A Lac of Interest

Because creosote is so common and grows literally everywhere here on the desert, I often tend to overlook it. My mistake.

The other day it surprised me. As I passed by yet another bush of same-old-same-old, I spotted several lumps on two of the branches. I was stumped. They were hard and dry and asymmetrical. What were they?

It took a chance encounter with a docent at the Arizona-Sonoran Desert Museum to find the answer. This was the work of lac insects. (If shellac comes to mind, it’s because this insect is related to the one from which that varnish and sealant is produced.)

The work of lac insects

The tiny lac insects suck up sugary sap from the creosote, using some for food and eliminating the rest. As the sap hardens it forms a natural protection against predators and the weather.

Although I checked the two branches carefully I couldn’t see any live insects.  Nor could I see any ants, who sometimes protect lac colonies from predators, “milking” them like cows, just as they do with aphids.

The lesson for me? Don’t ignore what’s right under my nose. 🙂


Lac insect   Tachardiella larreae
Creosote   Larrea tridentata

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