Gardening is an activity that requires you to use all your senses. The sense of smell for pest identification is often overlooked.
For several years, a fragrance emanating from a perennial border I tended eluded my identification. I sniffed and sniffed. At one time I thought it was coming from the seedpods of the Nigella or Love in a Mist. When crushed, the un-ripened seedpods of Nigella smell very much like artificial grape. This wasn’t the aroma.
While working in another bed, I smelled the same fragrance. Immediately, I wondered what the beds had in common.
Yucca. I went to the yucca plant and observed a bunch of bugs. Often, when people refer to bugs, they are talking about any insect. The insects I was observing were true bugs. I stuck my nose into the abyss and sure enough, I found the source. Later that day I went back to the original bed with the fragrance and that yucca also had an infestation of the same bug.
What are these bugs? I went home and goggled Yucca bugs. That was all I needed. The insect pest in question was appropriately named Yucca bug. For better pictures click this link.
Why the fragrance when these bugs feed? I do not know. I can speculate. I think it has something to do with Saponins that occur in yuccas. After the insect feeds on yucca the saliva or fecal material smells of cheap detergent. Saponins are detergent –like chemicals that occur in many plants. Yucca schidigera and Quillaja saponaria (soapbark tree) are two commercial sources for these chemicals.
You do not have to stick your nose right in a yucca to smell the aroma of feeding yucca bugs. If you do chose to use this method, watch your eyes. You are sure to get poked if you aren’t careful. A few days ago I was walking back to the barn at my parents house. The fragrance hit me. I turned and looked. A yucca was thirty feet away and loaded with yucca bugs.
They are fairly easy to control. I have used Pyola and soaps to knock them back. There are a few systemic insecticides that offer longer-term control.
Some sources say that the Yucca bug will not kill your yucca. This is partly true. If the plant is not in optimum growing conditions, I have seen the bug finish them off.