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Saturday - June 05, 2010

From: Austin, TX
Region: Southwest
Topic: Diseases and Disorders
Title: Beetles in spineless prickly pear in Austin
Answered by: Barbara Medford

QUESTION:

I have an enormous spineless prickly pear in my front garden. It's about 6 feet tall, and 6 feet wide. It has blossoming yellow flower. However, it also has large colonies of black beetle-ish bugs living on it. The are in large clumps of the beetles on certain pads in the shadier parts of the cactus. The pads on which they spend most of their time are generally more pale than the other pads. So, A) what the heck are these beetle things? and B) should I try and get rid of them? How?

ANSWER:

We are not entomologists and this is out of our line; however, we did some Internet searches in an effort to figure out what was going on with your Opuntia ellisiana (tigertongue). The creature that sounded most like your description is described on this website from Arizona Wild Flowers Cochineal Beetle. Most of the sites we found on this beetle were more interested in the fact that red dye could be made from the beetle (yuck) than what to do about the thing.

From the University of Florida Featured Creatures comes this article on Chelinidea vitttiger aequoris, which is actually being studied as a way to control invasive members of the genus Opuntia, prickly pear, especially in Australia. This article, Bug Guide Prickly Pear Fruit Beetles shows a very glossy black beetle on an Opuntia pad.

And, finally, here is an article by Badii and Flores, Prickly Pear Pests and their Control in Mexico. Our eyes glazed over.

Through all of this, we're still not sure we found the bug you describe. You can try looking at Images of Cochineal beetle from Google, and see if they match up to the beasties on your cacti.

We would suggest, if you don't identify your bug with anything we supplied, that you contact the Texas AgriLIFE Extension Office for Travis County. They do work with entomologists and may even have a printed bulletin about this pest, especially if you are not alone in having the infestation.

From our Native Plant Image Gallery:

Opuntia ellisiana