What do infected monarchs look like?

The answer to this question depends on how heavily infected the monarch is. Many OE infections, especially of eastern North American monarchs, are 'mild' cases, and the infected adult monarch will look nearly identical to a healthy adult. Mildly infected adults will also act normal, so it is usually impossible to know if they are infected without testing them using the methods described below. Unfortunately for those of us that rear monarchs in captivity, these mildly infected adults can spread their spores around their cages and rearing containers just as well as heavily infected ones, which is why it is essential to test all adult monarchs upon eclosion, and remove any infected ones immediately. Also, since there is no way to 'cure' adult monarchs once infected, they must be destroyed. Releasing them to the wild will only spread the parasites further and you will risk contaminating your favorite local milkweed patch.

Below are some pictures of various OE infected monarchs. The monarch in the bottom right image is indeed infected, but appears otherwise normal.


If you are interested in examining your own butterflies for the OE parasite, you can follow these steps using the supplies sent to you in your new kit. Most of our participants use the swab method below for project MonarchHealth.

Things you will need for testing using the tape method:

Disposable gloves
Clear tape stickers
Blank index cards


Step 1. Put on your gloves!

Step 2. Hold the monarch firmly as shown in the picture below, using a gloved hand.  Be sure not to use your other hand to touch the butterfly because that hand will be used to hold the tape sticker and sample for spores.  It is critical that you keep your bare hand completely free of touching the butterfly throughout this process!


Step 3. Pick up a tape sticker using your other hand and gently place the sticky side of the piece of tape to the abdomen of the monarch. Press down so that it wraps around and sticks to the sides of the abdomen.


Step 4. Gently peel the tape sticker off and stick it to the index card. You will remove some scales in the process, but don't worry, it will not harm the monarch.


Finish by labeling the tape sample on the spore card with the identity (we use a number) of the monarch. Continue these steps until you have sampled all of your monarchs. In the end, your index cards should look something like this:

The numbers on the bottom of each sample refer to the number of the butterfly in our lab, and the numbers above refer to the parasite 'spore load' on each monarch (we use a 0-5 scaling system). Notice that one monarch from these samples was infected and was given a 5 score (heaviest infection category).

Are the monarchs I sampled infected?

We will examine if your samples show if the monarchs are infected. Once we have the results, we will notify you the infection status. Results from all participants will be compiled and sent to all volunteers and updated on the website.

Here's what a sample looks like when we examine it under the microscope:

The red arrows indicate the parasite spores in this image. The big objects are the monarch scales. The spores look like tiny lemon-shaped objects, often clumped together. They often have a reddish tinge. This monarch would be considered heavily infected.

Have a question? Go to our Frequently Asked Questions section.