Pros and Cons of Different Methods to Control the Spread of Gypsy Moths

Taken from the Yellow Springs Tree Committee Presentation April 11, 2001




1. BTk is a naturally occurring, soil dwelling bacterium
2. BTk and its toxins are killed within three to five days by sun and other microbes although spores of BTk may remain in the soil for a few days to weeks.
3. BTk is not active in the soil and is not absorbed from the soil by plants.
4. The EPA concludes that BTk is not a risk to groundwater.
5. The active ingredients in BTk do not evaporate into the air.
6. BTk is harmless to mammals


1. Harmless butterflies and moths are also at risk from ingestion of BTk.
2. Timing of application is critical. Only young caterpillars have guts thin enough for BTk to punch holes in them. For Gypsy Moth, once the larvae have gotten larger than 5/8", they become difficult to kill with BTk. BTk must be applied after eggs have hatched but before the caterpillar have reached the third instar. 



1. Very effective in reducing populations of gypsy moths in areas of both high or low levels of infestation.
2. It is a common disease in the gypsy moth that kills large numbers of larvae.
3. It is established in a large area of the North-East and is considered a major factor in controlling the population density of the Gypsy Moth.
4. It may be responsible for reductions attributed to other control measures
5. Naturally wind born or tracked to new areas.
6. Distribution by state and federal agencies has supplemented the natural spread of the fungus
7. Usually no charge to the local area.
8. It is not known to pose health risks to people or pets. 
9. No threat to other life forms other than a tobacco hookworm and the Douglas fir tussock moth.


1. Needs moisture to germinate and hatch.
2. Natural distribution of Em lags the spread of the gypsy moth
3. Other natural enemies (virus, dear mice, stinkbugs, and birds) may account for some of the kills attributed to Em
4. Difficult to measure effectiveness as control plots are difficult to keep uncontaminated. 
5. Other management techniques are needed in many cases.
6. Takes 2-4 years to establish itself naturally, so the initial outbreak will have already occurred which causes much of the tree mortality.
7. Even the infected caterpillars will continue to defoliate the trees for up to 10 days. 
8. There is no commercial distribution of Em
9. Difficult and expensive to produce in the laboratory and to distribute effectively. 
10. One paper stated the usual disclaimer: Artificial inoculation of Em into areas without the gypsy moth but where an infestation is anticipated is not recommended due to lack of sufficient research. 



1. There is no evidence of health problems related to pheromone dispersal
2. The pheromone treatment has a high rate of success
3. It is cost effective (i.e. it will cost the Yellow Springs nothing)
4. If nothing else it will buy some time and hopefully prevent a large infestation
5. Treatment does not need to be repeated annually 


1. Potential damage from the plastic flakes (1/32"x3/32", 1cup per acre). Currently research is being done on developing a biodegradable flake.
2. Some people are uncomfortable because of the "no information available" in areas such as chronic toxicity on the Disparlure Fact Sheet (5) This is addressed in the Porter County Environmental Assessment report where they state "The toxicity of insect pheromones to mammals is relatively low and their activity is target specific. Therefore the EPA requires less rigorous testing of these products than conventional pesticides."(6)



1. Natural to the environment
2. Species specific - not harmful to non-target organisms
3. Works well in moderate to heavy gypsy moth densities
4. Remains in the environment to help 'trigger' future outbreaks


1. Cost
2. Not as effective in low density gypsy moth populations
3. Research is still being done to refine application amounts 



1. Not using a chemically manufactured product


1. No information given regarding the dangers of the wasp itself
2. No assurance that the wasps are gypsy moth specific
3. Treatment must be done annually
4. Cost--approximately 4,500 per year
5. Release of the wasp must be accompanied by the mechanical removal of the Gypsy Moth larva and caterpillars using forceps or gloves
6. The total process is very time and labor intensive
7. Success depends on the involvement of a great number of citizens in the community.
We have many public areas such as Mills Lawn, Antioch College Campus, Gaunt Park, Ellis Pond Park, and Bryan Center Grounds that will need to be taken care of.