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COMMON NAMES:  Oak Leaf Sawfly, Sawfly, Tenthredinid Sawfly
SCIENTIFIC NAME:  Order Hymenoptera, family Tenthredinidae, many species

SIZE:  Adult--1/2", larva--about 1/4"


IDENTIFICATION:  Adults are small wasps that cannot sting. The name comes from the sawlike structure at the end of the female's abdomen, used to cut into leaves to lay eggs. Larvae look like translucent slugs, usually yellowish green and shiny with black heads. Some are covered with a slimy material.

BIOLOGY AND LIFE CYCLE:  Females lay eggs on the back side of leaves. Larvae hatch and feed on the tissue between the veins, causing a skeletonized effect. Larvae overwinter in cocoons.

HABITAT:  Red oaks and white oaks primarily.

ECONOMIC IMPORTANCE:  Damage is usually spotty on trees and not significant.

NATURAL CONTROL:  Enemy insects. Biodiversity.

ORGANIC CONTROL:  Microbial disease products, horticultural oil, and citrus oil products.

INSIGHT:  You see some of this damage every year, but it never seems to be anything other than cosmetic and temporary. Some sawflies attack and damage fruit trees, elms, roses, and pines.

  What bug does this to my citrus trees?  I'll look up in your bug book if I knew what did it.  C. N. New Braunfels, TX
A.  Looks like the work of some type of caterpillar or sawfly. The same organic pesticides don't necessarily work on both these insects. Insecticidal soap will work on both for low populations of young larvae. Bacillus thuringiensis (Bt) will kill the larvae (caterpillars) of butterflies and moths but will not control sawfly larvae. Trichogramma wasps will always be helpful for the caterpillars but not so much for the sawflies that do not turn into moths or butterflies. Their adult stage is a type of fly related to wasps and bees. The difference? Caterpillar’s head end is sometimes hard to tell from tail end. Caterpillars have fake eye spots (real eyes are microscopic) and the head is often not obvious. Sawfly eyes are easily visible and the head is obvious. Caterpillars have 3 true legs up front and then 5 or fewer pairs of prolegs which are fleshy extensions. Sawflies have the 3 pairs or true legs up front and 6 or more pair of the false legs toward the rear. Maybe more detail than you wanted but it's interesting stuff. To kill the sawflies, use quality neem products, citrus-based products or spinosad. Spinosad products are probably the most effective on both these pests. However, spray spinosad surgically on the affected plants and not all over the entire garden. Spinosad is an excellent organic insect control but can disturb the navigation of beneficial pollinators such as honeybees.

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