What insect is this?
I found this insect in our kitchen and it's body is around 1 cm long (maybe a bit more). Could you identify it and provide any information about e.g. if it is usually isolated or where it nests? Thanks!
Your mystery insect is a cockroach, and appears to be the one known as the German Cockroach (Blattella germanica). This species is the most common indoor cockroach in California, and those two dark stripes on the shield above the head are distinctive among indoor cockroaches here. Despite its name, the species apparently originates from either Africa or southeast Asia (opinions differ; in any case it's not originally European) and has spread across the globe through being an extremely successful co-habitant with human beings.
Unfortunately in your case, where there's one, there are many. While not a strictly social insect like honeybees or termites, the German Cockroach does live in large groups and reproduces very quickly, completing its life cycle (that's egg to egg-laying female) in 6 weeks or so; this, combined with being able to live in almost any concealed space and eat almost anything even resembling food, is probably the secret to its success.
The specimen photographed is a nymph, which means it is not fully grown. Adults of the German Cockroach, both males and females, have long wings that cover the abdomen and extend past the rear end. They grow to about a half-inch long (1.3 cm or so), which is not very large as far as cockroaches go. Nymphs like yours have only short, stubby wing buds. The funny-looking ear-like appendages at the rear end are called cerci—these function as sensory organs, helping the cockroach detect vibrations and subtle air currents, thereby keeping it alert to danger.
California has many species of cockroaches, but only a couple of species are indoor pests. The remainder may be found in places like gardens, dead logs, leaf litter, and there are even some specialized for "swimming" through sand dunes!
Thanks for sending,
Schlinger Foundation Chair and Curator of Entomology Matthew L. Gimmel, Ph.D.