My butterfly appears healthy

A questionable caterpillar or chrysalis emerges as a ‘healthy’ butterfly.


For some reason, if a caterpillar or chrysalis appears sickly yet the adult butterfly emerges, pumps it wings full, and is able to fly, we assume it is healthy. Why?

Seriously. Why?

That was a question I asked myself one day.

For some reason, although as a ‘child’ (caterpillar) and/or ‘teenager’ (chrysalis) a butterfly may show signs of problems, if it emerges as an adult and appears healthy, we want to claim that it is ‘totally healthy with no problems’.

We accept that other animals can have invisible diseases but automatically assume that if a caterpillar seems sickly yet emerges strong and looks normal, it IS healthy. Yes, it may be healthy. On the other hand, it may not be healthy. In humans, some diseases don’t show themselves in a way that we can ‘see’ or ‘tell’. Butterflies are the same way. Some are so badly diseased, appearing healthy, that the disease is passed along INSIDE the offspring, INSIDE the eggs.

Remember, nature must kill most butterflies before they become adults or butterflies would become extinct. (To read the numbers and find out why, click on this sentence.) Butterfly diseases run rampant in nature.

As butterfly breeders, we often send caterpillars to a pathology lab to be screened for disease pathogens before they show signs or symptoms of disease. We hold ourselves to high standards.

As enthusiasts, you don’t need to send caterpillars for screening. You simply need to use clean sanitary rearing procedures and be aware the disease in your rearing cage can be a serious issue for your caterpillars.

If you are raising caterpillars and are using clean sanitary conditions and rearing habitats, it is important that you destroy any caterpillar that you know is diseased. If it seems fine, release it!