What kind of larva is this? (Southern CA, USA)

Question

I need help identifying this larva:

(Click images for full size versions).

There's about a dozen of them in my parents' bathtub and I'm not sure what they are or where they are coming from.

They are about a centimeter long, maybe a little less. They look flat and are hardly noticeable. When they are upside down they look more like a maggot.

My parents didn't even notice until I pointed them out. They move around very little and stay at the bottom of the tub. I haven't seen them anywhere else.

Answer 1

That looks a lot like a Common Southern California Termite. I would check any wood that you have around your home just to prevent any damage. If you want more information just look it up online, but that's most likely what it is.

Note the eyes, the short, segmented antennae, the mandibles (better seen in your second photo.)

Answer 2

Short Answer

These look like termites, and based on appearance and size they are likely Drywood Termites of the family Kalotermitidae.

• Specifically, these appear to be either workers or "pseudergates$^†$", and likely those of the species western drywood termite (Incisitermes minor).

  

  ^{Source: UCANR}

However, without mature soldier or swarmer specimens, conclusive species ID is very difficult.

Long Answer

General Termite ID

According to Orkin, there are 3 distinct groups into which termites are divided: subterranean, drywood, and dampwood.

Since the worker termites in these groups more or less look the same, the appearance of the reproductive caste (alates) [or swarmers] and soldiers is important..

• In other words, it will not be possible to properly ID your specimen without pictures/descriptions of the soldiers or swarmers.

However, It is critical to identify the species of destructive termites to formulate an appropriate control program.

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According to this UC IPM page, there are at least 23 different species of termites in California.

I'll give you support for the options that I think are most likely:

Option 1:

My initial guess is that you have some species of drywood termite (family Kalotermitidae), because these are common.

• Based on the following picture (and numerous others from a google search), your specimen looks more like the size/shape of a drywood species vs. either dampwood or subterranean:

  

  ^{Workers (from left to right) of subterranean, Reticulitermes hesperus; drywood, Incisitermes minor; and dampwood termites, Zootermopsis nevadensis. [Source: UC IPM].}

• Without swarming specimens, further confirmation will be difficult.

  • However, drywood termites have very distinct hexagonal 1mm-long fecal pellets called frass that you could try to locate to confirm.

  

  ^{Zoomed in frass (or fecal pellets). Sources: Termiteweb and UC IPM}

  

  ^{Fecal pellets collecting under a door Photo by B.J. Cabrera, University of Florida}

• Do you have this??

However, even given that initial guess, another UC IPM page suggests that drywood termites are not often seen:

Drywood termites are cryptic insects that are difficult to detect. They live deep inside wood; and except during periods when they swarm or when repair work is being done on infested homes, they are seldom seen.

• So my guess could be wrong....

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Possible Candidate Species

If your specimen is a drywood species, it is most likely the western drywood termite (Incisitermes minor).

^{Source: Himmi et al.(2016)}

From UC Berkeley:

Pest Status: Second most destructive termite in California.

• Key Characteristics:

  • Present throughout California, but most prevalent in southern CA.
  • ~ 1 cm long
  • Live in and eat dry wood (typically found throughout wooden structures of homes)
  • Nests of most species remain entirely above ground and do not connect to the soil.

For more info, see here.

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Option 2:

Subterranean termites (typically of the family Rhinotermitidae ).

• Shelter tubes (sometimes called mud tubes) are the most commonly seen evidence of a subterranean termite infestation.

  

Common species:

• Western Subterranean Termite (Reticulitermes hesperus) [also see here].

  • The most destructive termites found in California [Source: UC IPM page].

  • Unlikely your species because they typically are only about 0.3 cm long. [Source: Termite.com].

• Formosan subterranean termite (Coptotermes formosanus)

  

  Source: Nolawoman

  • Invasive termite from China, that has invaded US (including CA).

  • Nicknamed the super-termite because of its destructive habits due to the large size of its colonies and its ability to consume wood at a rapid rate

  • Again, these are likely too small to be your specimen as the body length is approximately 4-5 mm. [Source: CABI].

Conclusion

Based on size, it is more likely that you have a drywood species vs. a subterannean species.

However, again, without more evidence (frass vs feeding tubes and/or pictures of mature soldiers/swarmers) a definitive ID will be difficult.

I advise that you contact a local exterminator or termite expert to have them check your parent's house more closely.

Good luck!

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$^†$ _{Note: "pseudogate" = a blind wingless nymph performing some of the functions of a worker. [See here].}