California mystery cockroach

[Arachnocat]

Can someone please ID these roaches for me? I found them in Santa Rosa, California. They're small, about .25" and appear to be adults. I originally thought they were nymphs because of their size and they resemble german roach nymphs. However, one of them is laying an ooth!
Hope someone knows what they are!

[ahas]

Nice patterns.

Fred

[edwbaker]

Blattella asahinai

[Orin]

Originally Posted by edwbaker

Blattella asahinai

You know that species doesn't have short wings, right?

[Megaloblatta]

Orin's right - it is not Blattella asahinai (sorry Ed!) - that species has long wings. At the moment I can't identify it, but I'm working on it!

[edwbaker]

There was meant to be a question mark there! It's the only Blattella sp. I knew of from the area that wasn't germanica.

There is an apterous form of germanica reported from the US?

[Megaloblatta]

I am pleased to say that I think I have identified it. It is Phyllodromica (Luridiblatta) trivittata (Serville, 1839) which is known from dry habitats around the Mediterranean. It has been recorded from Morocco; Algeria; Spain; Italy (Sardinia Island); Italy (Sicily); Libya; and Israel. Given that it has not been recorded as being a pest in buildings in those countries (as far as I'm aware) it is unlikely to invade buildings in the USA - although who knows what else it might do!

George Beccaloni
(The Natural History Museum, London, UK)

[Megaloblatta]

Just to say that I have now studied an illustration of the female of this species in a paper by Ignacio Bolivar in 1921, plus a specimen we have in our collection, and the female shown in the photos above is identical.

It is of course possible that there are two of more identical looking species which can only be differentiated by examination of the male genitalia or other methods. However, since it is likely that such close relatives would be found in the same geographic region this means that the Californian population almost certainly originated from the Mediterranean region.

George

[BoogleBug]

Wow... those are beautiful!

[heywatchit]

I moved to San Rafael CA in 2000. My wife and I did not notice them until a few years after we moved in. They appear every year in late summer and disappear in late fall/early winter. They mostly stay outside the house but we do find a few inside. I'm wondering why they come and go with the seasons and how they got here. Is there something about the weather that makes them come and go? And if they are not typical to this area how did they get here?

FYI I am not an enthusiast just an curious homeowner