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Caterpillars on Ash tree

Caterpillars on Ash tree
Laredo, Webb County, Texas, USA
March 9, 2005
Size: 1/2 to 1 inch (12-25 cm.)
I noticed these on several ash trees in Laredo Tx. on March 10, 2005. They appear to be moving from ground level up trunks and consuming the leaves (new growth)of the trees.

Images of this individual: tag all
Caterpillars on Ash tree Caterpillars on Ash tree

Moved from Sawfly larvae. Both Tethida cordigera and Tomostethus multicinctus are in Blennocampinae.


I've never seen anything like that. Given that they have more than 5 pair of prolegs, they appear to be sawfly larvae of some type.

I'm checking Garden Insects of North America (1), and there are some good possibilities mentioned: the Blackheaded ash sawfly, Tethida cordigera and the Brownheaded ash sawfly, Tomostethus multicinctus.

Awesome find!
I've never seen or heard of anything like that either. Wonder what caused the gathering.

Right on
Certainly one of these: blackheaded have black heads (!) and whitish bodies tinged with yellow; brownheaded have (you guessed it) with greenish or yellowish white bodies. They both overwinter in the soil at the base of the tree. So the choice is black or brown heads.

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