29 Apr Why Are My Monarchs Turning Black and Dying?
Why Are My Monarchs Turning Black and Dying?
A certain percentage of monarch caterpillars and chrysalides just don’t make it into
adulthood and become butterflies. In fact, in nature without our intervention raising
monarchs, 90% of eggs laid fail to become monarch butterflies.
Caterpillars are vulnerable to a fair number of viruses, bacteria, parasites and predators.
When we have caterpillars die rather than thrive, it is always a bit of heartbreak as so many
of us get very attached to our dear caterpillars and monarch butterflies. We can help
caterpillars survive by learning about these issues and do what is necessary to maintain
clean, healthy milkweed and virus/parasite/bacteria free habitats. One thing that is
necessary is to clean frass (caterpillar poop) out of habitats daily. Another is to sanitize
habitats in between raising every batch of caterpillars. (Read about habitat cleaning
under Bleaching blog entry.)
“Black Death” is when a caterpillar looks healthy one day and then the next it gets
lethargic, then darkens and its body deflates and turns to mush, or what looks like
a healthy chrysalis turns dark and mushy. In most cases, black death is caused by
either a bacterium in the genus Pseudomonas or by the Nuclear polyhedrosis virus.
Read how all about it and how to help prevent NPV in your monarch garden: