Island Entomology

Mike Valainis and Bret Robinson, SJSU Entomology students

My name is Bret Robinson and I am a graduate student at San Jose State University.  I have been taking multiple boat trips out to the bone, guano, and insect covered South East Farallon Island for almost a year now.  I, along with Mike Valainis - another San Jose State grad student, am investigating the insects of the island. Mike is concentrating on the endemic cricket species Farallones caverniculus. 

My thesis is more general and will provide a baseline for further entomological studies and identifications of Farallon insects. I collect, and then determine, what species are found throughout the year.  Seasonality is observed through frequent trips that last roughly two weeks.  I collect insects found on the island and those traveling to the island from the mainland.  I’m also examining the abundance and diversity of insects on the Farallones before potential proposed eradications of invasive plants and mice.

Farallon collections from spring 2013

So far, we have found a diverse array of multiple orders of insects on the island.  Three main orders seem to dominate the insect biodiversity. These are Diptera (Flies), Coleoptera (Beetles), and Lepidoptera (Moths/Butterflies).  

You wouldn't think that there were many different flies since throughout the year you are bombarded by the infamous "Corm" Fly, Fucelliinae thinobia, but so far it is the most diverse order. Many of these flies are mere millimeters in size.

Beetles are also a dominant species on the island. Two beetles in particular are the Darkling beetle, Eleodes planatus or the black beetle of the genus Coniontis. Any time you lift up a rock your chances of finding one of these are high.   

Farallon "Corm" Fly
Fucelliinae thinobia

Everyone loves Butterflies and this island’s got them.  Observations have determined that most butterflies are migrants and they are taking to the wind and making it all the way out to the island.  Two butterflies species have successfully set up a permanent residence here on the Farallones by taking a liking to the Mallow plants, Lavatera arborea and Malva neglecta.  These two butterflies are; painted lady, Vanessa cardui and the west coast lady, Vanessa annabella.  These butterflies will dance around you as you take a leisurely walk through the marine terrace on a warm sunny day.

West Coast Lady, Vanessa annabella

Butterflies are cool, however it is the other Lepidoptera group, moths, which excite me the most.  There are micro moths that take residence in the caves and just love feeding on that nutrient rich guano.  Among these you will find day and night a variety of larger moths that seem to appear during certain seasons.  With an ever-changing island of macro species, birds and pinnipeds,  there is right under our noses a diverse changing group of moth species throughout the year.    

Yellow Hindwing Moth, 

Noctua pronuba

All in all there is more out here on the island than we could ever dream.  Many specimens have been collected and now with the help of an academic community of experts such as Universities and organizations like Cal Academy we can identify these amazing creatures 

I can’t wait to get back on the Island in January for another insect expedition and to see those massive male elephant seal behemoths duke it out for love.