It had been quite a while since the last time I visited Stebbin’s Cold Canyon in April, mostly due to the fact that the area had burned a few years ago and not much had grown back yet. However, the amazing start to the year, in terms of precipitation, had me wondering about a small group of moths that I had previously seen in the canyon a number of years ago. These small moths I had remembered were fairy longhorn moths, otherwise known by their family name Adelidae. They are a very unique kind of micro moth because they have very long antennae, sometimes two to three times their own body length. I knew Cold Canyon had populations of this moth because I had seen it here before, but I just couldn’t remember at what time during the spring they were in flight. Thankfully, a friend of mine had visited the canyon a few days prior and found multiple individuals of these amazing little moths, which meant that the hunt was on and finding them was now my top priority.
Dichelostemma capitatum is The Key!
My friend Alex Nguyen and I went to the canyon earlier in the morning than we had been going the past few times we visited, mostly because we wanted to beat the “rush” of people later on in the day. Fortunately for us the cool morning temperatures made photographing any insects we found much easier, due to the fact that they were cold and reluctant to move even after we approached them very closely. So, with this discovery we continued further into the canyon in search of the illusive fairy longhorn moths (Adelidae). My friend took me to the location he had first encountered them and after some thorough searching we eventually found them, much faster then I anticipated at that.
The fairy longhorn moths, also known as Adelidae, are a small group of moths found in most of the Northern Hemisphere. They consist of about 300 species worldwide with about 50 of those occurring in Europe and about 13 species combined from the US and Canada. Most species of these moths are diurnal and have at least some kind of metallic coloration on their forewings, while others are crepuscular and tend to be more dull colored. These moths are restricted to particular host plants and both females and males have a well-developed proboscis for nectar. They can sometimes reach great abundance in certain areas and their peak flying season is between mid to late spring. When I encountered them I would only see one at first but as I lowered my vision to that of the level of the moth I would see the other 5-6 individuals around it. There are only three species found in Stebbin’s Cold Canyon and I was able to find/collect two out of the three found in that area.
As my friend and I continued down the canyon trail we noticed a general pattern when finding these micro moths. They tended to be in open grassy areas that had bluedick flowers (Dichelostemma capitatum) and whenever we would see these flowers we would also find the moths. The plants that these moths use as hosts are in the family Polemoniaceae or the phlox family and these plants seem to grow in the areas near where bluedick flowers are found. So, whenever we would see bluedick flowers growing we would look for these moths and sure enough we would find them within minutes. This pattern continued all the way up the trail until we decided to turn back and head to the parking lot.
A Canyon Full of Surprises
After finding the Adelids and collecting a few specimens for personal records, my friend and I continued up the canyon trail to see what else was out and about. As we approached the creek we found a number of different flowers that were blooming and took note of the insects that were on them. From caterpillars to beetles, we continued to find different insect species on a variety of flowering plants, as well as under rocks and logs. To our surprise, we even uncovered a California Kingsnake (Lampropeltis getula californiae), which I had never seen before in the wild or in Cold Canyon. We encountered a few more insects before finding another location where the fairy moths were present. Of those insects was a robber fly (Asilidae), one which we had not seen in the canyon during previous years and were excited to photograph/collect it for a correct species identification.
As we moved a little further up the canyon, the weather began to change slightly and the temperatures began to drop slightly, which in turn reduced the insect activity once again. We ended up finding a canyon live oak tree and used an insect collecting technique called “beating”, where we used a stick to lightly hit a few branches of the tree in order to make insects fall onto my net for further identification. A number of different insects landed on the sheet including weevils, true bugs, wood-boring beetles, caterpillars, saw flies, and parasitoid wasps. After this we decided it was time to head back home, but on our way back to the parking lot I discovered a pipevine swallowtail butterfly ovipositing its eggs underneath a California pipevine leaf. This find was another first for me and I am very glad I was able to photograph this event while it was taking place.
This short adventure to Cold Canyon was surprisingly full of many new finds, and I know that as the season progresses there will be more and more days like this. I am looking forward to the plethora of other insect species that I still have to encounter within the canyon, especially the butterflies and moths that I have yet to find. There are many other flowers that will appear later in the season and I hope to document as many of those that are blooming as possible, so that I may obtain records for future reference when I visit the canyon at this time again next year.