Pro-Pollinator: Mosquito Traps – GAT Traps

This is the third of a series of articles by Climate Action Coffee that seek to engage readers to understand the importance of native plants and pollinator insects. Today we focus using a GAT (Gravid Aedes Trap) to trap and kill egg-laying female Aedes egypti mosquitoes that can carry Zika, dengue and chikungunya viruses in Maryland.

In many ways, GATs and similar traps offer our best and safest (to humans, pets, and pollinators) mosquito management option. If you still think pesticide applications are the answer, listen to this recent Science Friday episode on NPR that discusses cutting edge biotech research to control populations of the disease-carrying mosquito Aedes aegypti, including mass sterilization, and CRISPR technology to alter their DNA. Dr. Omar Akbari from UC San Diego–the brains behind using CRISPR technology to alter the mosquito’s DNA– says that we need these techniques because Aedes aegypti are already resistant to insecticides–this is backed up by the USDA Agricultural Research Service, which says, “Pyrethroid insecticide resistance is common in Ae. aegypti in many locations worldwide.”

What is a GAT ?
GAT stands for Gravid Aedes Trap (GAT). A GAT targets Asian tiger (Aedes albopictus) and yellow fever mosquitoes (Aedes aegypti) –the mosquitoes that can transmit diseases including Zika, dengue fever and chikungunya. The GATs marketed by Biogents are often referred to as BG-GATs. But whether store bought, or homemade, they are all passive mosquito traps that use simple technology and materials to trap and kill egg-laying female mosquitoes.

What is an AGO Trap, or an Ovi Trap ?
Similar to a GAT, this trap was developed by the CDC and captures female Aedes aegypti mosquitoes in a chamber filled with water, hay and sticky paper. These are sold by AP&G under the Catchmaster brand–Ovi-Catch Mosquito Trap for about $35.00. They now even offer a model called the Ovi-Planter Mosquito Trap that disguises the trap like a planter, for people who don’t like the ugly buckets that other commercial and home-made traps use! The designer trap sells for about $80.00.

Why use a GAT/AGO?
These traps do not use pesticides to kill mosquitoes, and therefore don’t kill any non-target, beneficial insects, which is a major concern with all commercial mosquito sprays that are applied by companies like Mosquito Joe. Even the biological mosquito sprays such as garlic can harm beneficial insects. These traps don’t pose a threat to pollinators. The traps are also low cost and low maintenance. Sprays kill “all” adult mosquitoes, but not eggs, so they must be reapplied every few weeks (= more pesticides in the environment + more money) but GATs attract and trap egg-laying females.

How does a GAT/AGO kill mosquitoes ?
The GAT uses water and organic matter, which gives off carbon dioxide, to attract egg-laying female Asian tiger and yellow fever mosquitoes into a simple “trap” where the mosquitoes get caught and killed on sticky cards.

How much does a GAT/AGO cost?
The City of Takoma Park, Dept of Public Works, sells them for approximately $35.00. They are also available online from Biogents ( packs of 12 for $400). Online, a single AGO goes for $30.00 (see link above)

How do I assemble a GAT?
Above is a cross-section diagram of a BG-GAT. The diagram may look confusing, but watch this short video on how to assemble a trap and you ‘ll see that is super quick and super easy to assemble. All of the traps follow the same basic design principles.

Do I have to use/buy refills of the sticky paper in the traps?
GATs from Biogents come with plastic sticky cards, which are usually easy to slide into the trap. However, users of some traps have reported receiving kits without the correct holes or hooks to attach them. If you use them and run out, you can buy refills online. Some of the AGO traps come with large pieces of glue-covered paper that you roll into shape to fit inside of the cylinder-shaped trap. These are a lot messier than the cards! Some people skip the cards or paper, and use a spray form of cooking oil, like Pam—the idea being that the mosquitos will get coated with the oil and be unable to fly out. Experience suggests that this will kill some mosquitoes but is not as effective as the sticky cards. It is also messy, especially when cleaning traps at the end of the season.

Can I make my own GAT?
It is easy to make a DIY passive mosquito trap. All are based on the same design. All you need is a 5 gallon bucket, straw, hay, dead leaves or grass, and some Mosquito Dunks. Mosquito Dunks are donut shaped discs that contain a bacteria called Bacillus thuringiensis (Bt). You can buy them in any hardware store. This bacteria will only kill the larvae of mosquitoes and other diptera such as midges (small flies). They won’t kill the adult mosquitoes. For more detailed instructions see one of the articles/websites below:
Mosquitoes Suck. Here’s How to DIY Your Own Trap

How many GATs do I need in my yard?
Probably 3 for an average yard around here. GATs are even more effective at controlling mosquitoes in neighborhood vector control programs so please encourage your neighbors to get on board!! The more contiguous yards that use them, the more effective they will be at controlling mosquitoes. There is tons of peer reviewed research that supports this.

Where should I put the GAT?
Place the traps in places where mosquitoes shelter- humid, shady, and wind-protected locations that are protected from the rain.

Will GATs get rid of all the mosquitoes in my yard?
The traps alone aren’t enough to get rid of your entire mosquito problem. You still have to be vigilant about any standing water in your yard. Another key to controlling mosquitoes in a community is to have your neighbors use GATs too.

Natural Solutions
Alternatively, attract dragonflies which eat hundreds of mosquitoes a day! Plant monarda, rudbeckia, coneflower, butterfly weed, cardinal flower, yarrow or Joe-pye weed.
Maureen Malloy and Marguerite Cyr