Defoliators Continued: Gypsy Moth and Sawflies

The gypsy moth: Lymantria dispar L. A world class problem: another Lymantriidae

The Gypsy Moth, Lymantria dispar L. Gypsy moths are native to north Africa, all across eastern and western Europe, across Siberia, the Russian Far East and on into Japan. What an enormous range? enormous gene pool With this enormous gene pool, it’s small wonder that gypsy moths consume the foliage of practically any hardwood.

Gypsy moth biology, ecology and control has been studied for a long time, especially in Europe.

An opening statement: A single instance of complete defoliation can kill conifers, i.e. white pine, and eastern red pine. Three consecutive defoliations kill deciduous trees, especially the oaks.

Defoliation of eastern oak white pine forests by the gypsy moth – heavy oak mortality.

The pest was brought into the U.S. by an artist, amateur astronomer and biologist, Leopold Trouvelot. Trouvelot lived at 27 Myrtle St. in Medford, Mass. He wished to cross the gypsy moth with the satin moth and start a silk industry in the U.S. In 1889 some moths escaped, and the rest is history!

American Naturalist Vol.1, pp

Etienne Leopold Trouvelot and his house on 27 Myrtle St., Medford, MA. His gypsy moths escaped in Medford Fire Department cutting and burning dead oak trees.

Medford, MA courthouse and its famous oak trees, and they are dead. The first demonstration of the power of the “Gypsy Moth.”

20 yrs later!

Spread fast across the U.S.

Spread: Eggs are laid on anything, including cars, campers, outdoor furniture, tent folds etc. If the larvae don’t land on their hosts, they can easily land on air cargo containers, trains, ships, buses etc. Not called gypsy moth for nothing!

Asian gypsy moth eggs on military equipment coming from Germany to Ft. Benning, Georgia

The entire U.S. is continually monitored for the gypsy moth. Often one pheromone trap/4 sq. mi. along highways & a trap/1 sq. mi. in population centers.

Active gypsy moth tacking system in Canada also. Egg laying sites search Opened pheromone trap Pheromone traps at hwy. rest stops Objects around old barns searched for egg masses

When males are trapped the affected area is delimited: 1 st. 4 traps/sq.mi., then 8 traps and even 16 traps/sq.mi. When the source is found: The area (often a backyard) is treated with one or two Bt sprays.

When egg masses are found, three sprays of Bt bracket the emergence of the moths.

Life cycle of the gypsy moth

Lifecycle of the gypsy moth

Over the years many parasitoids and predators have been introduced from Europe to control the gypsy moth, only a few have become established. The Calosoma ground beetle is a good example.

The best natural control, however, is the Wipfelkrankheit that somehow was introduced from Germany in 1909.

Even though the gypsy moth is an exotic pest its main natural control did enter North America. It’s a NPV virus called (in English) the wilt disease. The NPV particles enters the larvae where the virus kills the insectan blood cells and the larvae seem to wilt.

Gypsy moth population Weather Hosts Site - soil - climate Competition - intra - inter Health of the population Virus epizootic Natural enemies Direct insolation

Big current problem is the potential establishment of the Asian variety of the gypsy moth.

Asian European And she flies! The two varieties of the gypsy moth

1992 Eradication program against the Asian gypsy moth

The Sawflies: Important Defoliators of Hardwoods and Conifers. Some Are Leafminers, Skeltonizers, but Most Are Leaf-chewers.

Sawfly defoliators are larvae of a group of primitive wasps, the Symphyta. Sawfly larvae look like caterpillars, but they aren’t. Caterpillars are Lepidoptera

Sawflies Caterpillars

More Sawflies

Oviposition of sawflies into pine needles

Sawfly larvae feeding on conifer foliage.

Feed in spring!

Feed in summer!

Sawfly defoliation of hybrid poplar plantation near Portland, OR.

Poplar sawfly pupa, new adult ovipositing and larvae devouring the foliage.

Adult in spring Sawfly larvae

Number of eggs per female = 63.74

Larval parasitoid Pupal parasitoid

My 1958 experience with the black-headed sawfly in East Texas.

1958 outbreak of the black- headed sawfly, Neodiprion exictans.

2,400 Acres (1) Raining frass and the foliage is thinning. (2) Aerial appraisal

Swamp Kirby Lmbr. Co. R.R. Skidway D4 Cocoons The great 1958 spraying operation directed by Bob G.

Loading DDT The Kirby skidway used as runway

Headquarters and radio Spray planes lining up on smoke

Smoke

Even though defoliators are beautiful we must move on to Barkbeetles