Browntail Moth and the Big Itch: Public Health Implications and Management of an Invasive Species

Home , Compsilura concinnata, Dorsum (moth), Imago

July 22, 2021

Jill H. Colvin, MD, FAAD MDFMR Dermatology

photo credits: Jon Karnes, MD Thomas E. Klepach, PhD Assistant Professor of Biology, Colby College Ward 3 City Councilor, Waterville, Maine Financial disclosure statement

Jill H Colvin MD and Thomas E. Klepach, PhD do not have a financial interest/arrangement or affiliation with any organizations that could be perceived as a conflict of interest in the context of this presentation. OBJECTIVES

• Identify: • Impacts of browntail moth (BTM) infestation on humans and the environment • Review: • Presentation and treatment of BTM dermatoses • Biology of the BTM • Population trends of the BTM • BTM mitigation strategies JUNE 2021, AUGUSTA, MAINE PERVASIVE! COMPLICATIONS OF INVASIVE BROWNTAIL MOTH

SOCIAL MEDIA RADIO

ARBORISTS PHARMACY

NEWSPAPERS FRIENDS

COLLEAGUES HEALTH CARE

FAMILY TEXTS

TOURISM PATIENTS MAINE.GOV SELF REALTY PHONE CALLS ACTIVISM TREES SOCIAL MEDIA

IMPACT: TOURISM, REAL ESTATE, DAILY LIFE Maine.gov

Maine.gov

Photo credit: Jon Karnes, MD Photo credit: Robert Kenney, DO BTM: Risk to Human Health

Mediated by: Toxic hairs on caterpillars, female moths, environment Direct contact Airborne

Damage skin, eye, airway in multiple ways Mechanical: Barbs on hair Chemical: toxin Irritant Allergen

One report of Death – 1914: ”severe internal poisoning caused by inhaling the hairs” Definitions

Lepidopterism is the term for cutaneous and systemic reactions that result from contact with larvae (ie, caterpillars) or adult forms of moths and butterflies (order, Lepidoptera).

Erucism (from Latin "eruca," caterpillar) is also used to refer to reactions from contact with caterpillars.

photo credit: Jon Karnes, MD “The BTM, its caterpillar and their rash” Clinical and Experimental Dermatology (1979), Cicely P. Blair, Oldchurch Hospital, Essex, England

36 patients, 4 – 76 years old • “Not all patients knew they had been in contact w/ caterpillars but knew that there were caterpillars in vicinity.” • The vicinities were examined to confirm presence.

Interval between exposure and symptoms: 8 – 12 hours • Except for one patient w/“blotchy erythema” few minutes post exposure

Symptoms: itching > > soreness • peaks during first 24 hours, resolves over 10 days

Associated findings: • Conjunctivitis (2 patients) resolved within 5 weeks • Malaise thought due to antihistamines or lack of sleep (3 patients) Photo credit: Jon Karnes, MD • Rhinitis ? Due to seasonal allergies as prick test was negative to caterpillar molt (1 patient) • Dry cough x 1 week coincidental with rash (1 patient) • Secondary impetigo (1 patient) BTM Rash: • Neck, wrists and forearms > other noncovered areas • Day 1 – 3: 3 – 5 mm red maculo-papules which may be tinged with orange centrally • Sometimes had vesicle or pustule • Lesions were larger and could be linear if direct caterpillar contact occurred • Resolved within 10 days • Though can last longer, typically via re-exposure. • “One patient and the eruption for 4 months and had burned his duvet and was on the point of destroying his Siamese cat before establishing BTM as etiology.”

Photo credit: Jon Karnes, MD Investigative Studies of the Dermatitis Caused by the Larva of the BTM Arch. Derm. Res. (1976) deJong, et. al., Dept. Derm., State University Groningen (The Netherlands) Hypothesis: Inflammatory reactions due to at least two effects • Mechanical trauma from the barbed setae (hairs) • Toxic actions of water-soluble substances associated with setae

Histopathology of skin after nettling hairs into skin (39 biopsies) • Untreated hairs > trauma to skin than heat treated hairs

Scanning Electron Microscopy of Setae (hairs) • Tapering hollow microcapillaries which are open at both ends • May serve as microneedles which liberate irritant substances • Mechanical and toxic effects

Caterpillars and Moths Dermatologic Therapy, 2009 Eric W. Hossler, Dept. Derm. Geisinger Medical Center, Danville, PA “Therapy remains largely empiric; to my knowledge there have been no controlled therapeutic trials for lepidopterism.” • “Home remedies can help with symptoms.” • RX approaches for BTM contact dermatitis can help, but not as reliably as we expect for classic allergic contact dermatitis • Topical steroids • Prednisone tapers Treatment Strategies Remove offending hairs from skin • Duct tape or other adhesive • Immediate washing with soap and water • Shower not tub bath • Change and launder clothing • Remove jewelry and watches in anticipation of swelling Relieve symptoms of itch • Camphor, menthol, pramoxine, cool packs, witch hazel, topical diphenhydramine Reduce inflammatory reaction • Topical steroids • Systemic steroids • prednisone 1 mg/kg/day tapered over 2 – 3 weeks • IM Triamcinolone 40 mg • Systemic antihistamines: variably helpful • Topical aspirin reduced histamine induced itch in one study

Prevention/avoiding exposure • Protective clothing, mask, do yard work on wet days • Dry clothes inside not outside on a line

If you are having trouble breathing, swallowing, or have swelling of your mouth tongue, or throat, call 911.

RareRare systemicsystemic riskrisk fromfrom BTM:BTM: PulmonaryPulmonary ? AnaphylacticAnaphylactic OneOne reportedreported deathdeath inin thethe earlyearly 1900s1900s afterafter BTMBTM setaesetae inhalationinhalation

Photo credit: Jon Karnes, MD State Resources

• Maine.gov • 211, text 898211

• ME Dept. of Agriculture, Conservation and Forestry ME Forest Service Entomologists + U Maine Track spread Investigate causes Evaluate management strategies https://www.centralmaine.com/2021/06/02/waterville-council-exploring-ways-to-mitigate-browntail-moth-infestation-in-the-city/ Browntail Moth: Public Health implications & Management Dr. Thomas Klepach, PhD, Assistant Professor Biology Department Colby College, Waterville City Council Ward 3 Representative

Seals of The City of Waterville and Colby University in 1896 when BTM Were First Reported in the US Browntail Moth: Public Health implications & Management Dr. Thomas Klepach, PhD, Assistant Professor Biology Department Colby College, Waterville City Council Ward 3 Representative

Objectives: • Biology • Pathogenesis • History • Causative and Mitigating Factors in Outbreaks • Management Strategies & Policy Recommendations Euproctis: genus of >650 named moths native to eastern hemisphere 1. E. similis - Goldtail moth or Swan moth (Eurasia, Ural Mountains etc.) 2. E. edwardsi – Mistletoe browntail moth (Australia) A half dozen species 3. E. bipunctapex –Tussock moth (Singapore, Thailand) from this genus are a 4. E. flava – Asian mulberry tussock moth (Japan, China) health hazard to 5. E. pseudoconspersa – Japanese tea tussock moth (Japan) humans and animals.

1 2 3 4 5 Euproctis: genus of >650 named moths native to eastern hemisphere 1. E. similis - Goldtail moth or Swan moth (Eurasia, Ural Mountains etc.) 2. E. edwardsi – Mistletoe browntail moth (Australia) A half dozen species 3. E. bipunctapex –Tussock moth (Singapore, Thailand) from this genus are a 4. E. flava – Asian mulberry tussock moth (Japan, China) health hazard to 5. E. pseudoconspersa – Japanese tea tussock moth (Japan) humans and animals.

1 2 3 4 5

Part of the family Lymantriidae that includes the gypsy moth (Lymantria dispar), another non-native urticarial moth. Euproctis: genus of >650 named moths native to eastern hemisphere 1. E. similis - Goldtail moth or Swan moth (Eurasia, Ural Mountains etc.) 2. E. edwardsi – Mistletoe browntail moth (Australia) A half dozen species 3. E. bipunctapex –Tussock moth (Singapore, Thailand) from this genus are a 4. E. flava – Asian mulberry tussock moth (Japan, China) health hazard to 5. E. pseudoconspersa – Japanese tea tussock moth (Japan) humans and animals.

1 2 3 4 5

6. E. chrysorrhea – European browntail moth (Eurasia, Maine)

Ecologically unannealed xenobiotic species with few native biological controls that poses a direct human health threat. 6 Female Brown-tail Moth (Euproctis chrysorrhoea)

Alvesgaspar, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=5027960 Brown-tail Moth Life Cycle

Diapausal Overview: Terminology larvae (nesting)

 Larvae – caterpillars  Pupae – cocoon phase  Imago – adult moth  Diapause – nesting caterpillars  Gregarious – feeding together  Dispersive – feeding separately  Instar – larval moult  Setae – invertebrate “hair” Brown-tail Moth Life Cycle

Diapausal  E. Chrysorrhoea spends 9 months in a larvae (nesting) larval (caterpillar) form. Brown-tail Moth Life Cycle

Diapausal  E. Chrysorrhoea spends 9 months in a larvae (nesting) larval (caterpillar) form.  Only 3 feeding months in Maine. Brown-tail Moth Life Cycle

Diapausal  E. Chrysorrhoea spends 9 months in a larvae (nesting) larval (caterpillar) form.  Only 3 feeding months in Maine.  Peak hair exposure is in late spring and summer Brown-tail Moth Life Cycle Egg Female Brown-tail Moth oviposting. The eggs are hidden under the brown, felt-like covering.

Aug. – Sept. Egg masses contain 200 to 400 eggs. When the larvae hatch they feed for a short time before building their winter nests

Prefer non-current-year-defoliated trees for laying eggs. Brown-tail Moth Life Cycle Egg Brown-tail moth egg mass develops over roughly 1 month.

Aug. – Sept. Egg masses contain 200 to 400 eggs. When the larvae hatch they feed for a short time before building their winter nests Brown-tail Moth Life Cycle Egg Brown-tail moth caterpillars emerging from the egg mass.

Aug. – Sept. Egg masses contain 200 to 400 eggs. When the larvae hatch they feed for a short time before building their winter nests Brown-tail Moth Life Cycle Egg Larva First instar neonate caterpillars of (5 Moults) the brown tail moth on their egg mass.

Aug. – Sept. Sept. – June Egg masses contain 200 Nesting: Oct. – April to 400 eggs. When the Nests contain 25 to 400 larvae hatch they feed for larvae which emerged in a short time before spring to feed a new building their winter nests spring leaves. Brown-tail Moth Life Cycle Early instar caterpillars skeletonizing the leaf of an apple (Malus) tree. Side by side feeding is a common habit of social caterpillars. Brown-tail Moth Life Cycle: Preferred Food Sources They use these same trees to create their overwintering webs upon. • Also can eat birch, maple, and other hardwoods and shrubs.

Cherry Apple Hawthorn Pin Oak Red Oak White Oak Burr Oak Brown-tail Moth Life Cycle Early and Mid Instar The small caterpillars spin silk as they feed and rest under the material when they are not feeding. These early webs are added to and eventually become nests on which the colonies aggregate. Second Instar Third Instar

The nest faciliates thermoregulation Brown-tail Moth Life Cycle Fall nests (hibernacula) in which the caterpillars overwinter in diapause. • (25 – 400 larvae / nest)

Fernald and Kirkland (1903) found a mean of 290 caterpillar per web but up to as many as 802 showing the colonies originating from separate egg masses may fuse. Brown-tail Moth Life Cycle Egg Larva Late instar caterpillar dorsum, (5 Moults) showing two red dots near tail

Aug. – Sept. Sept. – June Egg masses contain 200 Nesting: Oct. – April to 400 eggs. When the Nests contain 25 to 400 larvae hatch they feed for larvae which emerged in a short time before spring to feed a new building their winter nests spring leaves. Final instar (Spring), lateral view They make cocoons in Brown-tail Moth Life Cycle leaves, on branches, Egg Larva Pupa on buildings, under eaves and boats (5 Moults)

Aug. – Sept. Sept. – June June – July Egg masses contain 200 Nesting: Oct. – April After defoliating trees, to 400 eggs. When the Nests contain 25 to 400 the last instar larvae spin larvae hatch they feed for larvae which emerged in cocoons in which to a short time before spring to feed a new pupate. building their winter nests spring leaves. The cocoons are full of toxic hairs.

Photo: Midcoast Maine Browntail Moth Support Facebook Brown-tail Moth Life Cycle Egg Larva Pupa Imago (5 Moults) (Adult)

Aug. – Sept. Sept. – June June – July July – Aug. Egg masses contain 200 Nesting: Oct. – April After defoliating trees, Moths emerge from their to 400 eggs. When the Nests contain 25 to 400 the last instar larvae spin cocoons, meet, and lay larvae hatch they feed for larvae which emerged in cocoons in which to eggs on the underside of a short time before spring to feed a new pupate. leaves. More hair is shed building their winter nests spring leaves. The cocoons are full of to cover the egg mass toxic hairs. Dorsal Ventral

Female

Male

By Didier Descouens - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=31361057 Dorsal Ventral

Mitigation efforts against adults must target females to be effective Female BTM Imago Artificial lighting congregates Euproctis exacerbating outbreaks

July 3, 2021

• Flight activity peaks b/w 10pm and Midnight. • Males tend to be more July 2, 2021 attracted to lights. Artificial lighting congregates Euproctis exacerbating outbreaks

July 10, 2021 July 11, 2021

But females can New infestations anecdotally tied to locations with high also localize to populations (e.g. Eddington, Old Town, Burnham, Augusta, lighting fixtures. Waterville) – Artificial lighting? Brown-tail Moth Life Cycle Egg Larva Pupa Imago (5 Moults) (Adult)

Late Summer: April – July: Large amount of hairs in Large amount of hair activity / shedding. leaves and brush Hairs persist in environment for 3 years

Brown-tail Moth Dermatosis Pathogenesis

Setae (0.15 mm long) either true hairs or tubular SEM of surface of a seta showing spines and coalescing rounded Friable setae carried in air, settle on grass, leaves, brush, in lacunae. (x5400). yards, on porches, etc. Setae can be resuspended and contaminate clothing distal hung near affected trees

proximal

Arch. Derm. Res. (1975) 253, 287--300 Brown-tail Moth Dermatosis Pathogenesis

Tubular Setae TEM of a seta showing tubular structure and surface pits. (x.5380) • Tapering, hollow micro-capillaries • Open at both ends • Communicates with a poison-secreting gland • Inject toxins into skin and lungs. Toxins last 1-3 years in environment. • 2-5 % w/w Soluble protein with esterase, protease, and phospholipase activity. • 2 esterases at 27kD and 44kD • 0.01-0.05% w/w of histamine • Soybean trypsin inhibitor inactivates the esterolytic activity – treatment? • Arch. Derm. Res. (1975) 253, 287--300 Elicits IgG antibodies in rabbits. Dermatologic Therapy, (2009), Vol. 22, 353–366 British Journal of Ophthalmology, (1984),68,284-288 Setae Extracts Exhibit Trypsin and Chemotrypsin Like Protease Activity • Esterase / protease activity is extremely stable – hairs persist in environment 3yrs

Hydrolysis of 3 synthetic ester substrates by a constant Stability of the esterolytic activity at pH 8.0 and amount of non-lyophilized setae extract 37° C) of setae extract during16 days storage at

varying pH's and temperatures

C C

activity at at activity

pH 8.0 and 37 and 8.0 pH

sterolytic E

(Arginine ethyl and methyl esters) Arch. Derm. Res. (1977) 259, 247-262 Setae Protease and Esterase Activity is Susceptible to Inhibition • Esterolytic activity in the hydrolysis of BAEe was strongly inhibited by soybean trypsin inhibitor. • SERine Protease INhibitor (SERPIN) Superfamily. • 18.9% of the protein in a lyophilisate of water in which seeds were incubated for 24 hours. (easy to isolate) • Possible treatment for acute exposure?

Archetypical Protease

Covalent Adduct

Arch. Derm. Res. (1977) 259, 247-262 SBTI SERPIN Michaelis-Menten Plant Physiol. (1978) 61, 1, 30–34 Complex Front. Med., 12 February 2019 - https://doi.org/10.3389/fmed.2019.00025 Brown-tail Moth Dermatosis Pathogenesis

Setae penetrate skin unidirectionally and are prevented from removal due to barbs. Brown-tail Moth Dermatosis Pathogenesis

Setae cause physical damage and irritation. Brown-tail Moth Dermatosis Pathogenesis

Setae also release inflammatory toxins that cause irritation leading to mechanical disturbance and itching which can drive setae deeper Brown-tail Moth Dermatosis Pathogenesis

Edema compresses setae driving it even deeper into the skin. Brown-tail Moth Dermatosis Pathogenesis

If sticky tape is applied as soon as there is signs of exposure and quickly removed, it can remove the setae and limit the reaction.

“Is there anything that duct tape can’t fix?” Ophthalmia nodosa secondary to intraocular caterpillar hairs

• Inflammatory nodular conjunctival reaction precipitated by lepidopteran hairs. • Patients display conjunctivitis and uveitis.

Multiple hairs embedded in the peripheral cornea Two intraocular hairs in the anterior chamber of 2- surrounded by mild stromal haze (long arrows). year old girl Multiple exposed subconjunctival hairs and diffuse conjunctival injection (short arrows) as well as two hairs embedded at the lid margin Saudi J Ophthalmol (2020); 34:230-2 Ophthalmia nodosa secondary to intraocular caterpillar hairs

• Successful treatment requires removal of all setae from the affected area and ascertain any intraocular penetration or inflammation.

• Patients require continuous long-term follow- up as the setae may initially be masked by inflammation and are likely to migrate within the eye, causing significant risk of serious damage.

Intraoperative extraction of the anterior chamber hairs using intraocular forceps.

Saudi J Ophthalmol (2020); 34:230-2 History: Accidental Introduction to New England

• Imported to Somerville, MA on roses, in the late 1800’s.

• Came to the attention of the public when it achieved outbreak proportions in 1897.

• Population retreated to a few islands in Casco Bay, ME, and Cape Cod, MA

• Periodic outbreaks over next 60+ years

P. W. Schaefer, 1974 PhD Dissertation Population Ecology of the Browntail Moth in North America Account of a Local Resident:

“In the summer of 1896 I first noticed the brown-tail moth on my premises. The caterpillars did not do any particular damage that year, though they came out thick. In 1897 the caterpillars came out in such numbers they destroyed everything. I did not take any special pains to get rid of them until after they had eaten up everything. We had no fruit that year, and we have had none in 1898. While feeding, the caterpillars would devour leaves, fruit, buds and all. In 1896 only one small tree was attacked the next year they attacked the cherry, elm, pear and apple trees. They came into the house; the walks and fences were also covered with them. For three or four days I went out every morning and swept them off the planks. Last winter I cut off all the tents, so that we did not have any this year. Generally speaking, my neighbors took care of their trees, though there were a few who did not.” Federal Government Imposed Quarantine Maximum Extent: 1914

1922

Introduction in 1890’s

Published July 1, 1916 Maine Forest Service Aerial Survey: • Most Recent Outbreak in 2015 • Statewide problem by 2017

Adult moths picked up in light traps July 2017 Guidance from Past BTM Outbreaks? Annual Reports to Waterville City Council 1910-1920

Browntail moth winter webs collected for the public bounty. Photo from 1910 USDA Bulletin: “Report on the Field Work Against the Gipsy Moth and the Brown-Tail Moth” Report of the Street Commissioner, Feb 3, 1915 to the honorable mayor and City Council of the City of Waterville. The work of cleaning the city trees of brown tail moth was turned over to me to finish. This work when taken by me was in a very complicated condition and I found the territory which had been gone over had to be once again on account of doing part of the trees on the street and yet leaving others. I finished the work and think that I covered all of the city streets in a thorough manner.

Respectfully submitted, T.A. O’Donnell, Street Commissioner Report of the Street Commissioner, Feb 1, 1916 to the honorable mayor and City Council of the City of Waterville. The shade trees on a number of streets were in a dangerous condition, and I have removed a number of trees that were not safe, and also removed all decayed branches on others. The work should be given more attention and a lot of trimming done this spring.

Respectfully submitted, T.A. O’Donnell, Street Commissioner Pupils of Farm School, Thompson’s Island, destroying winter webs of brown-tail moth’s, December 1902. Report of the Street Commissioner, Feb 1, 1917 to the honorable mayor and city Council of the city of Waterville. At the first of the year we had a crew of men taking browntail moths off the trees. As soon as we finished clearing the trees of moths, we had a large crew of men trimming trees. We trimmed most of the trees in the City which cost nearly five hundred dollars ($500.00).

Respectfully submitted, T.A. O’Donnell, Street Commissioner

A series of cold wet springs and the introduction of a parasitic fly ended the outbreak in 1922. 1 Cooler Moister Spring Encourages Fungal Growth

Entomophaga aulicae vs. Euproctis chrysorrhoea

1. Normal late instar browntail moth caterpillar. 2a. E. aulicae infected browntail moth caterpillar, with 2b. increased magnification to highlight individual fungal hyphae on the surface of the integument, Photo: K. Boyd

2a 2b Biologic Controls Parasitic fly introduced c1906 against Lymantria dispar (Gypsy moths).

• Not species-specific: impacted many native moth and Compsilura concinnata butterfly species. • Extremely effective against Brown-tail moths. • BTM over-winter as caterpillars, which are what the fly larvae live within. • BTM extirpated by 1930s except off the coast of Maine, and tip of Cape Cod. • Reemergence of BTM around 2000 in increasingly large numbers in southern coastal Maine, from Portland to Bar Harbor. • Hyperparasitoids of the C. concinnata fly by a Trigonalid Monodontomerus aerus wasp, Monodontomerus aerus Ecology, (2006), 87(, 10, 2664–2672 Biologic Controls: BTM Research Group at U. Maine, Orono In NE, 9 native parasites, one fungi, and one virus previously reported. Pupation nests monitored for moths, parasitoids, and fungi, 2016 – 2019. • Adult parasitoids attack BTM, lay their eggs in BTM eggs, caterpillars, or pupae. • Their larvae feed on the developing browntail and the next generation adults emerge from the host, killing them in the process. Rearing containers of browntail moth pupae in 2018.

2016 – 2018 the most prevalent primary parasitoid reared Dr. Eleanor Groden Browntail Moth Research at U. Maine Orono from BTM pupae was Townsendiellomyia nidicola, a parasitic A Report of Activities and Findings 2016-2020, fly that specializes on BTM. (2021) Dr. Eleanor Groden Biologic Controls: BTM Research Group at U. Maine, Orono Hyperparasitism Reduces Effect of Primary Parasites Effect of Parasitism Mitigated by Hyperparasitism • Hyperparasitoid wasps also increased in their abundance in browntail moth pupae. • Hyperparasitoids feed on the primary parasitoids, and hence reduce the success of other parasitoids, like T. nidicola.

“Although parasitism may control some insect populations, we do not believe that parasitoids are causing enough mortality to naturally control populations, likely a result of many generalist parasitoids and high rates of hyperparasitism.”

Big problem for Waterville.

Browntail Moth Research at U. Maine Orono A Report of Activities and Findings 2016-2020, (2021) Dr. Eleanor Groden BTM Lifecycle Climate Effects: Maine, 1920

Diapausal larvae (nesting)

(Maynard Historical Society) Maynard’s MA Moth Department crew and wagon, circa 1910. • Ladders were used to get to higher parts of trees. • Toxic chemicals (PbHAsO4) were sprayed from pipes.

Burgess, A. F., and S. Crossman. 1929 USDA Technical Bulletin 86, Washington, DC, USA BTM Lifecycle Climate Effects: Maine, 2020

Diapausal Maine larvae (nesting)

Change in life cycle in Maine correlates with regional climate change trends.

https://statesummaries.ncics.org/chapter/me/ BTM Lifecycle Climate Effects: Maine, 2020

Diapausal Maine larvae (nesting)

Change in life cycle in Maine correlates with regional climate change trends. 2021 first eggs laid 2021 eclosion or emergence of imago https://statesummaries.ncics.org/chapter/me/ BTM Lifecycle: Valencia, Spain 2010

Native habitat: warmer / more arid Post- diapausal • Comparatively short diapause and more time gregarious larvae feeding as larvae.

• More robust, fecund, and less susceptible to Diapausal larvae (nesting) Post- pathogens. diapausal dispersive larvae

Eggs

Ecological Entomology (2011), 36, 188–199 BTM Lifecycle: Valencia, Spain 2010 Other Conclusions Different sources of BTM mortality as a • Outbreaks are more likely in coastal habitats where function of coastal vs. inland habitat higher mortality was compensated by higher reproductive potential.

• Residual mortality (i.e. not associated to any specific mortality agent like a parasite or predator) was positively and non-linearly related to population density.

• Outbreaks are intra-specially self-limited dependent on competitive population density.

• Weather conditions are a mitigating factor.

Ecological Entomology (2011), 36, 188–199 BTM Lifecycle: Climate Trends Favor More Outbreaks

°C mm °C mm 30 2020 Weather, Waterville, ME 120 35 2020 Weather, Valencia, SP 70 25 105 30 60

20 90 25 50

15 75 20 40

10 60 15 30

5 10

0 DL 5 PoDGL

–5 0 DL PoDDL –10 E PrDL P I P E I

• Larvae in Maine spend at least half the year in diapause. • Comparatively short time feeding and storing energy. • Greater rainfall and and cooler weather in spring promote growth of Entomophaga aulicae (parasitic fungus) – potentially less common. BTM Lifecycle Climate Effects: Increasing Precipitation in Maine

• Increased precipitation in Maine is primarily due to episodic extremes, however. • Precipitation events may not be useful in limiting BTM outbreaks

https://statesummaries.ncics.org/chapter/me/ Waterville, April 2019 Waterville, April 2020

Central Maine experienced 2 consecutive springs of drier weather relative to the southern coast leading to an outbreak.

Portland, April 2019 Portland, April 2020 Current Outbreak in Central Maine Current Outbreak in Central Maine Current Outbreak in Central Maine Current Outbreak in Central Maine Current Outbreak in Central Maine Maine DACF BTM Surveys 2020 / 2021

https://www.maine.gov/dacf/m fs/forest_health/invasive_threa ts/browntail_moth_info.htm Maine DACF Spatial distribution increased dramatically from 2020 – 2021: BTM Surveys • Environmental conditions: dry/warm spring. 2020 / 2021 • Lack of coordinated response partially as result of pandemic. • A regional problem requires a regional response. • Municipal and state level action.

https://www.maine.gov/dacf/m fs/forest_health/invasive_threa ts/browntail_moth_info.htm BTM Mitigation Strategies: Annual Cycle – Must Plan Success

Winter Feeding Feeding Larvae Pupae Imago Eggs Nests Larvae Oct – April April – June June – July July – Aug July – Aug Aug – Sept June – July:  Secure adequate funding in municipal budget. • Waterville: I recommend $50k / year to start.  Develop regional strategy. DL • Coordinate with surrounding municipalities.  Public education – signage, social media, etc. E September: I P  File Public Health Nuisance Declaration with Maine CDC. BTM Mitigation Strategies: Prevention & Public Education First-line management of exposure is prevention. • Don’t handle unknown caterpillars w/ hairs or spines (especially branched spines). • During heavy caterpillar outbreak, the sensitive should avoid infested areas. • Use long sleeve clothing, pants, gloves, mask if working around BTM (PPP). • Wet work areas down proximal to infested trees. • DO NOT PARK under/near infested trees! • Check that you do not move larvae, cocoons, moths • Use extreme care when removing caterpillars from skin or clothing to avoid dislodging setae or spines. • Use a wet/dry vacuum with a HEPA filter filled with a few inches of soapy water to suck up larvae. • https://www.maine.gov/dacf/mfs/forest_health/invasive_th reats/browntail_moth_faqs.htm BTM Mitigation Strategies: Annual Cycle – Must Plan Success

Winter Feeding Feeding Larvae Pupae Imago Eggs Nests Larvae Oct – April April – June June – July July – Aug July – Aug Aug – Sept September – November Increasing Exposure Risk for Hairs  Survey local infestation after leaves have dropped November – March  Clip and Destroy Accessible Webs Manually DL  Plan Spring Insecticide Treatment Late March – April E  Tree insecticide injections of trees with inaccessible webs I P • Use on public and and private (with permission) property BTM Mitigation Strategies: Tree Injection

Insecticide injected beneath the bark of the tree. Manual removal, is dangerous, very The insecticides move through the veins of the tree with expensive, and often not possible. sap and concentrate in the tree's leaves.

Benefits: • Targeted exclusively to feeding caterpillars. • No exposure for non-targeted organisms, wildlife, and people. • Low-level of material for effective results. • Treatment occurs right before budding and the caterpillars become active until pupation. • Treatment is completely safe for trees. • Treatment is easily contained.

https://www.pinestatepest.com/pest-identification/profile/browntail-moths BTM Mitigation Strategies: Annual Cycle – Must Plan Success

Winter Feeding Feeding Larvae Pupae Imago Eggs Nests Larvae Oct – April April – June June – July July – Aug July – Aug Aug – Sept April – May Increasing Exposure Risk for Hairs  Use base and canopy sprays (public / private). • Organics like spinosad / BT kurstaki.  Adhere to state DEP regulations around use of sprays near DL waterways.  Treatment after June is of limited value due to dispersive larvae and E pupation. I P  Use Personal Protection Precautions. BTM Mitigation Strategies: Annual Cycle – Must Plan Success

Winter Feeding Feeding Larvae Pupae Imago Eggs Nests Larvae Oct – April April – June June – July July – Aug July – Aug Aug – Sept June – July Increasing Exposure Risk for Hairs  Use Personal Protection Precautions.  Removal of accessible pupae with HEPA system.  Assess municipal budgetary need for coming year. DL

The problem is the worst when it is the most difficult to address E I P BTM Mitigation Strategies: Annual Cycle – Must Plan Success

Winter Feeding Feeding Larvae Pupae Imago Eggs Nests Larvae Oct – April April – June June – July July – Aug July – Aug Aug – Sept July – August Increasing Exposure Risk for Hairs  Limit use of exterior lights. • Use yellow lighting, insect- repelling bulbs. • Do not use electric insect traps as they may also kill beneficial DL insects.

E I P BTM Mitigation Strategies: Annual Cycle – Must Plan Success

Winter Feeding Feeding Larvae Pupae Imago Eggs Nests Larvae Oct – April April – June June – July July – Aug July – Aug Aug – Sept August – September Increasing Exposure Risk for Hairs  Insecticide Treatment on early instar larvae  Conduct local survey to assess scope • Citizen science reporting mechanism? DL

E I P Summary and Conclusions  Maine is facing the worst outbreak of Euproctis chrysorrhoea (BTM) in a century

 Outbreaks are likely to get worse due to a range of factors: • Climate change trends favoring BTM biology • Lack of specific primary parasites and abundance of hyperparasites • Potential for reduced in intra-specific self-limitation due to increased forest cover relative to previous outbreak

 The problem is the worst when it is the most difficult to address. • Importance of public education and proactive governance.

 Outbreak must be controlled by a regional approach • Municipal action – Maine CDC Declaration of Public Health Nuisance • Coordinated effort between municiaplities • Advocacy for state level action Questions?