Why Does This Monarch Butterfly Have Crumpled Wings?

How to Recognize OE Parasites in Monarch Butterflies

A monarch with deformed wings may be infected with parasites.
A monarch with deformed wings may be infected with parasites.

Debbie Hadley / WILD Jersey

Recent reports about the decline of monarch butterflies in North America have stirred the nature-loving public to take action in the hope of reversing the trend. Many people have planted backyard milkweed patches or installed butterfly gardens, and started paying closer attention to the monarchs that visit their yards. If you've taken the time to observe the monarch butterflies in your area, you've probably discovered that many monarchs don't make it to adulthood. Some will make it all the way through the pupal stage, only to emerge as deformed adults with crumpled wings, and unable to fly. Why are some monarch butterflies deformed like this?

Why Do Some Monarch Butterflies Have Crumpled Wings?

A protozoan parasite known as Ophryocystis elektroscirrha (OE) is most likely to blame when you find a monarch butterfly with crumpled wings. These single-celled organisms are obligate parasites, meaning they require a host organism in which to live and reproduce. Ophryocystis elektroscirrha is a parasite of monarch and queen butterflies and was first discovered in butterflies in Florida in the 1960's. Scientists have since confirmed that OE affects monarch butterflies worldwide, and is believed to have co-evolved with monarch and queen butterflies.

Monarch butterflies with high levels of OE infection may be too weak to emerge from the chrysalis completely and sometimes die during emergence. Those that do manage to break free of the pupal case may be too weak to hold on long enough to expand and dry their wings. An OE-infected adult may fall to the ground before its wings are fully open. The wings dry in the wrinkled and folded position, and the butterfly is unable to fly.

These deformed butterflies will not live long, unfortunately, and cannot be saved. If you find one on the ground and want to help it, you can place it in a protected area and give it some nectar-rich flowers or a sugar-water solution. There is nothing you can do to fix its wings, however, and it will be vulnerable to predators since it cannot fly.

What Are the Symptoms of Ophryocystis elektroscirrha (OE) Infection?

Monarch butterflies with low OE parasite loads may not show any symptoms of infection. But individuals with high parasite loads may exhibit any of the following symptoms:

Infected Pupa

  • Dark spots become visible a few days before the adult is expected to emerge
  • Unusual, asymmetrical coloration of the adult butterfly while still within the pupal case

Infected Adult Butterfly

  • Weakness
  • Difficulty emerging from the chrysalis
  • Failure to emerge from the chrysalis
  • Failure to cling to the chrysalis upon emergence
  • Crumpled or wrinkled wings that are not fully expanded

Although monarchs with low parasite loads may appear healthy, be able to fly, and reproduce successfully, they may still be affected by the parasites. OE-infected monarchs are often smaller, have shorter forewings, and weigh less than healthy, parasite-free monarchs. They are weaker fliers and are prone to desiccation. Male monarch butterflies infected with OE are less likely to mate.

How to Test a Butterfly for OE Infection

According to researchers at the University of Georgia, OE infection rates vary between the different monarch butterfly populations in North America. Non-migratory monarchs in southern Florida have the highest OE parasite infection rates, with 70% of that population carrying OE. About 30% of western migratory monarchs (those living west of the Rocky Mountains) are infected with OE. Eastern migratory monarchs have the lowest infection rate.

Infected butterflies do not always exhibit obvious symptoms of OE, but you can test a butterfly for OE infection quite easily. Infected monarch adults have OE spores (dormant cells) on the outside of their bodies, particularly on their abdomens. Scientists sample OE parasite loads by pressing clear Scotch tape on a butterfly's abdomen to pick up the OE spores. OE spores are visible—they look like tiny footballs—under magnification as low as 40x.

To test a butterfly for OE infection, simply press a piece of ultraclear Scotch tape against the butterfly's abdomen. Examine the tape under a microscope, and count the number of spores in a 1 cm by 1 cm area.

Once a butterfly is infected with OE, there is no way to treat the infection.