Mating Disruption Treatments for Spongy Moth Scheduled for Ohio

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The Ohio Department of Agriculture (ODA) has scheduled mating disruption treatments in 9 Ohio counties to reduce spongy moth populations and slow the spread of this non-native invasive insect species. Treatments are scheduled for later this week, but timing will be weather dependant. 


The nine counties in this year's Slow-the-Spread Project include: Delaware, Guernsey, Knox, Licking, Morrow, Muskingum, Putnam, Vinton and Washington Counties. 


Below is an example of one of the maps for reference. This map is of the Guernsey County block, on the Guernsey / Noble County line. Check out the ODA website for the other maps.  All maps are avialble in both a PDF version like showing below, or in an online searchable version.


Guernsey County Treatment Block



Those nine counties that well be received a mating distribution treatment are part of the larger quarantine in Ohio that includes 51 of Ohio's 88 counties. A quartantine has been established in hopes to eliminate the spongy moth spread via artificial movement into new uninfested counties in Ohio, and ultimately states to the west. See the quarantine map below.  

Ohio Quarantine Spongy Moth Map


The spongy moth, Lymantria dispar, (formerly the European gypsy moth) is a non-native, invasive species that has moved west into Ohio from Pennsylvania and south from Michigan. Each egg mass a female lays can contains between 500-1,000 individual eggs; once hatched they are able to feed on the leaves of over 300 different tree and shrub species.


The photo below illustrates the first hatch of first instar caterpillars that occurred earlier this spring, about the same time as redbud trees are blooming. Since their arrival, they are leaf feeding machines. The bigger the caterpillar, the more they can consume. Oaks trees tend to be their favorites, but as the mature, the like seem to enjoy spruces as well. The feeding injury is especially hard on evergreens and I have observed spruces dying in a single season where nearly all the needle foliage was consumed. 



Egg Mass Taken In Early Spring as Caterpillars Begin to Hatch
Photo Credit: Amy Stone, OSU Extension - Lucas County


As the caterpillars grow, so does their appetite. One 2-inch larvae can consume up to 1 square foot of foliage every 24 hours. In heavily infested areas, where there are 250 or more egg masses per acre, the spongy moth is able to completely strip the infested trees. In addition to the feeding damage that can occur, what comes in - must go out. There have been reports from infested locations of 'raining frass' or the insect's excrement. It can make for an unenjoyable time outdoors for you and your trees.  


A healthy decidous tree can usually withstand only two years of defoliation before it is sent into decline, or even dies. 


Spongy Moth Caterpillar - A Caterpillar Eating Machine



After the caterpillars compete their feeding-frenzy, they will pupate and emerge as an adult moth. Female moths are white and are not capable of flying. The males are brown and flying in a zig zig pattern. The adults do not feed, therefore causing no additional damage to the plants. They do however want to find a mate so the female can lay an egg mass that will overwinter and hatch the following spring - and so the cycle continues. There is one generation in Ohio per year. 


The purpose of the mating disruption is to confuse the male moth by saturating an area with a phermone-scent that is normally given off by a female spongy moth looking for a mate. Since the 'smell' is everywhere, he is not able to actually find her, thus can't mate, her eggs don't get fertilized, and the cycle is disrupted. This form of treatment is used when populations are still relatively low, with the goal to reduced their numbers even futher into the future - slowing the natural spread of the spongy moth. 


If you suspect you see spongy moth caterpillars now, you are asked to report that using the Great Lakes Early Detection Network App ( ), or contacting your local Extension office ( ) or the Ohio Department of Agriculture ( ).