crawlers.
A search of this forums doesn't pick up any hits for antenna-less condition being associated with parasitic mite syndrome.
Have others seen this antenna-less symptom, or does this imply some other colony insult/disease.