One hungry larvae

One hungry larvae

As I turned on to my driveway lined with Long Leaf Pines I had planted almost four years ago, I was shocked. My trees were devastated. At first glance, not knowing what exactly could have perpetrated this act, I jumped from the truck to investigate up close.

Infestation of the Pine sawflies - The trees were covered by approximately one inch, yellowish green, black spotted caterpillars.

The trees were covered by approximately one inch, yellowish green, black spotted caterpillars. I quickly thought, what the heck kind of bug eats a pine needle? After inspecting the trees that were plucked clean of every needle from top to bottom, it became clear to me they were on the move - one tree at a time until they devoured them all.

I quickly grabbed an empty water bottle from the truck and scraped off a few. I thought for sure the local Division of Forestry office would be interested in this beast of a vegetarian. After arriving at the Division of Forestry Macclenny Station, Andy Lamborn, local Forester, quickly identified the little critters as one of Florida’s notorious forest insects known as the Pine Sawflie, the red headed version to be exact.

Sawflie? But this is a worm.

Lamborn, quickly went to his computer and pulled up a fact sheet on the critter. Pine sawflies is a group of several species that defoliates pines in Florida and throughout the South. Sawflies usually attack only one tree or a small group of trees.

Sawflies prefer 5 to 10 year old trees, and with repeated attacks over two or more years can cause a tree to die but the greatest damage caused by pine sawflies is loss of tree growth. They

One of the healthy trees left

create this damage by eating the needles of pines. How do they work? "In spring, female sawflies lay their eggs in the needles of pines. The female can actually cut an individual slit for each egg and can create 1 to 30 slits for eggs in one needle", Lamborn said.

Lamborn went on to explain, "Larvae hatch from the eggs to eat the pine needles. Fully-grown larvae drop from the needles to the ground and spin cocoons in the soil. Sometimes larvae do not drop from the tree but remain to spin their cocoons in the branches and needles of the tree. This is common when the ground is flooded. Adult sawflies emerge from the cocoon weeks, months, or even years later depending on the species."

Okay, how do I kill them?

"Sawfly larvae are easily killed by most broad spectrum insecticides, insect growth regulator, botanicals, or insecticidal soap or oil. There are also some reports that spraying with a high pressure hose knocking them off the tree is a very effective method of control. The most effective control is achieved when pesticide is applied early in the season when sawflies are young. After the sawflies reach one inch in length, they stop feeding and construct a pupae." Lamborn explained.

Defoliation by this insect pest generally lasts four to five weeks, the good news is there is only one generation of sawflies per year.

Result of the infestation

For more information about our local forests and pest that may inhabit them,

visit the Florida Department of Agriculture and Consumer Services - Division of Forestry web site at: www.fl-dof.com