Proper noun
Brood X
One of 15 broods of periodical cicadas that appear regularly throughout the eastern United States.
“a 10-gallon batch of beer that includes smoked cicadas as an ingredient ” “The base beer is a barley wine and targeted it to 21 Plato (thus the final beer will be about 10.3% alcohol by volume) because the cicada Brood X will emerge again in 2021.” Source: Internet
It is a reference to the negative experience he had and it mentions the Brood X cicada infestation Princeton experienced that June 1970. Source: Internet