We were watering Pentas earlier this week and came across this funky looking fellow (above). At first, we thought it was a more common Tomato Hornworm, but after doing some research, it’s a Tersa Sphinx (Xylophanes tersa) caterpillar! Actually, both in the photo are Tersa Sphinx caterpillars at different stages. Pretty soon they’ll transform into their beautiful moth form.
![](https://gillnursery.com/wp-content/uploads/tersa-sphinx-moth-938x1024.jpg)
Caterpillars have been a big topic of conversation here at Gill’s this Summer; more rain than usual = more caterpillars. A good rule of thumb is to leave them alone unless you see a large congregation and they’re eating enough of a plant to cause harm. A few munched leaves here and there is not a problem. If you do get a large infestation, you can treat with organic Thuricide that only targets caterpillars.
Most different species of caterpillars are only attracted to specific host plants. Pentas are a host plant for the Tersa Sphinx, which was a big clue for identification. We know that Monarch caterpillars like milkweed, Gulf fritillary’s host plant is Passion Vine, and Swallowtail caterpillars like Rue and Dutchman’s Pipe Vine.
![](https://gillnursery.com/wp-content/uploads/monarch-1.jpg)
![](https://gillnursery.com/wp-content/uploads/gulf-fritillary-caterpillar.jpg)
![](https://gillnursery.com/wp-content/uploads/black-swallowtail-caterpillar-1024x682.jpg)
Once caterpillars reach their butterfly or moth form, they feed on nectar from a broader variety of South Texas plants like Lantana, Zinnia, Mist flowers, Turk’s Cap, and lots more. So, it’s a good idea to plant host plants and nectar plants together to enjoy the caterpillar’s full life cycle.
![](https://gillnursery.com/wp-content/uploads/Jesse-Jenkins-300x300.jpg)
-Jesse
Cristina says
I’m new to Texas and this morning found 100’s of small orange fuzzy (i assume caterpillars) on my live oak. I appear to be the only one on my street with them. Your advice would be greatly appreciated!
Jesse says
Hi Cristina – not to worry! Their life cycle is only about 2 weeks. They will not affect the health of the tree, and they’ll be good food for birds. If you decide they’re too much of a nuisance, you could spray with organic BT. Or you could just wait them out.