Alfalfa Butterfly: All You Need to Know

The Alfalfa Butterfly is a fascinating creature that plays a crucial role in the ecosystem. Known for its vibrant colors and elegant flight, these butterflies are not only beautiful to observe but also essential for pollination.

Alfalfa Butterflies (Colias eurytheme) exhibit a unique phenomenon โ€“ a two-way migration similar to birds, making them the only known butterfly species to do so.

During their migration, they assist in the pollination of various plants, including their namesake, alfalfa. This process is vital for the health and sustainability of our environment.

Female Alfalfa Butterfly

Alfalfa Butterfly Basics


The Alfalfa Butterfly, also known as the Orange Sulphur butterfly, has a wingspan of 1.5 to 2.5 inches. It displays different colors according to its gender:

  • Males: Bright orange-yellow with a dark border
  • Females: Pale yellow with pale spots within the dark border

Life Cycle

The life cycle of the Alfalfa Butterfly comprises four stages:

  1. Egg: Small, yellow-green eggs laid on alfalfa leaves
  2. Larva: Green, black-spotted caterpillars appear velvety due to many fine hairs covering the entire body. They munch on alfalfa leaves
  3. Pupa: Green or yellow chrysalis, hanging from alfalfa leaves
  4. Adult: Mature butterfly

Distribution and Habitat

Alfalfa Butterflies are found across the United States, primarily in:

  • Agricultural fields
  • Roadsides
  • Urban gardens

As the name suggests, they are most commonly associated with alfalfa fields, as their larvae feed on alfalfa leaves.

Importance of Alfalfa Butterflies

Role in Alfalfa Fields

Alfalfa butterflies play a vital role in alfalfa fields as pollinators. They enhance the reproduction process by transferring pollen between plants. Some examples of their importance in alfalfa fields include:

  • Increasing alfalfa yield
  • Improving seed quality

Their Impact on Ecosystems

Alfalfa butterflies not only affect alfalfa fields but also have a broader impact on ecosystems. These butterflies serve as a food source for various predators, like birds and spiders.

By attracting these predators to alfalfa fields, they contribute to pest control by keeping some harmful insects in check. Furthermore, their presence indicates a robust and diverse ecosystem, benefiting plant life and agriculture overall.

The impacts of alfalfa butterflies on ecosystems can be summarized as follows:

  • Pollination of other plants in the ecosystem
  • Food source for predators, contributing to natural pest control
  • Indicator species signaling a healthy ecosystem

Alfalfa Butterfly

Caring for Alfalfa Butterflies

Attracting Alfalfa Butterflies

Alfalfa butterflies are drawn to their main food source: alfalfa plants. To attract them, consider:

  • Planting alfalfa in your garden
  • Including flowering plants that provide nectar

These butterflies thrive in sunny areas, so ensure ample sunlight in the area where alfalfa is grown.

Protecting Their Habitats

It’s essential to preserve alfalfa butterfly habitats to support their population. Keep the following in mind:

  • Practice responsible pest management
  • Limit the use of pesticides
  • Provide water sources

By offering alfalfa butterflies a safe and healthy habitat, their population will flourish in your area.

This image has an empty alt attribute; its file name is alfalfa_sulfurs_hellywell_2-300x225.jpg

Potential Challenges

Pest Control and Management

Alfalfa is susceptible to different pests, one of the most common being the alfalfa weevil. Managing these pests can be challenging, especially due to concerns about insecticide resistance.

Here are some characteristics of the alfalfa weevil:

  • Larvae and adults cause defoliation, reducing yield and quality
  • Management includes scouting, threshold-based treatments, and conservation of natural enemies

Pros of pest control methods:

  • Timely scouting and treatment can save yields
  • Integrated Pest Management (IPM) strategies minimize environmental impact

Cons of pest control methods:

  • Insecticides may harm beneficial insects
  • Resistance can develop, reducing the effectiveness of treatments

Climate Change and Its Effects

Climate change may affect alfalfa plants in various ways, such as shifting pest populations and altering patterns of diseases. Some potential consequences of climate change on alfalfa include:

  • Increased vulnerability to drought and heat stress
  • Altered growth cycles due to temperature fluctuations
  • Shifts in pest and disease ranges, impacting both management strategies and crop production

Adapting to these challenges will require careful monitoring, updated management practices, and potentially exploring alternative crop varieties that may be better suited to changing climate conditions.


The Alfalfa Butterfly is a beautiful creature in the ecosystem. It is unique for its two two-way migration cycle. Apart from that, these butterflies play a crucial role in pollination, particularly in alfalfa fields.

By understanding their habitat, caring for them, and addressing potential challenges, we can ensure their preservation and create a good population of these remarkable butterflies.

Readers’ Mail

Over the years, has received hundreds of letters and some beautiful images asking us about Alfalfa Butterflies and Alfalfa Webworm Moths. Scroll down to have a look at some of them.

Letter 1 – Snout Moth is Alfalfa Webworm Moth

Subject: Pretty moth on my walk
Location: Longmont, CO (Near Boulder)
June 30, 2016, 3:50 pm
Hello friend,
Thanks for always doing such a great job with this site. I follow you on Facebook avidly. ๐Ÿ™‚

I saw this critter on my walk to work and was so intrigued by the “eyes” near its antennae and the beautiful pattern on its wings that I stopped and took a photo so I could send it to you.

Thanks for any information you can share. ๐Ÿ™‚
Signature: Claire, who loves moths

Snout Moth
Alfalfa Webworm Moth

Dear Claire,
This is one of the Snout Moths in the family Pyralidae, which according to BugGuide has “681 species in our area” in North America, or Crambidae, which according to BugGuide has “861 species in 10 subfamilies in our area.” 

Many species in the families look quite similar, though the markings on your individual are quite distinctive, though subtle. 

We will continue to browse through BugGuide and the Moth Photographers Group in an attempt to identify your species. 

We now believe this is the Alfalfa Webworm, Loxostege cereralis, based on images posted to BugGuide where it states:  “larvae feed on alfalfa and a variety of other crops and weed species.”

As always, thank you so much for your hard work! It is always really cool to know more about the area and the plants/animals that live in it!

I have seen many more of these since I sent it to you, it must be the right time of year for them to thrive.

Letter 2 – Alfalfa Sulfurs Courting

Bug Love โ€“ Sulphur Butterflies
Location: New Canaan, CT
October 10, 2011, 8:51 pm
Saw a large group of these Alfalfa Sulphur Butterflies on Zinias at the New Canaan CT Nature Center. There was a lot of mating going on.

The male has solid brown rims around the edges of his wings and the female has spots in her brown wing edges. Arenโ€™t they beautiful?! These and Cabbage Whites are the only butterflies I have seen for the last 2 weeks.

I think the weather has shooed all the others away.

Signature: Hellywell

Alfalfa Sulfurs

Dear Hellywell,
Your photos of frolicking and courting Alfalfa Sulfurs or Orange Sulfurs,
Colias eurytheme, are positively charming. 

Our editorial staff has fond memories of the Sulfurs flitting around the clover in the fields in Ohio, a sight that is sadly nonexistent in Los Angeles. 

Alfalfa Sulfurs

Mom in Ohio claims that zinnias are the best garden flowers for attracting butterflies.

Alfalfa Sulfurs

Letter 3 – Alfalfa Butterfly

Subject: Possible Orange Sulphur Butterfly
Location: Coryell County, Texas
February 17, 2014 10:00 pm
Hello, I hope you’re both well.

I think this is a Sulphur Butterfly, possibly an Orange Sulphur.

You kindly identified one for me last year; I’m noticing that the same butterfly species that visited a year ago have returned to the same patch of wildflowers this winter.

Many of the honeybees and butterflies seem to have very worn wings at this time. I’m guessing that this might be from the unusually cold, icy, and very windy weather that has occurred this winter.

So glad for the spring-like weather this week!
Signature: Ellen

Alfalfa Butterfly
Alfalfa Butterfly

Hi Ellen,
We agree that this is an Orange Sulphur,
Colias eurytheme, and we grew up calling it an Alfalfa Butterfly.  BugGuide also indicates the common name Alfalfa Sulphur.  The spotted border of the upper wings indicates that this is a female.  The male has a solid black border.

Alfalfa Butterfly
Alfalfa Butterfly

Letter 4 – Alfalfa Butterfly

Subject: butterfly
Location: Maryland
August 17, 2015 4:19 am
Saw this butterfly on our farm on the Eastern shore of Maryland on the Maryland-Delaware line towards Dover Delaware. I didn’t get a good look at the top side of the wings but think they were mostly yellow.

I have a good shot of the underside but I seem to be finding sites using different names for what this appears to be. Would love to have your take on it.
Signature: Patti Cooper

Female Alfalfa Butterfly
Female Alfalfa Butterfly

Dear Patti,
Your digital file was named “Southern Dogface” and we disagree with that identification, though the family is correct. 

Though you don’t have a dorsal view, it is possible to make out the markings through the wings, and we can see a row of lighter spots in the black border of the upper wing. 

It also appears that the coloration is slightly orange, indicating this is a female Alfalfa Butterfly or Orange Sulphur, Colias eurytheme.  You can compare your image to this BugGuide image.


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

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