Six Steps to Keep Caterpillars Healthy and Free from Disease

Caterpillars of certain butterfly species are easier to raise than others.  In addition to OE that can infect monarch caterpillars, other butterfly caterpillars can get sick and die from viruses or bacteria as a result of many factors.  The following helpful hints can help you maintain a safe environment for raising butterfly caterpillars through to healthy adult butterflies.

1. Raise caterpillars in manageable quantities.  Unless you are an experienced butterfly rearer or breeder, rearing caterpillars in mass quantities greatly increases the chance for larval disease.  
2. Remove caterpillar frass regularly.  Whether rearing caterpillars in an open terrarium, it is always advisable to create a regular regimen of removing caterpillar frass as regularly as possible.  The longer caterpillars are exposed to their own frass, the more likely caterpillars can get sick.
3. Keep Rearing Environment Free from Humidity.  Pathogens can multiply exponentially and easily infect caterpillars if caterpillar frass is allowed to remain moist.  With the exception of admirals or viceroys, raise caterpillars in an environment with plenty of airflow; allowing frass to dry naturally.
4. Raise caterpillars on potted plants as opposed to cuttings when possible.   Raising caterpillars on potted plants has advantages over cuttings because of the nutritional value of live plants.  If you do use host plant cuttings, replace regularly, depending upon the species of butterfly and variety of host plant.  Do NOT allow cuttings to deteriorate or rot.  More.
5. Disinfect your rearing environment regularly.  When dealing with the disinfection of viruses or bacteria, using a two chain quaternary ammonium compound aerosol (like Lysol) is the easiest method to disinfect 99.9 percent of viruses and bacteria.  Apply aerosol directly on non-porous containers and cages for 30 seconds and remove with clean paper towel.  Using bleach (Sodium hypochlorite) also is effective; but can be more labor intensive for some.  Chemical disinfectants are used for preventative measures and cannot heal caterpillars once they are infected.
6. Understand which butterfly taxonomic groups are more susceptible to disease and require more attention:  Some species, species groups, or genera require more attention than others.  Use the following matrix as a general guideline:

Taxonomic Group:	Disease Susceptibility:	Special Concerns:
Nymphalidae:  Nymphalinae and Melitaeinae (brushfoot butterflies including anglewings, tortoiseshells, ladies, buckeyes, checkerspots, and crescent spots.)	Low	Use open terrarium technique. Disinfect, replace cuttings, and remove frass every five days.
Nymphalidae:  Danainae (monarchs and queens) and Heliconiinae (longwings)	Medium	Disinfect for OE; remove frass and replace cuttings every three or four days.
Nymphalidae: Limenitidinae (admirals and viceroys)	Low	Larvae are less susceptible to disease when rearing in a humid environment as they are accustomed to this in nature.
Nymphalidae: Satyrinae (wood nymphs and ringlets only )	Low	Larvae are generalists and avoid disease if reared in potted grasses of many common varieties
Nymphalidae:  Greater Fritillaries from the genus, Speyeria.	High	Special needs group.  See instructions located here.
Pieridae and Lycaenidae (white/sulphurs/orange tips and blues/coppers/hairstreaks)	Medium/High	Avoid closed container rearing whenever possible. Larvae are very susceptible to illness when overexposed to their own moist frass; even if reared in isolation.
Papilionidae (Tiger and machaon group swallowtails)	Medium	Avoid closed container rearing whenever possible.  Avoid humidity; especially for Western North American species.
Papilionidae:  Papilio indra complex	High	Special needs group.  See instructions located here.

This matrix is a general summary and is not all-inclusive.  For more information about species-specific rearing strategies, please see http://www.raisingbutterflies.org/raising_butterflies_301/ or email me.