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Thursday, July 8, 2021

Good news, bad news about Charlestown (and area) pests

“High numbers” of Atlantic Sea Nettle Jellyfish in Ninigret and Green Hills Ponds

By Will Collette

The good news first: DEM’s regular weekly report on mosquito-borne diseases show NO sign of West Nile Virus. At least not yet. Even though Rhode Island has had no discoveries of West Nile, there was one trapped bug in Milford, Connecticut and another in Medford, Massachusetts that tested positive.

The full text of DEM’s weekly report and their advice on protecting yourself is reprinted below.

The jellyfish are a different story.

Katie Rodrigue, Principal Marine Biologist in DEM's Division of Marine Fisheries, says there are THOUSANDS of jellyfish in Ninigret Pond, seen in the western end along the East Beach side.

The sting of an eastern sea nettle is not considered to be life-threatening but can hurt like hell.

Here is the DEM and Health Department news releases in full:

RIDOH and DEM Issue Advisory About Atlantic Sea Nettle Jellyfish

The Rhode Island Department of Health (RIDOH) and the Rhode Island Department of Environmental Management (DEM) are advising the public that Atlantic Sea Nettle Jellyfish have been identified in high numbers by DEM's Division of Marine Fisheries in Ninigret and Green Hill Ponds. These ponds are in Charlestown.

Sea nettles are often present during high summer in Rhode Island. They are most common in the salt ponds in South County. People planning to recreate in ponds in this area should bring a first aid kit and add a bottle of vinegar and sting spray.

Images of Atlantic Sea Nettle Jellyfish are attached. Their stings typically cause moderate discomfort and itchy welts.

If stung:

- Remove visible tentacles with a gloved hand or a plastic bag

- Rinse the affected area in vinegar or a commercially available sting spray (or saltwater)

- Do NOT rinse with freshwater, as this can worsen the sting

- Apply heat pack or rinse under hot water

- Use an ice pack and/or hydrocortisone cream to reduce discomfort

- If symptoms worsen, seek medical attention

"There has been a high abundance of Atlantic sea nettle jellyfish in Ninigret and Green Hill Ponds lately," said Katie Rodrigue, Principal Marine Biologist in DEM's Division of Marine Fisheries.

"Their population in the ponds has been exploding over the last month or so, probably as water temperatures have increased, and last week we observed thousands of them in the western section of Ninigret Pond along the East Beach side. DEM joins RIDOH in urging the public to be vigilant while recreating in coastal ponds this summer and to carry a first-aid kit including vinegar in case of a jellyfish encounter."

While the reason for the increase in Atlantic Sea Nettle Jellyfish this summer is not yet fully understood, their numbers are expected to decline over the course over the summer. Other species of jellyfish are less of a concern, like moon jellyfish (flat disc-shape with very short tentacles), and comb jellyfish, which have no stingers at all.

Weekly Mosquito Advisory

The Rhode Island Department of Environmental Management (DEM) today announced that all 92 mosquito samples from 28 traps set statewide on June 17 and June 21 have tested negative by the Rhode Island Department of Health (RIDOH) for both West Nile Virus (WNV) and Eastern Equine Encephalitis (EEE).

To date, in Rhode Island, there have been no findings of EEE or WNV in mosquito samples. The season's first two isolations of WNV in southern New England were reported last week from one trap set in Milford, Connecticut and one in Medford, Massachusetts. 

These findings are not unexpected, as WNV has become established in North America following its introduction in 1999. The positive findings in neighboring Connecticut and Massachusetts indicate that WNV is beginning seasonal activity in our area. WNV will become more prevalent as the season progresses, so residents are advised to reduce their exposure to mosquitoes until the first hard frost.

Personal protection is the first line of defense against mosquitoes that may carry WNV, EEE, or other diseases – and the most effective way to avoid infection. With WNV and EEE established throughout the state, residents are reminded to eliminate mosquito breeding grounds and prevent being bitten, whenever possible. The following precautions are advised.

Protect yourself:

- Put screens on windows and doors. Fix screens that are loose or have holes.

- At sunrise and sundown (when mosquitoes that carry EEE are most active), consider rescheduling outdoor activities that occur during evening or early morning. If you must be outside, wear long-sleeved shirts and long pants and use bug spray.

- Use EPA-approved bug spray with one of the following active ingredients: DEET (20-30% strength); picaridin, IR3535; and oil of lemon eucalyptus or paramenthane. Always read the label and follow all directions and precautions.

- Do not use bug spray with DEET on infants under two months of age. Children should be careful not to rub their eyes after bug spray has been applied on their skin. Wash children's hands with soap and water to remove any bug spray when they return indoors.

- Put mosquito netting over playpens and baby carriages.

Get rid of mosquito breeding grounds:

- Get rid of anything around your house and yard that collects water. Just one cup of water can produce hundreds of mosquitoes; an unused tire containing water can produce thousands of mosquitoes.

- Clean your gutters and downspouts so that they can drain properly.

- Remove any water from unused swimming pools, wading pools, boats, planters, trash and recycling bins, tires, and anything else that collects water, and cover them.

- Remove or treat any shallow water that can accumulate on top of a pool cover. Larvicide treatments, such as Mosquito Dunks can be applied to kill immature mosquitoes. This environmentally-friendly product is available at many hardware and garden stores and on-line.

- Change the water in birdbaths at least once a week and rinse out birdbaths once a week.

Best practices for horse owners:

Horses are particularly susceptible to WNV and EEE. Horse owners are advised to vaccinate their animals early in the season and practice the following:

- Remove or cover areas where standing water can collect.

- Avoid putting animals outside at dawn, dusk, or during the night when mosquitoes are most active.

- Insect-proof facilities where possible and use approved repellents frequently.

- Monitor animals for symptoms of fever and/or neurological signs (such as stumbling, moodiness, loss of appetite) and report all suspicious cases to a veterinarian immediately. If you are unsure if your horse is properly vaccinated, you should consult with your veterinarian.

Visit for additional mosquito prevention tips, videos, and local data. DEM and RIDOH also remind Rhode Islanders to take precautions to avoid mosquito bites when traveling to Zika-affected countries. Pregnant women and women who are considering becoming pregnant should not travel to countries with active transmission of Zika.

Mosquitoes are trapped weekly by DEM and tested at the RIDOH State Health Laboratories. DEM issues advisories on test results from July through September, with additional reports as necessary. Test results are pending for traps set between June 23 and July 1 are pending and will be included in future announcements. Typically, positive test results trigger additional trapping to assess risk.

For more information about DEM divisions and programs, visit Follow us on Facebook at or on Twitter (@RhodeIslandDEM) for timely updates.

Related links

DEET Fact Sheet

Mosquito Dunks

Mosquito Prevention Tips