A two-year evaluation of elevated canopy trapping for Culex mosquitoes and West Nile virus in an operational surveillance program in the northeastern United States

The effectiveness of CO2-baited Centers for Disease Control and Prevention miniature light traps elevated in the tree canopy (approximately 7.6 m) was compared with light traps placed at ground level (approximately1.5 m) and grass-sod infused gravid traps for collecting Culex pipiens, Culex restuans, and Culex salinarius and detecting West Nile virus (WNV) activity in an operational surveillance program that encompassed 12 ecologically diverse sites in Connecticut in 2004 and 2005. More than twice as many Cx. pipiens were collected on average in light traps suspended in the tree canopy than in either light or gravid traps placed at ground level. This difference was generally restricted to those collection sites where markedly greater numbers of Cx. pipiens were collected with all trapping methods but was not associated with site-specific urbanization indices. Culex restuans was not preferentially attracted to light traps suspended in the tree canopy. No differences in the overall abundance of this species were recorded with either of the 2 trapping procedures, but both light traps were more effective than the gravid traps. Culex salinarius was significantly more attracted to ground-based light traps than traps suspended in the tree canopy, while gravid traps were ineffective at all sites regardless of the level of urbanization or any other specific land-use characteristic. CO2-baited light traps placed in the tree canopy were generally superior to ground-based light traps for detecting WNV in Cx. pipiens. West Nile virus-infected females were collected more regularly, and the frequency of infected pools was significantly greater. Twofold higher minimum field infection rates (maximum likelihood estimation [MLE] = 6.7 vs. 3.0 per 1,000 mosquitoes) were also recorded from canopy collections of this species, and virus was detected in canopy-collected females several weeks before it was detected in collections from light traps at ground level. We conclude that the use of CO2-baited light traps placed in the tree canopy for targeted trapping of Cx. pipiens and subsequent detection of WNV are likely to yield better overall results than light traps placed at ground level in this region of the northeastern United States. The virus isolation data obtained from Cx. pipiens collected in gravid traps compared favorably both temporally and spatially with results from canopy trap collections. There were no significant differences in the overall frequency of WNV-infected pools or MLEs for Cx. pipiens, but fewer total WNV isolations were made from Cx. pipiens collected in the gravid traps and virus was detected more infrequently. Results reaffirmed the utility of gravid traps as effective surveillance tools for detection of WNV in Cx. pipiens in the northeastern United States. However, findings also demonstrated that CO2-baited light traps placed in the tree canopy provided more consistent results where weekly detection of virus amplification is a critical objective. The comparative effectiveness of ground- and canopy-based light traps for detection of WNV-infected Cx. restuans and Cx. salinarius was inconclusive owing to the limited number of virus isolations that were made from these species during the 2 years of study. However, WNV virus isolations were made several weeks earlier and more frequently from Cx. restuans collected in traps placed in the canopy rather than at ground level in 2004. Results support the view that ground-based light traps are more effective for detection of WNV in Cx. salinarius.     

Light, carbon dioxide, and octenol-baited mosquito trap and host-seeking activity evaluations for mosquitoes in a malarious area of the Republic of Korea

Two field trials for commercially available and experimental mosquito traps variously baited with light, carbon dioxide, octenol, or combinations of these were evaluated in a malarious area at Paekyeon-Ri near Tongil-Chon (village) and Camp Greaves, Paju County, Kyonggi Province, Republic of Korea. The host-seeking activity for common mosquito species was determined using hourly aspirator collections from a human- and propane lantern-baited Shannon trap. The total number of mosquitoes and number of each species captured during the test were compared using 8 x 8 and 5 x 5 Latin square designs based on trap location. Significant differences were observed for the total number of mosquitoes collected in the 8 x 8 test, such that counterflow geometry (CFG) with CO2 > or = CFG with CO2 and octenol > or = Shannon trap > or = Mosquito Magnet with octenol > American Biophysics Corporation (ABC) light trap with light, CO2 (500 ml/min), and octenol > or = ABC light trap with light and dry ice > or = ABC light trap with light and CO2 > ABC light trap with light only. A concurrent 5 x 5 test found significant differences in trap catch, where Mosquito Magnet with octenol > New Jersey light trap > or = EPAR Mosquito Killer with CO2 > or = ABC light trap with light and dry ice > Centers for Disease Control (CDC) light trap (manufactured by John W. Hock) with light and octenol. Significant differences in trap catch were noted for several species including: Aedes vexans, Anopheles sinensis, An. yatsushiroensis, An. lesteri, Culex pipiens, and Cx. orientalis. Traps baited with octenol captured significantly fewer Cx. pipiens than those not baited with octenol. Likewise, no Cx. orientalis were captured in octenol-baited traps. Host-seeking activity showed a similar bimodal pattern for all species captured. Results from these field trap evaluations can significantly enhance surveillance efforts. Significantly greater numbers of mosquitoes were captured with mosquito traps using counterflow technology (e.g., Mosquito Magnet and CFG traps) when compared to standard light and carbon dioxide-baited traps. Additionally, field evaluations demonstrate that various traps can be utilized for isolation and detection of arboviruses and other pathogens.     

Selected mosquito vectors of West Nile virus: comparison of their ecological dynamics in four woodland and marsh habitats in Delaware

We compared human landing, CO2-baited light trap, CO2-baited Omni-Fay trap, and gravid trap collections of mosquitoes at 4 woodland and marsh sites with varied vegetative habitats in Delaware during summer 2001. Landing collections provided more consistent, but sometimes smaller, collection numbers than light traps. Proportions of parous mosquitoes were also higher in landing than in light trap or Omni-Fay collections about 65% of the time. Circadian feeding rhythms were observed for 3 suspected vector species selected on the basis of 1999-2000 laboratory vector competence data and their presence at local habitats. These species included Aedes vexans, Culex salinarius, and Cx. pipiens pipiens. Aedes vexans fed after dusk, primarily before 2200 h and again around dawn (0600-0700 h). Both Cx. salinarius and Cx. p. pipiens exhibited peak feeding activity after dusk and in predawn periods, as well as extended feeding periods up until midnight. Time of feeding is an important factor in evaluating vector-host associations and risks of human outbreaks.     

Effectiveness of five methods for sampling adult Culex mosquitoes in rural and urban habitats in San Bernardino County, California

The comparative effectiveness of NJ light traps, CO2-baited traps, walk-in red boxes, high-intensity light traps and gravid traps for sampling adult Culex mosquitoes for arbovirus surveillance was compared at rural dairy and residential urban habitats near Chino, California. Culex quinquefasciatus was the most abundant of the 3 species present comprising 94.9% of the 23,159 mosquitoes collected, followed by Cx. peus (4.2%) and Cx. tarsalis (0.9%). Female mosquitoes of all species were most abundant in CO2-baited traps at both urban and rural environments. Males were collected most effectively by walk-in red boxes in rural, but not urban, environments. More parous females were collected by CO2-baited traps at urban than rural habitats; however, 70-79% of all females were nulliparous and had never blood fed. These data point out the potential insensitivity of the current sampling methodology in monitoring mosquito arbovirus infection rates.     

Urbanization and the efficiency of carbon dioxide and gravid traps for sampling Culex quinquefasciatus.

The efficiency of gravid and CO2 traps for sampling female Culex quinquefasciatus was evaluated along 2 parallel 6.4 km long urban (high housing density) to rural (low housing density) transects in east Bakersfield, Kern County, CA. There were no significant differences in the number of female Cx. quinquefasciatus collected by gravid traps within urban and rural zones. The number of females collected per trap night ranged from 6.8 to 15.5. The number of females collected by CO2 traps increased significantly from 1.4 to 3.1 per trap night in urban to 31.8 to 111.2 per trap night in rural zones and was inversely correlated with housing density. These results indicate that female Cx. quinquefasciatus were effectively sampled by gravid traps in urban subdivisions and by CO2 traps in rural mixed agricultural areas.     

Comparison of several different trapping methods for Culicoides variipennis (Diptera: Ceratopogonidae)

When battery operated CDC miniature incandescent and black light traps (with and without light bulbs) were operated with and without CO2, the rank of trap effectiveness for total numbers of female Culicoides variipennis caught was: black light plus CO2; CO2-baited trap without light bulb; black light without CO2; incandescent light plus CO2 and incandescent light without CO2. In 1983, the black light trap plus CO2 caught significantly more males and females than any other traps, and the incandescent light trap without CO2 caught significantly fewer females than any other traps. There were significant differences also in times gnats were collected, as well as in the gonotrophic condition of females caught in traps and that different traps caught different physiological/reproductive segments of the population. All catches revealed that gravid females began flying only a few min before sunset and peaked in the 1st h after sunset. Because it caught significantly larger numbers of females than other traps and because it was selectively attractive to gravid and parous females, the black light trap would be the trap of choice when large numbers of parous females are desired in arbovirus isolation studies.     

West Nile virus-infected mosquitoes, Louisiana, 2002

Human cases of West Nile virus (WNV) disease appeared in St. Tammany and Tangipahoa Parishes in southeastern Louisiana in June 2002. Cases peaked during July, then rapidly declined. We conducted mosquito collections from August 3 to August 15 at residences of patients with confirmed and suspected WNV disease to estimate species composition, relative abundance, and WNV infection rates. A total of 31,215 mosquitoes representing 25 species were collected by using primarily gravid traps and CO2-baited light traps. Mosquitoes containing WNV RNA were obtained from 5 of 11 confirmed case sites and from 1 of 3 sites with non-WNV disease. WNV RNA was detected in 9 mosquito pools, including 7 Culex quinquefasciatus, 1 Cx. salinarius, and 1 Coquillettidia perturbans. Mosquito infection rates among sites ranged from 0.8/1,000 to 10.9/1,000. Results suggest that Cx. quinquefasciatus was the primary epizootic/epidemic vector, with other species possibly playing a secondary role.     

West Nile virus surveillance in mosquitoes in New York State, 2000-2004

A West Nile virus (WNV) surveillance system was created and implemented in New York State (NYS) in 2000 and described previously (White et al. 2001). We examine and evaluate the results of mosquito and virus surveillance for 2000 through 2004 exclusive of New York City. Forty-nine counties submitted 1,095,426 mosquitoes in 35,280 pools for WNV assay. Specimens of 47 species were tested, with Culex species accounting for 47.6% of all pools tested. WNV was detected in 814 pools from 10 species, with combined Culex pipiens/Culex restuans pools accounting for 90.8% of all detections. Pools submitted from gravid traps were 5.7 times more likely to be positive than submissions from carbon dioxide-baited light traps. Most human WNV cases resided in counties that conducted mosquito surveillance. Local health departments' use of mosquito surveillance information often led to an enhanced disease prevention response. In NYS, Cx. pipiens/Cx. restuans groups are most likely vectors of WNV. Future efforts to improve system efficacy are discussed.     

Evaluation of five trapping systems for the surveillance of gravid mosquitoes in Prince Georges County, Maryland

Five mosquito trapping systems were evaluated in a large wildlife research center containing extensive and diverse mosquito-breeding habitat. The systems evaluated included Centers for Disease Control (CDC) New Standard Miniature Light traps with and without CO2 (dry ice), CDC gravid traps, partially open 1.8-m3 cages, and Fay-Prince traps baited with CO2. The first 4 trap systems were evaluated for 17 periods, while the Fay-Prince trap was evaluated on 5 trapping dates. Parameters recorded for each species were total catch, percent males, total females, and whether blood-fed/gravid. Fourteen of the 23 species caught yielded over 50 individuals in the 5 trapping systems (range of 71-2,524 specimens per species). Both light and CO2 were powerful attractants for 12 of the 14 commonly caught species. However, for most species, the majority of captured females were nongravid. Gravid traps caught fewer mosquitoes than did light- or CO2-baited traps, but the catch consisted of a higher percentage of gravid females. The open cages caught substantial numbers (>100 individuals) of 5 species, and for 2 species, this was the most productive trap. While light- and CO2-baited traps tended to catch few males or gravid females, the open cages caught an eclectic mixture of males, gravid females, and nongravid females, perhaps representative of the true percentages of each in nature.     

Yeast-generated CO2 as a convenient source of carbon dioxide for adult mosquito sampling

A new, convenient method was developed to supply CO2 for mosquito sampling by using yeast, which converts sugar into CO2 and ethyl alcohol. The system could, at average, generate 32.4 ml/min of CO2 for at least 27 h. The total weight of the CO2 generated was estimated to be 94 g. The efficacy of yeast-generated CO2 as attractant for mosquitoes was significant, and the following 6 mosquito species were collected using yeast-generated CO2 traps from July to September 2003 in a residential area of southern and northern Yokohama City, Japan: Aedes albopictus (Skuse), Armigeres subalbatus (Coquillett), Culex halifaxii Theobald, Cx. pipiens pallens Coquillett, Ochlerotatus japonicus (Theobald), and Tripteroides bambusa (Yamada). Besides mosquitoes, various other insects were collected in the trap. Species compositions of insects collected in yeast-generated CO2 traps and dry-ice-baited traps were compared.     

Effects of trap design and CO2 presentation on the measurement of adult mosquito abundance using Centers for Disease Control-style miniature light traps

Centers for Disease Control miniature light traps augmented with CO2 provide an effective method of monitoring Culex abundance and may provide a useful supplement to New Jersey light traps used by the California Mosquito Surveillance Program. To assist in standardizing sampling protocols, the present research compared the catch of adult mosquitoes collected using 4 trap designs and 3 CO2 presentation methods. When augmented with dry ice, the Arbovirus Field Station (AFS) trap (consisting of a 3-in. fan mounted into a white polyvinyl chloride pipe and operated without a light source or rain shield) collected as many or more Culex females than similar traps purchased from John W. Hock and American Biophysics, or a trap with a 4.25-in. 2-bladed fan constructed by the Orange County Vector Control District (similar to the Encephalitis Virus Surveillance model distributed by Bioquip). Few blooded or gravid females and males were collected, indicating that CO2 released from the dry ice and not light probably was the primary attractant. Catch of Culex tarsalis females in traps baited with CO2 released at 0.5-1.5 liters/min from gas cylinders was significantly greater than in traps baited with dry ice, even though the CO2 release rates from the dry ice at dusk probably were comparable to that released from the cylinders and averaged 0.4-0).5 liters/min for the night. Traps baited with 0.5 liters/ min of CO2 gas released in 15 3- or 2-sec bursts per hour collected the fewest mosquitoes. In all experiments, trap location effects were significant and accounted for as much variability in catch size as trap design or CO2 presentation. Sampling efficiency of all trap designs or CO2 presentations were consistent over time, space, and different levels of mosquito abundance.     

Entomologic studies after a St. Louis encephalitis epidemic in Grand Junction, Colorado

In 1986, after a St. Louis encephalitis epidemic in Grand Junction, Colorado, in 1985, vector mosquitoes in the city were surveyed to correlate their bionomics and infection rates with the occurrence of human disease. No human cases were reported, but mosquito surveillance disclosed St. Louis encephalitis virus in Culex tarsalis and Culex pipiens pipiens. Mosquitoes were collected with gravid traps designed to attract Cx. p. pipiens and with Centers for Disease Control light traps. Culex p. pipiens was the predominant vector mosquito collected and was captured chiefly in gravid traps. The Culex tarsalis population emerged and expanded approximately one month earlier than did the Cx. p. pipiens population. Consequently, Cx. p. pipiens was the predominant vector species after August. Infection rates throughout the surveillance period (June to September) were severalfold higher in Cx. tarsalis than in Cx. p. pipiens; however, in late summer, diminished numbers of Cx. tarsalis and a persistent population of Cx. p. pipiens resulted in relatively larger numbers of infected Cx. p. pipiens. Thus, the participation of Cx. p. pipiens as a St. Louis encephalitis vector would have been underestimated in previous studies employing light traps alone. These studies provide further evidence that Cx. p. pipiens-associated urban St. Louis encephalitis and rural Cx. tarsalis-associated St. Louis encephalitis cycles may coexist in the West.     

Commercial mosquito trap and gravid trap oviposition media evaluation, Atlanta, Georgia

Field trials evaluating the effectiveness of selected gravid trap oviposition media and commercially available mosquito traps were conducted in southern Fulton County (Atlanta), GA, from June 9 to June 18 and June 24 to July 4, 2002, respectively. Total number of mosquitoes and number of each species captured during the tests were compared using a Latin square design. For the gravid trap infusion media, significant differences were found for total number of mosquitoes collected where sod > or = hay > or = hay side-by-side diluted hay > dilute hay side-by-side hay > or = oak > diluted hay. Only Aedes albopictus (oak), Culex quinquefasciatus (sod and both concentrated hay infusions), and Culex restuans (sod) were captured in significantly greater numbers using a particular infusion. Significant differences for the total number of mosquitoes collected were also observed in the commercial mosquito traps such that the gravid trap > ultra violet up-draft > or = Mosquito Magnet Pro > or = omnidirectional Fay-Prince trap with CO2 > up-draft CDC-style with CO2 > or = CDC-style with CO2. Significant differences in numbers collected among traps were noted for several species, including Aedes vexans, Aedes albopictus, Cx. quinquefasciatus, Cx. restuans, and Culex salinarius. Results from these field trap and infusion evaluations can enhance current surveillance efforts, especially for the primary vectors of West Nile virus and other arboviruses.     

Surveillance of St. Louis encephalitis virus vectors in Grand Junction, Colorado, in 1987

Grand Junction, Colorado, was the site of a St. Louis encephalitis (SLE) outbreak in 1985. Epidemiologic and ecologic investigations in 1985 and 1986 suggested that Culex tarsalis may not have been the exclusive vector in the outbreak and that Cx. pipiens may have contributed to transmission as an accessory vector. A limited field study in 1987 generally confirmed observations from 1986 that Cx. pipiens was more abundant than Cx. tarsalis in late summer when SLE virus transmission normally occurs. In both years, infection rates in Cx. tarsalis were higher than in Cx. pipiens, but in 1987 the only SLE virus isolate from Cx. pipiens was obtained early in the season. Truck trap collections showed that Cx. pipiens was the principal vector species collected, comprising 86% of the total. Light trap collections underestimated the population of Cx. pipiens; gravid trap collections gave a closer approximation of the relative proportions of Cx. pipiens and Cx. tarsalis in the vector mosquito population after midsummer.     

Field comparison of novel and gold standard traps for collecting Aedes albopictus in Northern Virginia

Aedes albopictus is a potential West Nile virus bridge vector in Northern Virginia; however, information regarding its virus transmission dynamics is limited, as this species is not readily collected in existing traps. This study used 5 replicates of a 5 x 5 Latin square to evaluate the efficiency and effectiveness of 2 novel host-seeking mosquito traps (the BG-Sentinel and the Collapsible Mosquito Trap (CMT-20) in collecting Ae. albopictus, relative to a carbon dioxide (CO2)-baited Centers for Disease Control and Prevention (CDC) miniature light trap. When used with CO2, the BG-Sentinel (with BG-Lure) collected 33 times more female Ae. albopictus per 24-h trapping period than did the CO2-baited CDC light trap. Without CO2, the BG-Sentinel (with BG-Lure) still collected over 6 times as many female Ae. albopictus as the CO2-baited CDC trap. Both configurations of the BG-Sentinel were significantly more effective than the other traps. The BG-Sentinel was also significantly more efficient in collecting Ae. albopictus and collected a high proportion of this species, both with CO2 and without CO2. The CMT-20 (with SkinLure) collected significantly more Ae. albopictus when used with CO2 than without CO2, but did not collect significantly more Ae. albopictus than the CO2-baited CDC light trap. The proportion of Ae. albopictus collected in the CMT-20 with CO2 and without CO2 did not differ significantly from the proportion of Ae. albopictus collected in the CDC trap.     

Comparison of mosquito trapping method efficacy for West Nile virus surveillance in New Mexico

As part of the West Nile virus surveillance program for the state of New Mexico, 13 sites along the Rio Grande River were sampled for mosquitoes during spring and summer 2003. We evaluated 3 different trapping procedures for their effectiveness at capturing selected species of mosquitoes. The 3 methods used were a dry ice-baited Centers for Disease Control and Prevention (CDC) light trap set 1.5 m above the ground (standard method), a CDC light trap suspended within the forest canopy, and a gravid trap set on the ground. Thirteen sites were sampled for 10 1-night periods biweekly from May through September. The relative numbers of captured Culex tarsalis, Cx. salinarius, Cx. quinquefasciatus, and Aedes vexans as well as the numbers of total recorded captures of all species were compared for each trapping method. Significant differences were observed for each species by location and by trapping method. Culex tarsalis was most commonly caught in canopy or standard CDC traps, especially in cottonwood bosque. Culex salinarius was found most frequently in association with marshy water, and was most often caught in gravid or standard light traps. Culex quinquefasciatus was captured almost exclusively in gravid traps within urban areas. Aedes vexans was primarily sampled in standard CDC light traps and found most frequently in wooded areas near floodplains. With the exception of Cx. Quinquefasciatus, no species was collected significantly more frequently in gravid or canopy traps than in the standard CDC light trap. Our findings do not support altering the methods currently used in New Mexico, namely, the use of 1.5-m CDC light traps and gravid traps. An increased use of gravid traps seems to be warranted in monitoring urban vector populations (specifically Cx. quinquefasciatus and Cx. salinarius) that may be involved in human transmission.     

Oviposition preferences of Culex restuans and Culex pipiens (Diptera: Culicidae) for selected infusions in oviposition traps and gravid traps

Field studies were conducted in southwestern Virginia to determine the ovipositional preferences of Culex restuans and Culex pipiens by using ovitraps and gravid traps baited with selected infusions. For the ovitrap collections, 4 different infusions (manure, hay, grass, and rabbit chow) were used. Significant differences among infusions were detected on most sample dates for both species. For 3 of the first 4 wk of collections, the manure infusion collected significantly more Cx. restuans than all the other infusions. The hay and grass infusions collected the majority of the egg rafts during weeks 5-9. Cx. pipiens egg rafts were absent from the first 3 wk of collections. Of the remaining 6 wk, 4 showed significant differences in attractiveness of infusions, with the hay and grass infusions preferred by Cx. pipiens. Two infusions, manure and hay, were used for the gravid trap experiment and both Cx. restuans and Cx. pipiens data were combined for analysis. Only the first 2 wk showed significance, with manure being preferred over hay in both weeks. In later collections, the relative attractiveness of the hay infusion increased. A seasonal shift in infusion preference may be related to incubation temperature during preparation of the infusions. New infusions were prepared each week and incubation was done outside. Increased attractiveness of the hay infusion coincided with higher average temperatures in July and August. Hay infusion was very effective for trapping both Cx. pipiens and Cx. restuans in southwestern Virginia and is more convenient to use than manure. However, cool outside temperatures in the early season may interfere with the fermentation process and thus incubation should be done for a longer time or brought indoors.     

Adult biting midge response to trap type,carbon dioxide,and an octenol-phenol mixture in northwestern Florida

The efficacy of Centers for Disease Control, ABC PRO, and counterflow geometry (CFG) mosquito suction traps to sample populations of adult Culicoides was investigated in northwestern Florida. These traps were baited either with a 4:1:8 mixture of octenol, 3-n-propylphenol, and 4-methylphenol alone or in combination with carbon dioxide (CO2). Control traps were operated without the octenol-phenol mixture or CO2. Four species, in order of descending abundance, were collected in all traps regardless of treatment: Culicoides mississippiensis, C. barbosai, C melleus, and C. furens. Midge abundance from traps baited with octenolphenol alone was not significantly different, regardless of species, when compared with traps without the mixture. However, when CO2 or CO2 plus the mixture was used, trap collections of C. mississippiensis and C. barbosai significantly increased, with the latter mixture exhibiting a synergistic effect on trap catch for both species. When this combination was used, the ABC PRO trap collected significantly more C. mississippiensis, whereas the CFG trap caught significantly more C. barbosai compared with all traps powered with 6-V batteries (P < 0.05). The effects of CO2 plus the octenol-phenol mixture on C. melleus collections appeared to be additive only for ABC PRO and CFG traps. Populations of C. furens were sporadic and too low (<0.5% of total collection) to determine any statistically meaningful differences. On the average, CFG traps powered with 12-V batteries only increased midge collection 1.2 times compared with similar traps powered by 6-V batteries. This increase was not significantly different (P > 0.05).     

Attractiveness of selected oviposition substrates for gravid Culex tarsalis and Culex quinquefasciatus in California

Eight potential oviposition attractants were evaluated for gravid Culex tarsalis and Cx. quinquefasciatus under insectary, outdoor cage and field conditions. With the possible exception of a steer manure infusion under insectary conditions, none of the media consistently attracted large numbers of gravid Cx. tarsalis females. Reiter medium, steer manure infusion, cattle feces and Bermuda sod were attractive to gravid Cx. quinquefasciatus. Catch size at CDC gravid traps and oviposition traps were sensitive to the number of competitive oviposition sites and trap placement.     

The Centers for Disease Control and Prevention resting trap: a novel device for collecting resting mosquitoes

Commercially available wood-fiber pots used to collect resting mosquitoes were modified to improve sampling efficiency. The modified traps, called the Centers for Disease Control and Prevention resting traps, collected 16.0 and 5.2 times more adult Culex pipiens and Cx. tarsalis than the conventional wood-fiber pots. The resting trap increases the mean number of resting mosquitoes collected per trap-night and is useful for collecting blood-engorged mosquitoes.