Caddisflies Near CAP

Since 2004, large numbers of caddisflies have been noticed along the CAP canal and appear to be more concentrated in some urban areas. These flying insects may be an annoying nuisance but are benign in every other way. Unfortunately, there appears to be no solution to completely eliminating the fly population from the CAP aqueduct system.

Caddisfly Lifecycle

Caddisflies spend the majority of their life as larvae and attach themselves to the concrete linings of canals. At dusk and dawn, adult caddisflies emerge from the water to mate and are attracted to light. They spend the heat of the day in the shade of green foliage. The major caddisfly hatches occur in May and September and can last several weeks.

CAP's Approach

CAP has taken a proactive approach to limiting the caddisfly population by investing in research to help determine what environmental factors influence growth and life cycles. Simultaneously, CAP has been scraping the canal lining to flush the fly larvae and researching more aggressive methods that will allow for the cleaning of the canal lining several times per year.

CAP maintenance crews will be scraping the aqueduct in Phoenix and Scottsdale as follows:

Weekly (Tuesday through Friday)

April 28 through May 29
June 16 through June 26
August 4 through September 4

Areas brushed (Both sides of the canal):

From Concrete Overchute at MP 158 (Just upstream of Norterra Parkway), downstream to MP 159.7
From SR 51 downstream to 64th Street
From the Loop 101 downstream to the Salt River Pima Reservation boundary (MP 181)

What You Can Do

The following are a few techniques to help reduce the caddisfly problem near your home:

• Keep backyard lights at a low level and limit yard floodlights
• Replace white light bulbs with yellow “bug” lights
• Request that white streetlights in your neighborhood be replaced with yellow
• Reduce the amount of vegetation in your yard and surrounding your property

How To Build A Trap

Get a large bucket or tub and cut a notch in it. Fill the bucket with some water and then add about two inches of vegetable oil to the water. Mount a black light in the notch you cut in the bucket and plug it into a GFI outlet. Most homes have an exterior GFI outlet and you can tell a GFI outlet because there will be a small button above the actual plug outlet. This is for your safety. Should you drop the black light into the oil/water mixture the GFI button will pop out and cut the electrical circuit.

For more information, contact Bob Barrett at 623-869-2135 or rbarrett@cap-az.com.