South Dakota's Bats are small, and eat bugs. They feed upon
moths, beetles, and other night flying insects, consuming up to half their
body weight in insects each night.With return of the warm weather, South
Dakota is likely to see the return of the mosquito-borne West Nile Virus.
The following provides an overview of bats and mosquitoes here in SD.
All 12 identified bat species
in South Dakota are considered generalists in their selection of insect
prey, i.e., none specialize in any one particular type of insect. This
should not be grounds to dismiss their contribution to insect pest control,
including mosquitoes. The extent to which bats control any given insect
pest is dependent upon the insect's availability and population density.
Numbers of bats are greatest in areas with higher insect density. In SD,
collectives of bats are typically maternity roosts. Such roosts are formed
in close proximity to better food supplies as this prevents the adult
females from having to fly great distances while nursing a pup that is
not yet able to fly. It also is easier for juveniles to learn to hunt
and feed themselves in areas of greater insect density.
SD's bats have voracious appetites and all are exclusively insectivorous.
While larger bat species tend to prefer larger insect prey, such preferences
come into play only when there is a choice. An abundance of a particular
type of insect will result in a quick and easy meal with a minimum of
foraging (important in conserving energy if you are a lactating bat or
a juvenile trying to put on weight to get you through your first winter).
I have seen a ranch adjacent to a creek with a large maternity roost of
Myotis lucifugus (Little Brown Bat) near Buffalo, SD, whose owners swore
they had not seen any mosquitoes while surrounding ranchers complained
of it being a bad year for mosquitoes. (This is based upon interviews
conducted during a bat presentation at the ranch.) I have documented a
single bat (weighed and banded upon emergence at dusk) returning to the
roost less than two hours later with an increased body weight of just
over 45%. Such is not uncommon and can occur several times a night.
Several bat species prefer to form maternity roosts near water, as such
locations are generally associated with greater insect density and diversity.
To contend that bats do not effectively contribute to the control of mosquito
populations is unjustified. Effectiveness of such control is dependent
upon a variety of factors. In some circumstances occurring here in South
Dakota, they are very effective. There has been no research completed
in SD on the diet content of bats. Diet composition is likely to vary
between habitat types for the same species. What is true in an urban area
is likely to be different for rural areas. Anything that controls insectivorous
pests, particularly a natural control mechanism, should not be discouraged
But what about rabies? The mention of this disease as a justification
for not including them in a well-rounded control program is unwarranted.
Bats, as with nearly all mammals, can contract the disease. Bats are not
asymptomatic carriers of the virus, i.e., when they contract it, it kills
them as it does with other mammal species. Other terrestrial mammals display
higher incidence of the disease than do bats. Exposure to the virus is
far likelier to come through contact with a dog or cat than a bat. For
a bat to transmit the virus to a human, there must be physical contact
with the infected animal. The virus is not transmitted through the droppings
or the urine of an infected animal. Not handling bats reduces the chance
of contracting the disease to nearly zero. See http://www.batcon.org/”
for additional information on bats and rabies.
contributions to a healthy ecosystem far outweigh
any risks to public health with which they may be associated.
Should I put up a bat house? A lot of the information about bats and bat
houses is provided by folks trying to sell you a bat house…perhaps
not the most objective source of information (e.g., Put up one our bat
boxes and you can kiss mosquitoes good-bye!”) Bat house research
continues to refine the designs and preferred placement to optimize their
use by bats. Bat houses are most successful when properly constructed
(with proper placement) in an area where there is a shortage of roosts.
Bat Conservation Internationals web site for additional info: