Fig. 1. Percentage of complaints due to Aedes sierrensis from 1988-1999.
THE MOSQUITO
MAGNET® A NEW TOOL IN CONTROLLING TREE HOLE MOSQUITOES
Salt Lake City Mosquito
Abatement District
Salt Lake City, UT 84116
Introduction
The first tree hole mosquitoes, Ae. sierrensis, were collected in Salt
Lake City in 1987. Since that time the problems with tree hole mosquitoes have
drastically increased (Fig. 1). Tree
hole mosquitoes lay their eggs in holes, and rotted areas of trees that hold
water. Neighborhoods with older mature
trees are most affected. Although
programs are in place to control tree hole mosquito larvae, it is almost impossible
to find all sources. For example, in
densely forested areas such as along creek banks or where trees are wrapped
with leafy vines, all sources cannot be found.
For this reason there will always be adult tree hole mosquitoes. These mosquitoes are very aggressive which
makes them a neighborhood nuisance.
Fortunately, the tree hole mosquito stays fairly close to their source
area, which makes trapping them a viable control method effective. The Mosquito Magnet®, a new type of mosquito trap, was used this year by the Salt Lake City
Mosquito Abatement District. The purpose for using the Mosquito Magnet® was to find out how effective it was in temporarily reducing tree hole
mosquitoes in selected areas.
The Mosquito Magnet® is a relatively new mosquito
trap. It runs on liquid propane which
is converted, through a catalytic reaction, into carbon dioxide and warm water
vapor in similar proportions to that of human breath. The reaction also creates a small electrical charge that runs the
traps fans. The trap uses a technology
which is called a counter flow system (Fig. 2). The counter flow works by putting a smaller tube, that blows out
the attractant, inside of a larger tube that sucks the mosquitoes up into the
trap. Supposedly, mosquitoes have a
tendency to reverse direction by flying up rather than down, this behavior
brings them closer to the trap entrance.
The Mosquito Magnet® was brought to, and ran in several different locations over the course
of the summer. Three main locations
will be discussed in this paper.
1. 1166
Downington is the sight where the Mosquito Magnet® was used most. There were
large numbers of tree hole mosquitoes at this location. The back yard bordered the banks of Emigration
Creek. The back yard area, as well as
the banks of the creek had many mature trees.
To evaluate the effectiveness of the Mosquito Magnet® an ABC Pro® (American Biophysics
Company) trap was also used at this location.
The ABC Proâ trap is very similar in
design to a CDC trap. It uses a thermal
water jug filled with dry ice as its source of CO2. Below the jug is the main body of the trap,
which has some electronic components and a fan. Below the body is the net.
It uses a 7 volt motorcycle battery as a power source. The trap works by
releasing CO2 out the bottom of the jug. As the mosquitoes come close to the attractant they are sucked
down by the fan into the net. It was
set to run continuously day and night as the Mosquito Magnetâ does.
After
the Mosquito Magnet® was run for several days, it was removed and
replaced with the ABC Pro® trap for one day and night.
The ABC Pro® trap was then removed and the Mosquito Magnet®
was operated for several more days. The
two traps operated in the same location, but were never operating at the same
time.
2. 1257
Gilmer Drive is in an older up scale neighborhood. There were a number of large mature trees in the area. Some of
the trees are wrapped with leafy vines making it hard to find all of the tree
holes. The mosquitoes at this house
were numerous and the owner asked if the district could help.
3. 1709 Bryan
Avenue was another location that bordered a creek. It was also populated with many trees. The tree hole mosquitoes
were not nearly as abundant here as at the Downington location.
The Mosquito Magnet® was used more at 1166 Downington than at all other locations. This area had the biggest tree hole mosquito
problem because of the large number of trees.
Between June 11 and August 9 4,857 Ae.
sierrensis were trapped at Downington.
Over the course of the two month period, the mosquito population dropped
from an average of 401 mosquitoes per night to about 11 mosquitoes per night
(Table 1). A lot of this decrease is
probably due to natural mortality over the summer, but it is also the result of
heavy trapping in the area from the Mosquito Magnet®.
A comparison between the Mosquito Magnet® and the ABC Pro® trap was conducted at
Downington (Table 2). From July 2-6 the
Mosquito Magnet® trapped 198 Ae. sierrensis per night and zero Cx. pipiens. The ABC Pro® trap over a 24 hour day period
from July 6-7 trapped only 13 Ae.
sierrensis, but did trap 34 Cx.
pipiens. The traps were run a
second time, the Mosquito Magnet® from July 8-13 and the ABC
Pro® trap during July
15-16. The Mosquito Magnet® again trapped many more Ae.
sierrensis at 73 per night, than the ABC Pro® trap, which only trapped 7 in the 24 hour period. The ABC Pro® trap did catch 66 Cx. pipiens. The
Mosquito Magnet® appears to be better suited
for use with Ae. sierrensis than the
ABC Pro® trap.
An interesting fact about Ae. sierrensis is that the male
mosquitoes are attracted to CO2 along with the females. They do this to find females for
mating. The trap results showed this
phenomenon at all three locations (Table 3). At Downington, only 45% of Ae. sierrensis were females. But, in the ABC Pro® trap, where mostly Cx. pipiens
were trapped, 95% of all mosquitoes caught were female. At Gilmer Drive and
Bryan Avenue only 59% of mosquitoes, mainly Ae.
sierrensis, were females.
One of the main goals in using the
Mosquito Magnet® was to give residences some
relief from tree hole mosquitoes. At
1257 Gilmer Drive it seems that this goal was accomplished. This is a notorious
tree hole area. The Mosquito Magnet® was placed in the yard. Over a
three day period, from June 18-21, a total of 156 Ae. sierrensis were trapped. The trap was left another three days
and caught 50 more, a big reduction from the previous three nights (Table 4).
The Mosquito Magnet® was then taken to a new
location. Telephone calls were made to
the owner of 1257 Gilmer Drive, one and two weeks after the last trap day. With both calls the owner indicated that the
Mosquito Magnet® had really helped and that
the mosquitoes were under control.
Conclusion
The trial of the Mosquito Magnet® by the Salt Lake City Mosquito Abatement District showed that it is an
effective tool in helping control tree hole mosquitoes in Salt Lake City. It by no means got rid of all of the
mosquitoes, but it did give people some relief and peace of mind that the
mosquito abatement was trying to help.
The trap is easy to use, and once in place requires no maintenance for
up to 20 days. It is also environmentally friendly, it uses no pesticide, and
it releases no harmful substances. The Salt Lake City Mosquito Abatement
District was happy with the results of the Mosquito Magnet® in the use of trapping tree hole mosquitoes and will continue to use
it as a control method.
Fig. 1. Percentage of complaints due to Aedes sierrensis from 1988-1999.
Fig. 2. Illustration of the counterflow geometry
trap and counterflow movement of air through the trap.
Table 1. Total number of mosquitoes and number of
mosquitoes per day, caught at 1166 Downington street, off and on from June 11
to Aug. 9.
|
Dates |
Total |
#/Day |
|
June 11-14 |
1,058 |
353 |
|
June 14-18 |
1,752 |
438 |
|
June 24-29 |
858 |
172 |
|
July 2-6 |
792 |
198 |
|
July 8-9 |
150 |
150 |
|
July 9-12 |
177 |
59 |
|
July 12-13 |
36 |
36 |
|
August 6-9 |
34 |
11 |
Table 2. Comparison between the Mosquito Magnet® and the ABC Pro® Trap.
|
|
Mosquito Magnet® |
ABC Trap |
Mosquito Magnet® |
ABC Trap |
|
|||||||||
|
|
July 2-6 |
July 6-7 |
July 8-13 |
July 15-16 |
|
|||||||||
|
|
Aedes sierrensis |
Culex pipiens |
Aedes sierrensis |
Culex pipiens |
Aedes sierrensis |
Culex pipiens |
Aedes sierrensis |
Culex pipiens |
|||||
|
# Collected |
792 |
0 |
13 |
34 |
363 |
0 |
7 |
66 |
|||||
|
Avg./Night |
198 |
0 |
13 |
34 |
73 |
0 |
7 |
66 |
|||||
Table 3. Percentage of female mosquitoes trapped.
|
|
Mosquito Magnet®
|
ABC Pro® Trap |
|
1166
Downington |
45% |
95% |
|
1257 Gilmer
Drive |
59% |
|
|
1709 Bryan
Avenue |
58% |
|
Table 4. Number of mosquitoes trapped at 1257 Gilmer
Drive.
|
|
Male |
Female |
Total |
|
June 18-21 |
60 |
96 |
156 |
|
June 21-24 |
24 |
26 |
50 |
|
Total |
84 |
122 |
206 |