|Abstract or Summary
- From May through November 1963, a mosquito survey was
made in the city of Corvallis, Oregon. The information
obtained dealt with the species of mosquitoes found,
their seasonal occurrence and the location and nature of
their larval habitats. A quantitative and qualitative
analysis of larval and adult mosquito collections by
genera and species was used to determine seasonal occurrence
Results reported here are based on a total of 309
light trap collections made in six locations, 29 aspirator
collections made in each of 11 diurnal resting sites and
larval surveys which were made every 10 days using the
During the course of the survey 6,968 specimens comprising
nine species and four genera were collected. The
species in order of abundance were Culex pipiens, Culex pens, Culex tarsalis, Culiseta incidens, Aedes increpitus,
Culiseta inornata, Anopheles punctipennis, Aedes vexans
and Aedes sierrensis. With the exception of Culiseta
inornata, a seasonal variation in abundance of all the
species favoring the late summer and early fall was observed.
Culiseta inornata was common during the spring
and early fall when temperatures were cooler.
Individual collecting techniques did not provide an
accurate, quantitative comparison of the relative abundance
of all the species. On many occasions when weather
conditions were ideal for mosquito activity, the number of
specimens that were taken in light trap collections were
not a true representative of the numbers present in the
vicinity. Culex pipiens and Culex tarsalis were taken in
large numbers in light trap collections but Aedes
sierrensis and Anopheles punctipennis were not present in
large enough numbers to indicate population trends. Conversely,
collections in diurnal resting sites included
large numbers of Culiseta incidens but very few Culiseta
inornata. The results of light trap catches however,
corresponded closely with catches in diurnal resting sites
as far as qualitative studies were concerned.
Routine larval collections from common breeding
habitats around the city were positive for all species
except Aedes vexans, Aedes increpitus and Aedes sierrensis.
These positive collections always confirmed the quantitative adult catches. The presence of the Aedes
species in the collections was probably due to adult infiltration
from breeding areas outside the city.
Larval habitats of the immature mosquitoes collected
were divided into two ecological groups. First, temporary
bodies of water which include rain pools, water troughs
and concrete structures and second, permanent bodies of
water including log ponds and sewage disposal ponds. All
these habitats gave rise to a number of generations during
the mosquito breeding season.
Mosquitoes collected from temporary habitats included
Culex pipiens and Culiseta incidens while Culex tarsalis,
Culex pens, Anopheles punctipennis and Culiseta inornata
were abundant in permanent habitats.