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Gypsy Moths ...

Gypsy Moth Threat, 2008 - 2009

Gone for now ... until the cycle begins again.

July 10, 2009: The following information is from Gypsy Moth News - July 2009 from the Centre County Gypsy Moth Program.

The Gypsy Moth has left the County (and State)
Most of you probably will not be surprised to hear that the Pennsylvania DCNR is finding that there has been a near-complete collapse of the gypsy moth population in the state. This is very much what many of you reported when you filled out the Gypsy Moth Activity Report on the county's gypsy moth web site. Many thanks for your efforts - and for your unique observations in the text box. Such surveys are extremely helpful in getting a big picture view of what is happening in our large county.

The general collapse occurred as a result of the extremely unseasonal rainy weather that the whole of Pennsylvania experienced during late May and June. On three separate occasions, stationary fronts parked themselves over the Ohio valley and poured rain on us for a whole week. These were very favorable conditions for the pathogenic fungus, Entomophaga maimaiga, to grow from strength to strength until it killed even strong, late-stage caterpillars all over the county.

Long-term Monitoring
During the current outbreak, many municipalities were subjected to a defoliation and Rush Township was subjected to two before any control measures were taken. The main reason that such delays occur is that during times of no gypsy moth activity, the county personnel used in monitoring gypsy moths are stood down and eventually reassigned to other duties, with only professional foresters (mostly DCNR state employees) left on watch. Even these foresters can be caught unawares, especially if a population build-up occurs seemingly out of synchrony with when it was expected to rise.

Although my contract with the county terminates at the end of July, I would like to set up a group of 'citizen entomologists' who would monitor the county for gypsy moths and would fill out online surveys each April (for young caterpillars) and September (for new egg masses). .

Of course as well as monitoring the gypsy moth situation, there will need to have an action plan on how to respond to any population build-up. It is likely that during the initial population build-up phase there may not be any state program or funding available for any local gypsy moth suppression programs. In such cases, any suppression measure would have to be handled at municipality or county level.

I will be contacting some of you who showed a keen interest in the gypsy moth situation over the last two years. I would like to get as complete a geographical coverage of the county as possible, so that we can monitor comprehensively.

Karl Mierzejewski
Gypsy Moth Coordinator

We want to thank everyone, especially College Township, who contributed time and money to the Conservancy in order to fight the impact of the Gypsy Month on the Mountain over the past two years. The Conservancy still needs your support though! Please help the Conservancy by becoming a Friend of Mt. Nittany


The Mountain sprayed on May 18, 2009

Helicopter spraying took place from first light until around 10 am according to the Centre County Gypsy Moth Program.


April 28, 2009: The following information is from Gypsy Moth News - April 2009 from the Centre County Gypsy Moth Program.

"Many of you may have noticed the emergence of tiny gypsy moth caterpillars from their egg masses last weekend. Over the next week to ten days, Centre County will be experiencing the dispersal of these caterpillars as they blow with the wind on fine silk threads. The little larvae are only interested in one objective - to get to a tree which has their favorite type of leaf (such as oak or apple) and start feeding.

Their appetites are miniscule at this stage and spraying them with Bt (the biological larvicide that DCNR uses) is not effective. Because they eat so little, the chances of them meeting a droplet of Bt on a leaf is small, plus they could exhibit avoidance behavior as they eat around the dried droplet, which appears very big to them. Another reason why spraying is inadvisable is the possibility of more gypsy moth being blown in from a different source which could arrive at a spray site where earlier-sprayed Bt has little activity left. (Bt is inactivated by ultra violet light and nearly all of its activity is gone a week after spraying.)

Spraying is most affective once the caterpillar has reached the second stage. It still has a small appetite, so the damage it can do is very small, yet it is still very sensitive to Bt and there is a good chance that it will eat a droplet of it in the course of its normal feeding.

Spraying: So when will it take place? The development of leaves and caterpillars is very much determined by the temperature. If this turns out to be a typical spring, then spraying will take place around Memorial Day.
"


April 20, 2009: Centre Daily Times article called "Gypsy moths back for another year" reported on the reemergance of Gypsy moths in the upcoming weeks..

"Property owners in the parts of Centre County still plagued by gypsy moths can expect to see the caterpillars emerging from egg masses in the coming weeks.

Centre County gypsy moth coordinator Karl Mierzejewski said the state’s spraying program will likely happen in mid-May. Landowners who aren’t covered by the program or who want to give the gypsy moths a double whammy can also buy a spraying kit from a garden store.

"Now is really the perfect time," Mierzejewski said.

Once the caterpillars hatch from their yellowish, quarter-sized masses, they fall to the ground on their threads and make their way up trees. The off-the- shelf spraying kits include burlap to wrap around the tree trunks that you spray with the insecticide.

Otherwise, Mierzejewski said, the caterpillars climb to the tree tops and wait until the leaves are big enough and they’re ready to start feeding.

He said he expects the gypsy moths will start hatching toward the end of April, although it could be earlier in warm, dry places.

Aerial spraying of a biological pesticide through the state Department of Conservation and Natural Resources could take place in mid-May, depending on how the foliage develops.

Which parts of the county will get sprayed has already been determined.

After blanketing parts of Centre County for several years, the gypsy moth population has collapsed in many places, but is still present in some areas.

Mierzejewski said his guess is that the infestation is ending, in keeping with the typical gypsy moth pattern of hitting an area for about three years before a population collapse.

"Pockets may need to be treated next year,” he said, "But it’s not going to be this area-wide
defoliation we had in 2007 and 2008."
"

PDF version


Jan 29, 2009: Centre Daily Times article called "Gypsy moth spraying set for county" reported on plans for 2009 spraying.

"Centre County and the state are preparing for gypsy moth spraying in parts of the county this spring, although less land will be covered than last year.

The Centre County Board of Commissioners voted Tuesday to approve an agreement with the state Department of Conservation and Natural Resources for the spray program. Director of Planning and Community Development Bob Jacobs said the $137,676 contract is for more than 6,000 acres at a cost of $21 an acre.

The money will come from residents whose land is being sprayed and municipalities.

Gypsy moth caterpillars eat the leaves off oaks and other trees which, over several years, can cause trees to die. The population of gypsy moths in Centre County has been collapsing, and program coordinator Karl Mierzejewski said he expects that will continue.

Last year's spraying took place at the end of May. The state contractors uses Bacillus thuringiensis or Bt, which only affects caterpillars in the larval stage that eat sprayed leaves."


Centre County Gypsy Moth News - The Big Picture

The following information is from Gypsy Moth News - October 2008 from the Centre County Gypsy Moth Program.

"Parts of Centre County have had gypsy moth outbreaks for three years in succession and residents have come to expect an onslaught in spring, which they hope will be mitigated as the helicopters of the state DCNR spray program fly overhead spraying their biological insecticide. So it is not surprising that the reaction of property owners in the County's western townships to the news that they will not need spraying is one of disbelief that things have returned to normal. In fact, this is the usual sequence of events in a gypsy moth outbreak.

When talking with federal and state insect pathologists, they point out that the environment for any gypsy moth caterpillars that manage to emerge is extremely hostile in areas that have been infested for three years in a row. All sizes of organisms are now after gypsy moths: microorganisms such as fungal and viral pathogens, parasitoids (parasitic insects that end up killing the host) and even predators like birds and rodents that have adapted their diet to include gypsy moths.

However it is the first category, pathogens, that led to the major population collapses that we witnessed at the end of the gypsy moth season this year in parts of the Centre Region and western townships. A USDA Forest Service program conducted in Centre County this year estimated that the Entomophaga fungus killed 80% of the gypsy moth population this year, and in concert with another pathogen, NPV virus, caused the population collapse where gypsy moth mortality was close to 100%.

However, Centre County is a large county, with three quarters of a million acres of forest. Such a large area does not behave uniformly to events like an insect infestation. Over the last three years we have seen a west-to-east progression of gypsy moths and this year it is the eastern townships which in 2009 will be experiencing their first or second gypsy moth outbreak."


Gypsy Moth Situation in Centre County - the next (2009) generation

The following information is from Gypsy Moth News - September 2008 from the Centre County Gypsy Moth Program. The arrow tag to Mt. Nittany was added by us.

"The map below shows the areas that are more likely to have infestations next year based on a month-long survey that I did in the county, counting new egg masses which develop into the next generation. The color ramp shows relative egg mass densities, with white indicating no egg masses (or very small numbers below the DCNR treatment threshold) and increasing redness showing increased egg mass densities. Because I was primarily surveying land parcels based on users' spray requests, the sampling was by no means evenly distributed across the county. The gray areas on the map indicate parts of the county which were not surveyed because there were no requests for spraying.

The main trend for next year is that the gypsy moths have moved east and south and have mostly left the western municipalities except for an area in south Taylor Township. So the ‘hot' areas next year will be in the eastern townships as well as southern ones which prior to 2008 had not experienced an outbreak. Clinton County, which borders Centre County's eastern boundary, will experience a major upsurge in population next year.

There are some small residual gypsy moth populations in areas previously infested in the Upper Bald Eagle Valley Region (Worth, Huston and Union Townships), many of which meet DCNR treatment thresholds of 250 egg masses/acre. Homeowners who have requested spraying will most likely be sprayed. However, it is my estimate that unless it is a very dry spring which aids the survival of caterpillars, many of the areas that have such low populations will not suffer any major defoliation next year if left unsprayed."


Gypsy moth on the Mountain - July 28, 2008

The following information is from Alan Cameron, MNC Board Member and Penn State Professor Emeritus of Entomology.

"Yesterday Jule and I took a look at the top of Mt. Nittany to see what is happening with respect to the gypsy moth. We did the white blazed trail only. I saw maybe as many as half a dozen females still laying eggs; few males were seen; flight is almost over.

The good news is that the spray job this year was, for the most part, very effective. Not only did trees not suffer defoliation, but gypsy moth larvae were killed. This was especially evident on the ascending trail from Mt. Nittany Road. We saw no new egg masses as we hiked, and there is only very light defoliation evident in a few places. On the top of the Mountain, however, the story is a little different. The area generally to the north-east of the eastern junction of the Blue blazed trail coming back from the Mt. Nittany School/Boalsburg viewpoint suffered moderate to heavy defoliation. [Standard definitions of defoliation levels are as follows: 'light' - <30% leaf surface lost; 'moderate' - 30 - 60% leaf surface lost; 'heavy' - >60% leaf surface area lost. Heavy defoliation normally triggers refoliation in August, an additional physiological drain on the tree.] This area suffered some of the heaviest defoliation on the mountain last year, and is the area in which I found the greatest numbers of egg masses last summer.

There is an area on the top of the Mountain (the moderate to heavy defoliation this year) where I expect to see additional tree mortality over the next few years. These trees were not especially healthy going into this summer, and I will be surprised to see at least some of them refoliate this year - they are essentially dead now but just don't know it. Some trees are obviously dead, and some of these should be dropped for public safety purposes. I saw a few dead larvae hanging in the typical posture that indicates that they died of the virus disease. That is good news. As reports become available on egg mass counts on neighboring ridges, we will be in better position to speculate on how much blow-in of dispersing larvae there may be next spring.

It surprised me at this time of year how many of the old egg masses remain. Over the next months, they will weather away, as should the old pupal cases. To the untrained observer, the very large numbers of old egg masses that persist could give a false sense of the potential for defoliation next year.

I have attached three photos from yesterday, all taken on the top of the Mountain in the area of greatest concern."

This image shows Moderate to Heavy Defoliation.

Gusey Moth - moderate to heavy defoliation.

This image shows Heavy Defoliation.

Gusey Moth - heavy defoliation

This image shows one new egg mass (the one that is reddish-brown) along with numbers of old (hatched; from 2007) egg masses and old (2007) pupal cases still remaining on the tree.

Gusey Moth - Egg Masses


The Mountain being sprayed May 15, 2008

Mt. Nittany being sprayed for Gypsy Moths on May 14, 2008. Photo by Ken Reeves, MNC Director Emeritus.


The following are additional links with information about the Gypsy Moths and their impact to the Mountain collected by the Conservancy since Fall 2007.

June 18, 2008: The Centre County Gypsy Moth Program website includes "2008 Gypsy Moth Outbreak: The Big Picture". This report says the following:

"Following a limited aerial survey on Sunday, June 15, it seems as if the ridges are receiving most of the damage as measured by defoliation. Bald Eagle / Purdue mountain and its continuation eastwards is being chewed up badly – it is looking browner each day. However, Mount Nittany is probably getting hammered the most. The areas that were sprayed are showing up dark green against the increasing brown, which is apparent as far east as my eye could see. The next ridge south, Tussey Mountain seems to paint a different picture; westwards there are signs of defoliation whereas eastwards all seems fine."

If you supported our spray efforts this spring, the Conservancy is very grateful for your help! As the County and DCNR discuss gypsy moth suppression program plans for 2009, we will be there to ensure that our Mountain is protected.

May 14, 2008: The Mountain was sprayed with the biological insecticide, Bacillus thuringiensis (Bt), comprised of naturally occurring Bacillus spores. No chemical insecticides were used. The Conservancy again thanks all our Friends that have supported us during of fund raising campaign for this spraying.

April 29, 2008: The Daily Collegian printed an article called "Moths to be sprayed." The article states in part: "Gypsy moths, which hatch in late spring, cause massive defoliation and can wipe out many of the mountain’s trees. If nothing is done by August, Mount Nittany will be leafless, Woodhead said."

April 23, 2008: The state Bureau of Forestry announced plans to triple its aerial spraying effort to suppress the woodland insect pest. See "DCNR to begin spraying woodlands to combat gypsy moth damage." The article states "Nine helicopters and five fixed-wing aircraft will begin the spray program in early May and end shortly after Memorial Day. Spraying is dependent on weather, foliage development and caterpillar development; progress can be tracked at www.dcnr.state.pa.us/forestry/spray.aspx."

April 3, 2008: Penn State's Daily Newswire had an article called "Gypsy moth management made more efficient, cost-effective."

Feb 25, 2008: WPSU's Pennsylvania Inside Out discussed the Gypsy Moth Threat (starts at 3:30). The segment featured Alan Cameron, Penn State Professor Emeritus of Entomology.
Watch: Pennsylvania Inside Out: This is THON, Gypsy Moth Threat, Koyannisqatsi

Nov 16, 2007: The Daily Collegian printed an article called "Conservancy prepares for gypsy moth damage by 'selling' Mt. Nittany." This article starts: "A menacing creature is lying in wait on the branches of trees lining Mount Nittany, and Penn State alumni could help fend it off."

Nov 6, 2007: Centre Daily Times article called "Gypsy moths threaten Mt. Nittany", the stage is set for heavy defoliation not only on top but also on the highly visible sides of our beloved Mountain in 2008.

Gypsy Moth Larva(e) E. Bradford Walker, Vermont Department of Forests, Parks and Recreation



Centre County Gypsy Moth Program: For more information on the Centre County Gypsy Moth Program, you can visit this website: http://www.co.centre.pa.us/gypsymoth/default.asp. Their site includes a link to Health Facts. Here they explain that the biological insecticide called B.t. or B.t.k for Bacillus thuringiensis var kurstaki will be used in the spraying program.

Centre County Township sites:
College Township
- Our Mountain Needs Us
Ferguson Township -
Gypsy Moth Spraying Information
Halfmoon Township - Gypsy Moths page
Patton Township -
Gypsy Moths page

Gypsy Moth Images: See the Gypsy Moth section of the Forestry Images website. Be sure to scroll down to the "damage" photos.

Copyright © 2005-2008  Mt. Nittany Conservancy.  All Rights Reserved.