You are here:

Entomology (Study of Bugs)/Unknown bug invasion - can you name it?


Myster bug in Half Moon Bay
Myster bug in Half Moo  
Hi, I recently moved to the California coast, about 1 mile from the shore between Santa Cruz and San Francisco. In the past 1 or 2 weeks, there was a bloom of tiny bugs swarming the ground (grass, dirt, and stone patios) once the day warmed up, and I've noticed them on the window frames as well although not inside the house.  They range between .75mm to 2mm in length with 6 legs and antennae that are about half the length of their bodies. They move pretty quickly when interrupted, and otherwise march around tirelessly looking like they're combing the surface for something.  At other times they seen to zig-zag in short bursts across the surface, and avoid climbing onto objects placed in front of them (while trying to catch some in plastic bags, cups, sheets of paper to inspect them closer).  Do you have any idea what they are and if they should be something to be concerned about?  (i.e., would they like to eat me, my pets, or the structure of my house), Or could they be beneficial?  Do they like to eat aphids?

Thank you!  If you'd like me to try to get a better picture I can try...


Thank you for including the image with your question.  Unfortunately, the insect depicted is an immature (nymph), and such a life stage is exceedingly difficult to identify.

My highly educated guess is that it is one of several recent "immigrant" species from Europe, possibly this one:

But, I would take some intact specimens to a local entomologist at the Cal Academy, university (UC Davis), or state agriculture office and have he or she look at them under a microscope to render a concrete verdict.

Most of these bugs are classified as a mere "nuisance pest," but it might pay to have them checked out just to be sure.



Entomology (Study of Bugs)

All Answers

Answers by Expert:

Ask Experts


Eric R. Eaton


I answer insect and spider identification questions ONLY. Attach images if possible. No "what bit me?", "what do I feed this bug in captivity?", or science fair project questions please. NO TECHNICAL QUESTIONS ABOUT INSECT PHYSIOLOGY.


Principal author, Kaufman Field Guide to Insects of North America. Professional entomologist employed previously at University of Massachusetts, Chase Studio, Inc., and Cincinnati Zoo; contract work for West Virginia Department of Natural Resources, Smithsonian Institution, and Portland (Oregon) State University.

Author, Kaufman Field Guide to Insects of North America, Missouri Conservationist magazine, Ranger Rick, Birds & Blooms, Timeline (journal of the Ohio Historical Society). I have contributed to several books as well.

Oregon State University, undergraduate major in entomology, did not receive degree.

Awards and Honors
One of the top 50 experts in all categories for, 2009.

Past/Present Clients
Principal author of the Kaufman Field Guide to Insects of North America, Smithsonian Institution (contract), Cincinnati Zoo (employer), Portland State University (contract), Chase Studio, Inc (employer), Arkansas Museum of Discovery (guest speaker). Currently seeking speaking engagements, leadership roles at nature festivals, workshops, and ecotours.

©2016 All rights reserved.