Information adapted from an original article by Edith Smith of Shady Oak Butterfly Farm,
NOTE: I do not routinely treat the leaves of the host plants I use with the Clorox solution described below, but if you suspect a plant is contaminated and you can’t access anything else, this method offers a solution. I currently do not need to do this because I have multiple plants to choose from and the chance of contamination is very low because I do not breed caterpillars outdoors.
METHODS TO DISINFECT
Contaminated equipment, including host plant leaves, pose a significant threat to caterpillars. As caterpillars feed, they may contract and spread a deadly disease known as Nuclear Polyhedrosis Virus or NPV. Wild butterflies and moths sometimes contaminate their food plants with NPV which is deadly to all Lepidoptera species. But what can we do if raising caterpillars indoors?
Simple! Disinfect equipment and even leaves with a bleach solution before changing the caterpillars.
Indoor Recipe for Disinfecting Leaves:
We are using 7.25 cups of water to 1/4 cup of regular Clorox bleach (sodium hypochlorite 7.5%) to disinfect leaves. Do not use splashless or other kinds of bleach with added ingredients. Stick with what has been shown to work through decades of experience by professional scientists and butterfly/moth breeders. FOR CLEANING EQUIPMENT, I USE THIS BLEACH MIXTURE IN A SPRAY BOTTLE SET TO “STREAM.” I AIM THE STREAM INTO A SINK OR TUB AND WEAR AN APRON TO PROTECT MY CLOTHES FROM BLEACH. I WAIT 5 MINUTES THEN RINSE THOROUGHLY WITH CLEAR WATER.
~ Plastic Gloves (preferably dishwashing gloves that reach the elbow)
~ Three containers large enough to hold the cut plant material
~ Plastic measuring cup and container
~ Bleach (I use regular Clorox bleach, where the sodium hypochlorite concentration is 7.5%)
~ Clean Water
~ Leaves or stems
~ Container with clear water to wash stems after leaves are decontaminated with Clorox solution. Let leaves dry or pat dry.
~ Airtight plastic bags to store disinfected leaves in refrigerator crisper.
- Measure the correct percentage of bleach and water in one container.
- Fill the second and third containers with clear water.
- Wearing gloves, insert the leaves/stems into the bleach solution.
- During the 5-minute bleach bath, agitate the leaves in the bleach solution gently every minute for 10 seconds for a full 5 minutes. Agitation is recommended because surface tension prevents the solution from touching all parts of the leaves.
- After 5 minutes, remove the leaves and place them in the clean water bath, again agitating every minute or so for a 3-minute total rinse.
- Dump the water, refill and agitate again over a 3 minute period.
- Remove the leaves from the water and pat excess water with clean paper towel to dry.
- Stand stem cuttings in a container with two or so inches of water in the bottom. If only individual leaves are disinfected, lay them out between dry paper towels or pat totally dry.
- After leaves have dried, they are ready to feed to caterpillars.
- If extra leaves were disinfected, they can be placed in sealed plastic bags in the refrigerator. It is possible to disinfect several days to weeks of leaves ahead, dry them completely, and then store the extra in the refrigerator in airtight ziplock bags. Treat it like lettuce and other vegetables we keep in the refrigerator, preferably in the crisper section.
DISINFECT CATERPILLAR EGGS USING THE SAME BLEACH SOLUTION BUT LEAVE EGGS IN SOLUTION FOR EXACTLY 60 SECONDS (NEVER MORE!) AND RINSE WITH CLEAR WATER.
(SEE BELOW FOR MORE ABOUT DISINFECTING EGGS.)
~ Leaves are not infected, they are contaminated. Pathogens are on the outside of the leaf. The plant is simply a surface that the pathogens rest upon.
~ Contaminated leaves look like any other leaf in appearance. The pathogens are too small to see without a microscope. Some pathogens must have a strong microscope and the leaf treated with oil immersion for the pathogens to be visible.
~Always wear gloves when using your bleach solution. An apron is a good idea too. If you splash bleach solution on colored clothes, bleached white spots could be the result!
~ Gloves also protect rings. The bleach solution will dissolve the cement holding ring stones!
Also, refer to their excellent video on how to Disinfect Monarch Butterfly Eggs with Bleach (same applies to all Lepidoptera species):