Tuesday, June 15, 2021

Mosquitoes, Mosquitoes Everywhere!

The annual mosquito boom

Rainfall, especially with multiple storm systems that have saturated and flooded areas around the state, can significantly contribute to a boom in mosquito populations, Swiger said. 

“People are seeing, and should expect to see, quite a bit more mosquito activity in the next days and weeks,” she said. “Our focus is going to be disease carriers that typically become a problem in late summer and early fall. However, all this rain has created plenty of habitat for floodwater and container species.”

Swiger divides mosquitoes into those three categories – floodwater, container and stagnant – and they typically emerge in the order related to the breeding environment they prefer.

“Mosquitoes come in waves and can overlap as the season progresses,” she said. “It can help to understand what type you are dealing with, how to do your part to control them around your home and how to protect yourself and your family because we are in mosquito season.”

For more information can be found here - 

Mosquito populations booming after rains | AgriLife Today (tamu.edu)

Friday, April 2, 2021

TMCA Spring Workshop April 7th

Don't Miss this year's Texas Mosquito Control Association Spring Workshop being held virtually.

 Register by April 5th at https://texasmosquito.org. If you have questions, contact SLSWIGER@AG.TAMU.EDU

Wednesday, February 24, 2021

Winter Storm of Texas - what impact did it have on insects?

 It is only natural after having a very unprecedent storm like Uri that just shut down Texas, to start thinking of what other impacts will we see. As an entomologist, the questions I am receiving are along the lines of "how did or will the storm impact the insects this year?"

Since I grew up in Florida and did my schooling there prior to moving to Texas, I really have no first hand data on what winter does to insects. Definitely two states that don't have real winter and my home town is always above 70 to 100 degrees year-round, most years.

So I decided to ask my colleagues for their insight and basically we all say about the same thing. 

The northern counties of Texas, which do have some winter, will have little to no impact on their insect populations despite the snow and freezing temps. Reason? The insects are still hibernating. They are in their egg or pupal stage and are winterized. If the storm had hit later into spring, there could have been some impact.

In the southern counties of Texas that could have active insect stages already, there could be impact but probably only minor. It takes extended periods of freezing temperatures to affect whole populations and while a few individual insects may have been impacted, not all would have been. 

Since my main areas is mosquitoes and flies, I will address them in particular. 

For mosquitoes, I would say little impact based on the species of concern but Culex may be worth watching this year as they overwinter as adults. The others overwinter as eggs and are designed for extremes.

For flies, emergence is usually not until March to May, depending on species, and they would not be impacted by the storm. We typically do not see fly populations return until spring and while the storm has stopped any early stable fly emergence, there will be others that did not emerge yet that will in the next couple weeks and get the population back on track. 

Comments from my colleagues in regards to other insects of concern.  

“I suspect red banded stink bugs took a hit, and to a lesser degree fall armyworm.  It may delay sugarcane aphid to some extent.” From Dr. Kerns, College Station 

“The thick layer of snow and ‘subterranean’ structures, I suspect, will lead to no drastic changes in pest complex in urban or greenhouse settings this growing season – but that’s a hypothesis. Our house water line which is about 1-foot underground didn’t freeze, and even after our first snow fall, I was able to find melted snow at the soil level. Snow is quite a good insulator – so temps at the soil level (or below) didn’t reach quite as cool as ambient.” From Dr. Vafaie, Overton 

“The cold will have no effect on corn rootworm because the eggs are below ground. They can’t even freeze them out in Minnesota or Canada.” From Dr. Porter, Lubbock

 “I did get my soil thermometer out during this mess a little bit, and at the coldest we got to about 15 degrees and our soil at 6” was still at 38 degrees. We had very little snow here, and there was ice on the ground. I am interested to see how this year shakes out after that mess, and I hope the red bandeds took a hit.” Kate Crumley, Wharton, Jackson, & Matagorda Co.

 “Looked at some wheat this afternoon and did not see much of a reduction in bird cherry oat aphid numbers. The beneficial population took a big hit out of this winter weather.” Tyler Mays, Hill & McLennan Co

 “Brown marmorated stink bug overwinters as an adult in anthropogenic structures and under tree bark. It tends to survive quite well despite “polar vortexes” that occur on the East Coast. However, as noted by others, the impact will be species-dependent and whether any warm periods preceding the cold weather broke diapause too early.” Dr. Ludwick, Corpus Christi

So short answer, probably won’t be a big impact since it was still winter for most insects. If this had come after spring hatch, then things would be different. Saw bees at my house yesterday! So it is what it is. Insects are very resilient. 😊 

 Photo credits: Confessions of an Entomologist, Mosquito Joe, and Purdue Extension 

Monday, February 22, 2021

CEU classes for Vector Management

 As we  slowly enter into spring, we start to prepare for the mosquito season that will be here soon. We never know what the season will be like but one thing is for sure, we all need to keep our TDA pesticide licenses up-to-date and receive our yearly CEUs.

As a non-commercial political subdivision license holder (apply pesticides for your job), you are required to receive 5 CEU credits annually from renewal date of your license, (i.e. Feb 1 to Jan 31).  Both AG and SPCS credits will be provided, as will Animal Control, RS and Code.

Several classes are planned for Spring 2021. To register for a class near you or a virtual class, please visit 2021 CEU Vector Management Program | Livestock Veterinary Entomology (tamu.edu)

Wednesday, September 16, 2020

Nootkatone Now Registered by EPA

Formulation of Nootkatone as Repellent and Pesticide Products Against  Mosquitoes and Ticks | Federal Labs

Nootkatone, from grapefruit, gets EPA approval for use in insect repellents 

A new active ingredient, discovered and developed by the Centers for Disease Control and Prevention (CDC), has been registered by the Environmental Protection Agency (EPA) for use in insecticides and insect repellents. Products are not yet out on the market but be looking for them in coming months. 

Studies show that when products are formulated from the new ingredient, nootkatone, they may repel and kill ticks, mosquitoes, and a wide variety of other biting pests. Nootkatone is responsible for the characteristic smell and taste of grapefruit and is widely used in the fragrance industry to make perfumes and colognes. It is found in minute quantities in Alaska yellow cedar trees and grapefruit skin.

Nootkatone can now be used to develop new insect repellents and insecticides for protecting people and pets. CDC’s licensed partner, Evolva, is in advanced discussions with leading pest control companies for possible commercial partnerships. Companies interested in developing brand name consumer products will be required to submit a registration package to EPA for review, and products could be commercially available as early as 2022.

“CDC is proud to have led the research and development of nootkatone,” said Jay C. Butler, MD, Deputy Director for Infectious Diseases. “Providing new alternatives to existing bite-prevention methods paves the way to solving one of biggest challenges in preventing vector-borne diseases—preventing bites.”

Studies show that when nootkatone is formulated into insect repellents, they may protect from bites at similar rates as products with other active ingredients already available and can provide up to several hours of protection.

Having a new effective ingredient for insecticide available will assist in addressing the growing levels of insecticide-resistance to other products currently in use, according to EPA.

“EPA is pleased to be continuing our partnership with CDC on registering nootkatone, which provides another tool to help protect the American public from biting insects and ticks,” said Alexandra Dapolito Dunn, EPA Assistant Administrator for the Office of Chemical Safety and Pollution Prevention. “This new active ingredient has the potential to be used in future insect repellents and pesticides that will protect people from disease. In many areas of the United States, mosquitoes have become resistant to currently available pesticides. A new active ingredient in our toolbox will help vector-control programs.”

Mosquito- and tickborne diseases are a growing threat in every U.S. state and territory. The number of reported cases of mosquito- and tickborne diseases doubled from 2004 to 2018. Tickborne diseases represent almost 8 in 10 of all reported vector-borne disease cases in the U.S. Increasing risk from these diseases means increasing demands on federal, state, and local health departments and vector control agencies.

CDC has partnered with Evolva since 2014. In 2017, Evolva was awarded a Biomedical Advanced Research and Development Authority (BARDA) contract with the key objective of advancing the development of nootkatone and nootkatone-based products for protection against mosquito-borne diseases, including dengue and Zika. This work has been supported with federal funds from CDC and managed by the Office of the Assistant Secretary for Preparedness and Response (ASPR), BARDA, under Contract No. HHSO100201700015C.

Tuesday, August 18, 2020

With Summer Comes Blister Beetles

The presence of blister beetles is always a cause for concern but even more so as a horse owner. Blister beetles contain a chemical, cantharidin, that when consumed by horses and other livestock, can cause illness and sometimes death.

Blister beetles are known to feed on flowers and foliage of a wide variety of crops including alfalfa, ornamental plants, potatoes, soybeans, garden vegetables and other plants. Immature stages feed on grasshopper eggs, live in solitary bee hives or are predaceous, depending on species. 

Adults can be found on flowers or infested crops. Blister beetles in alfalfa fields at harvest can be killed by the harvest machinery and incorporated into the baled hay. Cantharidin is a very stable compound and remains toxic even in the dead and dried blister beetles that may contaminate alfalfa hay. Since blister beetles often occur in large groups, or swarms, within a field, dead beetles can be concentrated in a small portion of the bales.


Care should be taken to not handle them. Never handle blister beetles preserved in alcohol because the cantharadin dissolves in alcohol and will cause blisters on the skin.

Cantharidin causes irritation of the lining of the digestive and urinary system in horses. The number of beetles that result in illness is variable and depends on the sex and species of blister beetle and on the age, weight, bred and general health of the horse. The estimated number of ingested beetles that would be lethal to a horse ranges from 50-545.

For more information visit:



Friday, August 14, 2020

West Nile on the rise in DFW Area

The Texas A&M AgriLife Extension Service experts want Texans to be aware of a large rise in mosquitoes testing positive for West Nile virus in Dallas and Tarrant counties.

The state’s warm climate makes Texas a prime breeding ground for vector-borne illnesses, and recent weather conditions have only heightened the mosquito problem for many areas of the state.

“In Texas, our biggest mosquito-related concern is West Nile virus,” said Sonja Swiger, Ph.D., AgriLife Extension veterinary entomologist in Stephenville. “It has been found throughout Texas and the U.S., and even places that don’t normally have a problem like Miami have had cases in 2020. It’s just that kind of a year.”

The West Nile virus also produces symptoms in people that can be similar to some COVID-19 symptoms – fever, cough and sore throat. Anyone experiencing these symptoms should consult their doctor.

“If you think you might have contracted West Nile virus, get tested,” Swiger said. “Do not assume it is COVID-19.”

West Nile mosquito numbers on the rise

“We’re seeing numbers as high in some counties as we experienced in 2012 and that could be problematic,” explained Swiger.

“Tarrant County is currently the hotspot, so to speak, but Dallas County is also starting to see a rise in their number of infected mosquitoes and their vector index,” she said.

“Tarrant County is reporting 30% positive in some areas and 50% positive in the northeast section, which includes the cities of North Arlington, Grapevine, Watauga, Keller and North Richland Hills, to name a few.”

According to Dallas County Health and Human Services, for the week ending Aug.1, 40 mosquito traps tested positive for West Nile Virus. A total of 127 mosquito traps in Dallas County have tested positive to date for the year and there has been one human case reported.

The previous week, Tarrant County reported that 51 trapped groups, or pools, of mosquitoes tested positive for West Nile virus and that there have been 163 positive test pools for 2020 so far.

In 2012, Texas experienced its largest outbreak of West Nile virus in history with over 1,800 confirmed cases.

“Most of these victims reported they were bitten at home,” Swiger said. “So, it’s important that Texans be aware at all times and use repellents when necessary.”

When to worry

AgriLife Extension has identified 85 different species of mosquitoes in Texas, however people don’t need to worry about contracting West Nile disease from all of them – only Culex quinquefasciatus.

Swiger said without any heavy rains, the Culex quinquefasciatus population will continue to grow without chemical intervention.

“We cannot predict what the next few months will bring unfortunately, but if heavy rains are in the future, we would anticipate a decline in positives, as the mosquitoes would be washed away,” she said.

The mosquitoes that carry West Nile virus are night biters, Swiger said. People should be extra cautious when outdoors in the evenings and make sure screens have no holes and doors are kept closed at night and are properly sealed to prevent mosquitoes from entering the home.

Staying safe

“Repellents are a must and the only real way to stay safe,” said Swiger. “Use DEET, picaridin, IR3535 or oil of lemon eucalyptus, which may also be listed as paramenthane-3, 8-diol, on people over 3 years of age, to get adequate protection. These are the only ones tested with certainty to stop the disease-carrying mosquitoes.”

When you are outdoors in any area where there could be mosquitoes, it is wise to wear long sleeves and long pants. The tighter the weave of the fabric, the better protection it will offer from bites.

Mosquito basics

Male mosquitos feed only on nectar, unlike their blood-sucking counterparts. Females also feed on nectar but need blood for egg production.

There are species of mosquitoes that feed during the day and species that feed at night. That may be why it seems like there are so many mosquitoes out at dawn and dusk – during these periods, the day and night feeders may overlap.

Swiger said during the day, grassy areas with tree coverage are where mosquitoes like to be to avoid the hot sun. Mosquitoes are cold-blooded and can’t regulate their body temperature. That’s why on warmer days they seek shade and why they typically aren’t around when the thermometer dips below the mid-50s.

“People in the city may not even notice mosquitoes during the day,” she said. “But the species of mosquito that carries West Nile virus typically lives in more urban areas, so people in cities are more likely to contract West Nile virus and need to be aware.”

If you live in the country, you’ll typically encounter more mosquitoes during the day, especially when it’s wet, Swiger said.

“At night, no one is better off than anyone else when it comes to mosquitoes,” Swiger said. “Whether you live in the country, suburbs or a big city, you’ll have mosquitoes to contend with.”

Mosquitoes hibernate in the winter. Some mosquitoes spend their winter as eggs that then hatch when the weather warms up, while others hibernate as adults or larvae. Areas with a hot and humid tropical climate can experience mosquitoes year-round.

Mosquitoes and animals

Mosquitoes can transmit dangerous disease-causing parasites to dogs and horses too, including canine heartworms, Eastern equine encephalitis, EEE, Western equine encephalitis, WEE, and West Nile virus.

“We don’t see Eastern equine encephalitis much, but even one case is cause for concern, since the mortality rate for horses with EEE is 75-80%,” Swiger said. “We typically see cases in East Texas and can expect to have cases in horses again this year. But we haven’t seen a case in humans yet.”

Swiger also noted while there are currently EEE, WEE and West Nile vaccines available for horses, there are none for humans as yet.

Mosquito prevention

The first step in mosquito prevention involves finding and eliminating mosquito breeding grounds. Mosquitoes lay their eggs in or near standing water, so any stagnant water is a potential problem. Any place around the home or property where water can collect and sit for seven to 10 days is a problem to address.

Check property for standing water in clogged rain gutters, birdbaths, old tires, children’s play equipment, potted plant trays, tarps, holes in trees, bowls and buckets — literally anything that can hold standing water. Make sure to regularly change the water in any pet bowls outside.

Dump or drain stagnant water and turn over or cover items that catch and hold water. Gravel or sand can be used to fill places where stagnant water collects.

Mosquitoes, Mosquitoes Everywhere!

The annual mosquito boom Rainfall, especially with multiple storm systems that have saturated and flooded areas around the state, can signif...