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July 19, 2018

Dear Skyliners,

Over the last week, we've pretty much mopped up Scattergrass in the Bay Grove and moved on to Spurge (Euphorbia oblongata) in the Water Tank area.  Spurge has been a new invasive for us to figure out.  Last year, we uprooted all the large, perennial plants along the trail and on the slope above the Water Tank and put them in big piles.  This year, there was a large crop of seedlings, but not around the piles, interestingly.  These seedlings flower the first year, so twice this year, we've cut off the flower heads, and now we're digging them out.  It's going well, but it needs a lot of hands - we'll be at this for awhile.

We'll be out again on Thursday (our new regular mid-week day) at 4pm and Sunday at 9:30 am this week.  Please let me know if you can make it.

Earlier this month, we held another Moth Night at Skyline with the help of the iNaturalist folks.  The basic ingredients are a warm, calm night, a white sheet and a UV light, which attracts the insects.  Here's the set-up:

 

This time we set up three sheets along the trail between Steam Trains gate and the Siesta Valley Overlook bench.  It was quite a scene.  The glowing sheets and a dozen people floating back and forth along the trail with flashlights reminded me of the elves and Rivendell in the Lord of the Rings movies.  

 

And species, oh, my!  We encountered over seventy species of moths and other insects that you just would never see in the daytime.  To be able to peer into the life of darkness and see worlds unimagined is a thrill in itself.  But if we look deeper, every moth (and butterfly) has their own, very specific host plants, or larval food plants, which the caterpillars must eat to survive.  So learning that is also part of the exploration.

 

Here are some of the stars of the evening.  First, here is California Lichen Moth (Bryolymnia viridata):

This time we set up three sheets along the trail between Steam Trains gate and the Siesta Valley Overlook bench.  It was quite a scene.  The glowing sheets and a dozen people floating back and forth along the trail with flashlights reminded me of the elves and Rivendell in the Lord of the Rings movies.  

 

And species, oh, my!  We encountered over seventy species of moths and other insects that you just would never see in the daytime.  To be able to peer into the life of darkness and see worlds unimagined is a thrill in itself.  But if we look deeper, every moth (and butterfly) has their own, very specific host plants, or larval food plants, which the caterpillars must eat to survive.  So learning that is also part of the exploration.

 Here are some of the stars of the evening.  First, here is California Lichen Moth (Bryolymnia viridata):

Just look at that coloration - just like lichen.  I can't imagine better camouflage.  They are about one inch long.  And it turns out that the larvae of these moths actually eat lichen.  These moths are pure Californians, and are found in the Coast Ranges from Sonoma County south to San Diego area.  If you've ever looked at the lichen on Coast Live Oaks, these are just a perfect match. If anyone knows more about this, please drop a line.  I find this all just fascinating. (Thanks to Cynthia for the photo.)

 

 Here's another western moth, Pacific Slant-line (Tetracis cervinaria):

This is one of the Geometer moths, and is found in the Pacific Coast states and in the Rockies.  The wing span here is about two inches. (Thanks to Ken-ichi for the photo.)  Their larval food plants?  They feed on our native Prunus, both emarginata and virginiana.  The closest location of these shrubs, and the only place we've ever found them in Skyline Gardens, is on the slope above the trail to the west of Fish Ranch Road, which is way over Barberry Ridge.  Are there more native Prunus down in Siesta Valley?  It's always this way in nature, one question answered poses yet another...We saw more than moths.  Here is Giant Water Scavenger Beetle (Hydrophilus triangularis):

We found this one at the bottom of the sheet, on the ground.  This one is about two inches long, and yes, they can fly.  These are primarily aquatic insects, the larvae grow in water.  Both adults and larvae are carnivores, and they eat any small insects and such that they can find.  They are known for being attracted to lights, so we guess this one flew up from the creek in Siesta Valley.

The night was also good for spiders.  Have you ever noticed those silk-lined tubes along the shoulder of a woodland trail?  They look like this:

The tubes are about a quarter to a half-inch in diameter, and they are built from debris and lined with spider silk. (Ken-ichi photo)  They even contain a trap door.  Tony used a grass seed head and lured one out:

Yeow - look at that!  This is another native creature, California Turret Spider (Antrodiaetus riversi).  They are nocturnal, and they lie in wait inside the tube, or turret, and wait for the vibrations of night wandering prey.  Then they pounce.  This one was about two inches long, and they are cousins of Tarantulas.  Great photo, Tony.


We'll close out the journey to the dark side with this tiny moth, Caloptilia diversilobiella:

This one is about half an inch long, and they rest with a distinctive posture, the front part of the body raised high on the forelegs. This is yet another true-blue Californian (Ken-ichi photo).  And here's one with wings spread collected in Briones by UC's moth expert Jerry Powell: 

Caloptilia means "beautiful wings" and I think they got that right.  

 

Now what do their larvae eat?  Look again at the species name.  Yes, Poison Oak!!  The larvae of little Caloptilia are leaf miners and they feed on Poison Oak leaves.  Leaf miners are caterpillars who eat the plant tissue between the upper and lower surface of a leaf.  Leaf mining moths have been on this Earth for nearly 100 million years, doing just that, on many different plant species.   


Isn't it remarkable how Poison Oak has its own, special leaf miner?  How tightly nature is knitted together.  

So the next time you start to feeling blue, remember little Caloptilia.  It's a big, old world out there.

Happy Trails,

Glen