Subject: Boring insect larvae in SoCal Mimosa tree
Location: Escondido, California
March 22, 2015 4:13 pm
We planted a Mimosa tree (Albizia julibrissin, a.k.a. Silk Tree) 6 weeks ago, and it just started budding out during the recent warm weather. Unfortunately, we are also now seeing insect larvae coming out of some of the small branches. Now that we know what to look for, we see dried up wounds in other parts of the tree, presumably from a previous season’s larval activity. The attached photo, showing active larvae, is of a branch about 1/2 inch in diameter. Can you identify this insect, and do you know of any treatment?
We are in Escondido, CA, which is 20 miles north of San Diego and 10 miles inland.
Signature: Joe Rowley
These are not wood boring insects. They are nymphs of plant parasitic Hemipterans, most probably Mealybugs in the family Pseudococcidae. You can use BugGuide for comparison. It appears that is a vile Argentine Ant in attendance. The invasive, exotic Argentine Ant will move plant parasitic Hemipterans from plant to plant, and they tend to them and protect them. We believe the plant was damaged, and the wound provided a food source for the nutrient sucking Mealybugs.