The Bug Blog

The purpose of the Bug Blog is to provide information about and a forum for discussing the insects and other arthropods commonly encountered in Marin and Sonoma counties. Insect identification is a free service offered by the Marin/Sonoma Mosquito & Vector Control District. If you have an insect or arthropod that you would like identified, you may mail it to District headquarters (attn: Eric Engh) or drop it off (in an enclosed container) at our front desk during regular office hours. Specimens will be identified as time permits.  

Velvet ant ("cow killer")

Where found: 
Trapped in a flower cup at a gravesite in a cemetery in San Rafael
Approx. 1 cm long
Scientific name: 
Dasymutilla spp.

Sometimes names can be misleading. Velvet ants are not ants—they are actually wasps, and even though females can inflict an extremely painful sting, they don’t actually kill cows (as far as we know). The individual in the photo is a female.

She might be fuzzy and cute, but don't ever pick up a velvet ant!

Female velvet ants have a powerful sting!

Three-lined roach

Where found: 
In the kitchen
Approx. 5 mm long (body length)
Scientific name: 
Luridiblatta trivittata

One summer evening in 2011, my wife caught a small insect scurrying around the kitchen floor. I took a quick look and immediately transformed into a cockroach-hunting/cleaning maniac.


Luridiblatta trivittata: tri = "3", vitta = "band or stripe"

Three-lined roaches are flat enough to slip under doors

An egg case (ootheca) from a three-lined roach

Western black-legged tick

Where found: 
Natural areas
Variable (depending on life stage)
Scientific name: 
Ixodes pacificus

What bloodsucking creature begins life with 6 legs, grows 2 more legs after feeding on blood, has no eyes, but can sense you walking down the trail?


Western black-legged ticks

Tick nymphs are tiny!

Tobacco hornworm

Where found: 
In a Rohnert Park tomato garden
Approx. 80 mm long (mature caterpillar/larva)
Scientific name: 
Manduca sexta

In the fall, a resident brought us a massive hornworm he had found on a tomato plant in his garden (see photo). Hornworms are the larval (caterpillar) stage of a moth with a wingspan of up to five inches.

Our hungry green giant, the tobacco hornworm

Hornworm pupa

The hornworm was not as healthy as we thought!

Oak moth

Where found: 
On and around coast live oaks
Approx.13mm long (body length)
Scientific name: 
Phryganidia californica

Oak moths are the adult stage of the California oakworm.

An adult California oak moth

Two pupal cases- the yellow one is newly formed