What's That Bug? does not endorse extermination

Invasion Phuket : The Next Wave – 26.01.10
January 26, 2010
Hi Daniel,
Greetings from Phuket once again and a belated Happy New Year for 2010.
I’m not sure if you remember, but I contacted you in December 2007 with regards to an infestation of Atticus Atlas (in the large and slightly scary larval stage) at one of the properties we manage.
Today we have another infestation at another property that we manage involving these hard to discern little chaps, please see the attachments.

Unidentified Caterpillars: Early Instar???

We would be most grateful for your identification skills so that we can establish if they are friend of foe. Needless to say – the Villa Owners are not too keen on them as their pools are becoming clogged with caterpillar droppings.

Caterpillar Droppings

Thanking you once again for your assistance.
With kind regards,
Mark.
Phuket Branch, Thailand

Unidentified Caterpillar

Hi Mark,
We fondly remember your Atlas Moth Caterpillar letter quite well.  This current request will take some research, and we may just post it as unidentified and turn our readership loose since we have two pressing letters to write this morning to local city councilmembers.  We would like to request some additional information, mainly, the species of tree that the caterpillars are feeding upon.  It looks like it might be some species of fig.  That would greatly assist in the identification process.  Also, in one image, there are a great number of Caterpillars.  Is that a grouping of smaller, younger individuals?  We cannot find a match on the caterpillar page of the Thai Bugs website.

Unidentified Caterpillar

Update from Karl
Hi Daniel and Mark:
The host tree looks like a fig, possibly Ficus retusa, and I am fairly certain the caterpillars are Bombycidae (Silkworm Moths). Beyond that it gets difficult but I think the most likely candidate genera are Trilocha or Ocinara, both of which feed on fig trees and are common in southeast Asia. These genera are very closely related and may even be synonymous, at least for some species. The thoracic swelling that is evident, particularly in the smaller individuals, is common among Bombycidae larvae. The smaller ones also appear to have a caudal horn, another common feature. I don’t see a horn in the other photos but the angles are wrong and, in any event, these horns typically get shorter or disappear as the larvae grow. The head region of the larger individuals looks similar to another related species, the Domestic Silkworm Moth (Bombyx mori), which does not occur in the wild.  If I had to guess I would go with either O. albicollis or T. varians, which may in fact be color variations of the same species, according to some sources. Reference photos of larvae are difficult to find and the adults would likely be easier to identify, so perhaps you could submit another photo when they emerge. Regards.
Karl

Dear Daniel,
Thanks for the information.
My team are currently trying to identify the tree in question. As soon as we get a handle on it we’ll let you know.
In terms of treatment, do you have any recommendations ? As you know, I’m loathe to terrorise them with a toxic, chemical bath. If we leave them alone, will they eventually go of their own volition ?
Thanks again for your superb help.
With kind regards,
Mark.

Hi Mark,
If this is the first year that they appeared, it is probably just a seasonal population explosion.  They will probably mature shortly and then their population will return to its normal numbers.  We would refrain from extreme chemical measures.

Hi again Daniel,
My on site team have given it their best guess as a Ficus benghalensis.
Please see the link below.
With kind regards,
Mark.

Cheers, Daniel.
Music to my ears.
Have a great day and all the best,
Mark.

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