Newsletter for September 2020

Backyard Butterflies

We're Crazy for Caterpillars!

Collection of Caterpillars

“The caterpillar does all the work,

but the butterfly gets all the publicity.”

― George Carlin

Fellow Butterfliers,

I hope this finds you in good spirits and health as we make our way into autumn. It paradoxically feels like it was just yesterday and a lifetime ago that it was becoming spring.

September is a busy time of year as all butterflies are preparing for winter by either laying eggs for the last brood of the year or getting ready to migrate. I call this time of year "the last hurrah" for caterpillars. Compared to this spring, I now have an abundance of cats to feed. This week the habitat is finally being put to use by Pipevine, Spicebush, and Black Swallowtails, Monarchs, and Snowberry Clearwing Hummingbird moth caterpillars. I assume that there is a sizeable Sleepy Orange population about to defoliate every self-sown sicklepod by the end of October.

This month I'd like to share with you some of my wit and wisdom I've gained over the years since I raised my first little brood of Monarchs back in September 2012. My experiences were very positive and successful in the beginning, yet as I continued into my second and third years I began experiencing what I call the "hidden side" to raising caterpillars: parasitization, infection, and pesticide poisoning from store bought parsley not realizing it had been treated. While there are many resources on Google ranging from websites and Facebook groups, I had often wished that there was a physical class or workshop available to help guide me.

Due to Covid-19 safely conducting my traditional September Raise a Caterpillar Workshops has required some adaptation. I think that by holding it outside, following guidelines, and limiting participant size, it will be a relatively low risk activity. I look forward to you joining me on the 12th!

I'm also using this newsletter as a mini workshop to provide you with some guidance in case you don't feel comfortable attending in person, which is why it's so long and a bit delayed. I'm always available to help you raise caterpillars outside of attending a workshop as well.

Peace, Love & Caterpillars,

Caring for Caterpillars

I got started hand raising caterpillars by happy accident. Someone gave us milkweeds and when I found caterpillars I felt compelled to raise them. I saw them as helpless, vulnerable and fragile. I wanted to care for them even though I honestly didn't know how.

Fast forward to now and my approach to raising caterpillars has changed as my understanding about these remarkable critters has grown. While caterpillars are vulnerable and fragile they aren't as helpless as I thought. They can carry out their life cycle without my help. I've come to understand the role caterpillars have in the food chain and the role parasites and disease have as well. I think it's important to have a philosophy when hand raising caterpillars as it will govern what you will and won't do in administering your care for them.

May the Odds Be Ever in Your Favor

Keep in mind that by design not every egg laid becomes a butterfly. It's estimated that only 2% of all eggs laid in the wild become an adult. At each stage of the life cycle, a butterfly makes for a tasty meal for someone. Caterpillars and chrysalises are also subject to infectious diseases, predation, parasitization, weather, and human activities such as use of pesticides and loss of habitat.

Hand raising helps increase their chances of becoming a healthy butterfly, but even when using good rearing techniques there will still be losses–just not as many.

It's up to you to decide at what stage of the life cycle you want to begin raising the butterfly. Some people will collect eggs to minimize parasitization of the caterpillar after it hatches. For some species, raising from an egg can be challenging. I've not had much luck with raising from eggs. My preference is to let them raise themselves for awhile before supporting them with hand raising. As a result of my choice I raise a few parasitized caterpillars–this is not a bad thing–it is part of nature.
Silver Spotted Skipper egg on false indigo
Silver Spotted Skipper egg on false indigo

Winter Strategy

All butterfly species have what I call a "winter strategy", meaning: In what stage of the life cycle do they spend the winter months? It's important to know what their respective strategy is so you can provide the right kind of care.

The Swallowtails spend the winter as a chrysalis. The Monarch spends it as an adult and migrates to a different climate, while other species remain as adults without migrating. Some species spend the winter as a caterpillar inside of a hibernaculum, and some will exist as an egg.

Equipment for Rearing Caterpillars

Equipment for raising caterpillars need not be fancy or expensive. I prefer to use plastic critter keepers, while others may use glass aquariums or terrariums, and others prefer fabric pop-up enclosures that are similar to a collapsible laundry hamper. Some build unique rearing enclosures that resemble a wardrobe or small screened porch.

It's important to give caterpillars adequate space to grow. Some species will become cannibalistic if crowded together. Big caterpillars that walk over chrysalises in the rearing container can puncture the fragile cuticle of the chrysalis. Swallowtails will pupate on other chrysalises, essentially trapping their sibling inside with their silk pad.

I use small plastic sauce cups with lids to keep the host plant hydrated. Some prefer to use florist tubes. I poke some holes in the lid and fill the cup with water. This does a good job for the majority of host plants. I usually don't have to keep milkweed leaves hydrated because they are eaten so quickly.

A low temp glue gun and small wooden dowels can be useful to have on hand if a chrysalis needs to be relocated.
American Lady chrysalises
American Lady chrysalises glued to a stick

Good Rearing Practices

  • Clean out frass daily from rearing containers and enclosures
  • Constant supply of fresh, pesticide free host plant, free of other insects, and washed if necessary
  • Sanitize containers between broods
  • If possible/practical collect eggs to raise
  • Keep rearing containers outside in a protect location such as a porch, screened porch, balcony, etc. so that caterpillars experience ambient temperatures and photoperiods
  • Don't over-crowd caterpillars in containers
  • Separate chrysalises from caterpillars so butterflies eclose in their own container
  • Never use pesticides near caterpillars, including flea and tick treatments for pets

Nectar Plants

Providing host plants is one part of encouraging eggs to be laid in your garden or habitat. Creating a desirable territory for butterflies to raise their young is accomplished by planting a variety of nectar plants. Butterfly season begins as early as February and continues through to the end of October. Having multi-season nectar sources is ideal.

Host Plants

What is really nifty about raising butterflies is that you can select what species you want to raise by planting their host plants. It's not an exaggeration to say: If you plant it, they will come. The challenging part is waiting for them to find and use your host plants. We're still waiting for an adventurous Zebra Swallowtail to find our paw paw trees. It's been over seven years and counting.

The first rule of raising any caterpillar is this: You can never over feed a caterpillar. All of the nutrients and moisture they need are gotten from eating the leaves and sometimes the flowers and seeds of their host plant. A caterpillar that has plentiful access to its host plant will reach maximum size and be ready to take on the world. A study found that Monarch caterpillars will be smaller in size if they go 24 hrs without food.

The second rule is: Always over-estimate how much host plant you will need to raise a caterpillar. Some species of caterpillar are voracious eaters, such as Monarchs, Black Swallowtails, Pipevine Swallowtails, and Sleepy Oranges.

During this time of year host plants are often not in the best condition because of heat and drought. It can be a challenge to have sufficient host plant to feed the end of the year broods. This is why we created our Caterpillar Support Program.


Many people want to help support the declining Monarch population. In addition to planting their host plants, members of the genus Asclepias or Milkweed Family, some want to provide further support by hand raising caterpillars to help increase their odds of survival.

Raising Monarchs presents some unique challenges compared to raising other species. In hot weather they are fast growing and will consume large amounts of host plants, typically causing depletion of their host plant much to the panic of the gardener who planted milkweed with good intentions. Monarch caterpillars are susceptible to a parasitic protozoan infection called Ophryocystis elektroscirrha (OE) that other species are not infected by.
August 25 Pilot Mtn NABA (25 of 38)
Monarch caterpillar in the wild at Pilot Mtn SP

FAQs About Raising Monarchs

When should I stop bringing in caterpillars to raise?
I'm always a bit befuddled by this question when it invariably comes up in Facebook groups in September. My answer is: When you stop finding caterpillars to bring in to raise.

The Monarch will naturally stop laying eggs in response to environmental cues, such as hours of daylight and temperature. The migrating generation will not mate or lay eggs because they are not sexually mature. They only become so after winter.

I have Monarch caterpillars/chrysalises and there is a frost warning. What do I do?
Bring them inside for the night to protect them and then return them back outside once the temperature has warmed up above freezing.

Does using non-native milkweed keep Monarchs from migrating?
Just like with feeding wild birds, no it doesn't keep them from migrating.

A what outside temperature can I release butterflies?
As long as it is above freezing you can release them outside. However, it needs to be around 60-65°F for them to be able to fly.

I have Monarchs eclosing and there's no more flowers in my yard/area. What do I do?
Go ahead and release them when they eclose if it's not raining and it is warm enough. They will fly to find nectar sources.

What is the most humane way to euthanize a caterpillar, chrysalis, or butterfly?
Place them in the freezer.

Black Swallowtails

Raising an Eastern Black Swallowtail, is fairly easy and successful to do, which is why it's the star of the Raise a Caterpillar Workshop. The knowledge and skills you'll gain from the workshop are applicable to other species if you decide to hand raise them.

Many of the host plants the Black Swallowtail uses, members of the Wild Carrot Family, are simple to cultivate and readily available. Out of all of the Swallowtails the Black Swallowtail is the least seen as an adult and yet we know they exists because of the many caterpillars people find on their parsley, dill, and fennel plants.
april 28 (2 of 24)
Black Swallowtail caterpillars have a Resting Sad Face appearance
Female Black Swallowtail from this spring
She had spent the winter as a chrysalis

FAQs About Raising Black Swallowtails

Is this a Black Swallowtail egg on my parsley/fennel? (Photo attached)
Sometimes the photo is of a leaf-footed bug egg, sometimes the photo is of a Swallowtail egg.

A Black Swallowtail egg is yellow-ish white in color, and is perfectly round. They are laid singularly but the female may lay other eggs near one another.

Leaf-footed bug eggs are football shaped, quite large, and have a pearlescent sheen.
april 9 (7 of 9)
Black Swallowtail egg
Can I feed caterpillars parsley, dill, or fennel bought at a grocery store? Bought at a nursery?
It's a good idea to assume that produce bought at a grocery store or a big box nursery store has been treated with pesticides because it's meant for human consumption. This applies to organic produce as well.

There are locally owned nurseries that sell untreated plants. Talk with the owners to find out their practices and to learn if they understand about host plants.

I followed the good rearing practices and my caterpillar/chrysalis died. Did I do something wrong?
No. You can do everything right and still have caterpillars and chrysalises die.

A butterfly eclosed from my hibernating chrysalises that I have kept outside and it's the middle of winter. What do I do?
Brief spells of warm weather in December, January, or February can trigger a butterfly to come out of hibernation before flowers are in bloom. If this happens there are a few options: You can keep it captive and feed it Gatorade or a sugar solution. It's life expectancy is just a few weeks. You can release it and hope for the best. If you know ahead of time you can temporarily store your chrysalises in the fridge and then return them to the outside once the warm spell has ended.

Milkweed Bugs

I'm often asked to identify the different insects people see on their milkweed plants. The primary concern is: Will these insects harm Monarch caterpillars? The answer is: No, these insects won't hurt caterpillars. Sometimes I'm asked if these bugs are bad for the plant. My answer is: Not exactly.
While these bugs feed on the plant by either eating the leaves or sucking out the juices, milkweed plants have co-evolved to be used in this way by these insects. There is no need to remove these bugs from your milkweed as they are part of the greater milkweed ecosystem.
My logic is, would you go out in the wild and remove these bugs? Probably not. Then why remove them from the milkweeds growing in your yard?

Besides, I don't think it's possible to keep the Oleander aphids off the plants as they are numerous and rapidly breed. Also, if you have dozens to hundreds of plants it's just not practical to spend time removing any of these bugs. Lastly, all insects need our support, not just Monarchs.
Large Milkweed Bug

Large Milkweed Bug

Oncopeltus fasciatus. Rock Creek Park, Washington, DC, USA by Katja Schulz is licensed under CC BY 2.0
Small Milkweed Bug

Small Milkweed Bug

Copyright © 2004 Troy Bartlett licensed under CC BY-ND-NC 1.0
Swamp Milkweed Beetle

Swamp Milkweed Leaf Beetle

Copyright © 2006 tom murray CC BY-ND-NC 1.0
Red Milkweed Beetles

Red Milkweed Beetle

Oleander Aphids

Oleander Aphids

Milkweed Tussock moth caterpillars

Milkweed Tussock moth caterpillars

Raise a Caterpillar Workshop

Saturday, September 12, 2020

Session 1 – 10:00 AM to 11:00 AM • Session 2 – 1:00 PM to 2:00 PM
Caring for caterpillars by hand raising them is a magical process to witness that never gets old.

We offer our Raise a Caterpillar Workshop for all ages to help you get started with hand raising Black Swallowtail caterpillars. This is a very easy species to care for successfully when you follow good rearing practices. All ages are welcome to attend. For more information click the button below.

Workshop size is limited to 5 registrations per time slot. Each registration is for one adult and up to two children.
Aug6 (31 of 32)

Caterpillar Support

We offer Caterpillar Support to those who are in need of host plants, foster care, or adoption of caterpillars.

There are 18 species of caterpillar that we can provide the host plant for, and we can also provide host plants for some species of moths.

This program is free of charge. All you need to do is apply letting us know what host plants you need, or if you need us to foster care or adopt your caterpillars.

Common Buckeye late instar
Common Buckeye
Caterpillars in the photo collage, Row 1 (l to r): Pipevine Swallowtail, American Lady. Row 2: Eastern Black Swallowtail, Spicebush Swallowtail. Row 3: Question Mark, Snowberry Clearwing Hummingbird moth.

Plant Pots Return Request

We appreciate the return of pots for re-use if you happen to be passing by our way. No need to contact us, just drop them off on our porch.
transparentBYBF-1 (1)

Coming Up in October:

Getting Read to Hibernate!