Specific Diseases in Caterpillars, Chrysalises, and Adult Monarch Butterflies

What happened to my Monarch caterpillar? Is my Monarch chrysalis OK? Why did my Monarch caterpillar die? These and dozens more questions pour out of the hearts of people who treasure and raise Monarch caterpillars when disaster happens to one or more of them.

More people raise Monarch butterflies than any other species other than, perhaps, Painted Lady butterflies. Nature is determined to keep the balance level by only allowing 1 or 2 out of 100 eggs laid to become adult butterflies. Nature uses disease as one control measure.

Monarch butterfly with OE

Monarch Butterfly With OE
‘Dirty’ Abdomen

Monarch Butterfly Without OE Ophryocystis elektroscirrha

Monarch Butterfly Without OE
Ophryocystis elektroscirrha

A freshly emerged Monarch butterfly that has severe OE (Ophryocystis elektroscirrha)often has a smudged looking or dirty looking abdomen. The abdomen should have clear crisp white scales and black scales. If the abdomen is covered in spores, the white scales will not be pure white. Over 100 spores can fit on one scale. This is NOT a sure means to identify OE. To learn how to check an adult butterfly for OE, click on this sentence.

Monarch butterflies that are older or have been flying around may have knocked off some of the white scales, causing the same appearance as a Monarch butterfly that has OE.

Learn more about OE by clicking on this sentence.

Caterpillars with OE may or may not have black spots on their skin/cuticle. To most people, unless the OE infection is severe, the caterpillars appear and act normal.

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