Butterfly SZN

We need a rating system for the graffiti: more points if they use more than one color, and the letters need to be filled in. I don’t want to see any hollow letters.


Surprisingly, time marches on. That may be a personal problem. This post should be a treat for you faithful readers. As the title suggests, it’s going to be all about butterflies (and maybe me). I’ve gotten to work with two butterfly species this year, so hopefully you’ll get to vicariously live out my experience through this post. I think I have more words to say than usual, but they might be interesting. Besides, I’ll try to keep you distracted with pictures.

Mission Blue Butterfly

The first of our two species of concern is the Mission Blue Butterfly (MBB), Icaricia icarioides missionensis. The MBB is federally endangered and only found in the San Francisco Bay area. Adults are about the size of a quarter, and as you can see from the picture and the name, they’re blue (females have some brown in their blue). While the butterfly is beautiful, this insect only lives that way for about 10 days; the rest of its year-long life cycle is spent in larval stages and as a caterpillar. No matter the stage of life, however, they will always be found on and around lupine plants (the same genus as Texas bluebonnets). The MBB specializes on three species of low-growing lupines; they lay eggs on lupine leaves, newly hatched larvae feed on the same leaves, and larvae hibernate on the ground at the base of the lupine before emerging and feasting in preparation to transform into a butterfly and renew the cycle.

Challenges leading to the decline of the MBB are habitat loss and fragmentation from land development, and the loss of their host plants due to a fungal pathogen that harms one of the three host plant species. The fungus thrives in wet years, spreading within a lupine patch and killing plants that become overwhelmed.

In the park there are a couple distinct sites where we manage for MBBs. The one I saw the most this year is Sweeny Ridge, where the butterflies historically lived. The population disappeared for several years, so they were considered extirpated (locally extinct). About five years ago, the park started a long process of bringing the MBB back, starting with creating a welcoming space for it. The work has continued into the present; we expand the grassland habitat and plant lupin seeds that are less susceptible to the fungal pathogen. In the spring the hills are a mosaic of lupine shoots and wildflowers that serve as nectar sources for butterflies to feed on.


Once the habitat was restored enough to support a population, it was time to introduce new residents. With all the proper permitting in place, adult MBBs are captured from a nearby population and brought to Sweeny Ridge where they are released to repopulate their new home.  This spring was the second year of translocations at Sweeny, and there was evidence of MBBs born on site, evidence of success from last year!

This year, flight season lasted from April in to June. Translocation days were calm, sunny, and warm, the perfect weather for butterflies to frolic (especially since MBBs are relatively weak fliers). The first day we went out was sunny, but not quite calm enough. The wind kept the butterflies in hiding for the most part. We saw a few, but not enough to start collecting. Luckily, there were many more great days. It wasn’t lost on me how idyllic it was to be wandering about the grassy mountains with a butterfly net.

When we saw enough MBBs to catch, we would creep close to where one was perched and drop the net around the whole plant quickly but gently. Once it was in the net, you had to carefully get it into a plastic cup which would be sealed and labeled. Bonus points if you could catch a mating pair, since that basically guarantees the female will be ready to lay eggs in her new home. I never caught a double, but I was very satisfied with the number of singles I got. When we reached our catch limit for the day, we would put the cups with butterflies into a little cooler so they would be more docile and not injure themselves on the drive to Sweeny Ridge.

Once at Sweeny, we would find a nice-looking lupine for each individual. Then we put a mesh dome in place and released the butterfly into it so they could warm up, get used to the new environment, and hopefully lay some eggs. We watched each one for about an hour, then removed the mesh and let them do as they pleased. Just another day at the office.

Egg Monitoring

The job wasn’t finished once they went free, though. We came back once a week until two weeks after the last translocation to count MBB eggs on lupines. The eggs are about the size of a pin head, so it was a treasure hunt on each plant I went to. We used magnifying glasses to get a closer look at every plant that a butterfly was released on, as well as multiple random plants in the area. There were lots of eggs this year, which was very fulfilling to see. We even saw some that were hatched, with tiny little MBB larvae nearby.

Seed Collecting

As the project is ongoing, Mission Blue work has continued into the summer. My team has collected lupine seeds from our sites that will be cleaned and planted in the future to improve the habitat even more. We have also teamed up with other land agencies to collect seed that will be amplified (grown specifically to produce more seeds), creating a great deal more seed than we could easily collect. I have a lot of hope for the future of the MBB after seeing all the work that is put into their conservation.

San Bruno Elfin

The other special status butterfly I worked with is the San Bruno Elfin Butterfly (SBE), Callophrys mossii bayensis. It is endemic to the Bay area, even smaller than the MBB, and endangered. The butterfly is a pretty dull brown, and there are very few populations left. Like the MBB, it is a specialist on one plant: broadleaf stonecrop (sedum spathulifolium). SBE numbers have declined because of habitat loss and trampling.

This first picture is a sedum with no animals on it.

In our park we don’t know as much about the population dynamics and habitat situation of the SBE, so we are monitoring our sites to get a fuller picture so we can know how to help them. Our sites are all on or accessed by steep hillsides, because stonecrop is a succulent that likes rocky outcrops. These types of surveys don’t require any data about flying, so we only investigated larvae, which are much easier to track because they stay still and feed on the host plant. In fact, I never even saw a SBE butterfly. That’s fine by me, because the larvae are interesting in their own right. During a survey I would look in each rosette for something that barely stuck out from the gradient of pale red to pink to white. After a while I would be rewarded with a softer looking blob among the smooth leaves. Most of the larvae I saw were red or pink, but a few were yellow. To me they looked like berries or gummies, and I caught myself calling them lemon flavor and raspberry flavor. I can’t express how deeply I felt the primal urge to eat just one. I didn’t though. While there was no final product to reward my work, I was still pleased to be able to contribute to the ongoing monitoring of this endangered species.

That’s it. Butterfly season in words. Thanks for reading another one of these posts, here are some incidental pictures I took from butterfly days that I like.


  • pergamon
    Posted at 10:35h, 02 September

    Aw, this ѡas an incredibly good post. Taking the time
    and actual effort to prodսce a very good articlе… but what ⅽan I say…
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  • Elora Bossert
    Posted at 20:24h, 08 September

    Another great post as always Ivan. Looking forward to the next installment