Olive fruit fly (Diptera: Tephritidae) populations in relation to region, trap type, season, and availability of fruit

Olive fruit fly, Bactrocera oleae (Gmelin), was monitored with adult captures by season and trap type, and was related to fruit volume and nonharvested fruit to elucidate the occurrence of the newly introduced pest in California. The highest numbers of adults captured in ChamP traps in olive trees, Olea europaea, were in October in an inland valley location, and in September in a coastal location. Comparisons of trap types showed that the number of olive fruit fly adults captured in Pherocon AM traps in a commercial orchard was significantly greater than in ChamP traps. A significantly greater number of females were captured in Pherocon AM traps with bait packets and pheromone lures than traps with pheromone lures alone, while a significantly greater number of adults and males were captured in traps with pheromone lures alone. Significantly more adults were captured in ChamP traps with bait packets and pheromone lures versus traps with bait packets alone. Fruit volume increased by four times from mid-June to mid-November. Olive fruit fly was found to oviposit on small olive fruit <1 cm3 shortly after fruit set, the maximum number of ovipositional sites per fruit occurred in October, and the greatest number of pupae and adults were reared from fruit collected in September and October. The highest numbers of pupae were collected from nonharvested fruit in March when high numbers of adults were captured in the same orchard.     

Distribution and dispersal behavior of Trogoderma variabile and Plodia interpunctella outside a food processing plant

The distribution and dispersal distances of insects outside of food processing and storage facilities potentially have an important influence on the population dynamics and spatial distribution of insects inside facilities. In this study, Trogoderma variabile Ballion and Plodia interpunctella (Hübner) sex pheromone-baited trap captures outside and inside a food processing facility were measured, the relationship between trap captures outside and inside the facility was evaluated, and the dispersal ability of the males of these species was assessed using self-mark-recapture stations. T. variabile and P. interpunctella males were captured in high numbers outside the food facility. The two species differed in their spatial distribution around the facility, with T. variabile being more closely associated with the proximity of the building, but most likely originating from sources outside the building. For marked T. variabile, the average recapture distance was 75 m (range 21-508 m) and for marked P. interpunctella the average recapture distance was 135.6 m (range 21-276 m). In an immigration/emigration experiment, three T. variabile marked outside were recaptured inside, but no T. variabile marked inside were recaptured outside and no marked P. interpunctella were recaptured in either location. The potential for outside populations to influence inside populations has implications for the effectiveness of different management and monitoring tools.     

Influence of trap type, trap colour, and trapping location on the capture of the pine moth, Thaumetopoea pityocampa

Studies were conducted to evaluate the effect of type, location, and colour of traps baited with 1 mg of the sex pheromone (Z)‐13‐hexadecen‐11‐ynyl acetate in polyethylene vials on the capture of the pine processionary moth, Thaumetopoea pityocampa (Denis & Schiffermüller) (Lepidoptera: Thaumetopoeidae), males. The experiments were carried out during two flight seasons in 2002 and 2003 at a low elevation Mediterranean pine forest on the hill of Goritsa (Magnesia, Thessaly, Central Greece). The hill is covered by approximately 120 ha of pines, among which Pinus brutia Ten. (Pinaceae) is predominant with Pinus halepensis Mill. (Pinaceae) as second most common species. Among the commercially available trap types used, the Delta and Pherocon II captured significantly more males than the Funnel trap. Furthermore, pine density had a significant effect on trap type and trap colour catches. Delta traps caught significantly more adults than the other two trap types in the low density pine stand, while in the medium and high‐density pine stands no significant differences were noted between Delta and Pherocon II traps. In addition, trap colour performance varied according to pine density; white‐ and yellow‐coloured traps caught significantly more males than the other two trap colours in the high‐density stand. The first adults were captured in traps during May, and traps continued to capture adults in low numbers (< two individuals per trap) until mid‐June. A period of 3–4 weeks of no trap captures followed until mid‐July, when captures restarted, at low numbers. The peak of T. pityocampa flight was observed during late August–September.     

The influence of tree species and edge effects on pheromone trap catches of oak processionary moth Thaumetopoea processionea (L.) in the U.K.

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Monitoring grape berry moth (Paralobesia viteana: Lepidoptera) in commercial vineyards using a host plant based synthetic lure

For some Lepidopteran pests, such as the grape berry moth Paralobesia viteana (Clemens), poor correlation between males captured in traps baited with sex pheromone and oviposition activities of female moths has called into question the value of pheromone-based monitoring for these species. As an alternative, we compared the capture of female and male grape berry moth in panel traps baited with synthetic host volatiles with captures of males in pheromone-baited wing traps over two growing seasons in two blocks of grapes in a commercial vineyard in central New York. Lures formulated in hexane to release either 7-component or 13-component host volatile blends captured significantly more male and female grape berry moth on panel traps compared with the numbers captured on panel traps with hexane-only lures. For both sexes over both years, the same or more moths were captured in panel traps along the forest edge compared with the vineyard edge early in the season but this pattern was reversed by mid-season. Male moths captured in pheromone-baited wing traps also displayed this temporal shift in location. There was a significant positive correlation between captured males and females on panel traps although not between females captured on panel traps and males captured in pheromone-baited traps for both years suggesting pheromone traps do not accurately reflect either female or male activity. Male moths captured in pheromone traps indicated a large peak early in each season corresponding to first flight followed by lower and variable numbers that did not clearly indicate second and third flights. Panel trap data, combining males and females, indicated three distinct flights, with some overlap between the second and third flights. Peak numbers of moths captured on panel traps matched well with predictions of a temperature-based phenology model, especially in 2008. Although effective, panel traps baited with synthetic host lures were time consuming to deploy and maintain and captured relatively few moths making them impractical, in the current design, for commercial purposes.     

Should I stay or should I go? Modelling dispersal strategies in saproxylic insects based on pheromone capture and radio telemetry: a case study on the threatened hermit beetle <Emphasis Type="Italic">Osmoderma eremita</Emphasis>

To predict how organisms cope with habitat fragmentation we must understand their dispersal biology, which can be notoriously difficult. We used a novel, multi-pronged approach to study dispersal strategies in the endangered saproxylic hermit beetle Osmoderma eremita, exploiting its pheromone system to intercept high numbers of dispersing individuals, which is not possible with other methods. Mark-release-recapture, using unbaited pitfall traps inside oak hollows and pheromone-baited funnel traps suspended from tree branches, was combined with radio telemetry (in females only) to record displacements. Dispersal, modelled as a probability distribution of net displacement, did not differ significantly between sexes (males versus females recaptured), observation methods (females recaptured versus radio-tracked), or sites of first capture (pitfall trap in tree versus pheromone trap – distance from original dispersal point unknown). A model including all observed individuals yielded a mean displacement of 82 m with 1% dispersing > 1 km. Differences in body length were small between individuals captured in pitfall versus pheromone traps, indicating that dispersal is rarely a condition-dependent response in O. eremita. Individuals captured in pheromone traps were consistently lighter, indicating that most dispersal events occur relatively late in life, which agrees with trap catch data. In addition, most (79%) females captured in pheromone traps were mated, showing that females typically mate before leaving their natal tree. Our data show that integrating odour attractants into insect conservation biology provides a means to target dispersing individuals and could greatly improve our knowledge of dispersal biology in threatened species.     

Mass trapping wild Agriotes obscurus and Agriotes lineatus males with pheromone traps in a permanent grassland population reservoir

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Contradictory results from different methods for measuring direction of insect flight

1. Stream ecologists have been puzzled by the apparent paradox that invertebrate populations persist in headwater streams despite the high frequency with which individuals drift downstream. To resolve this ‘drift paradox’, directions and distances of both larval and adult movement must be identified. Using over 50 interception traps in combination with results from several mark–capture experiments using ¹⁵N as a label, we tested the assumption that interception traps accurately represent the ultimate direction of adult insect flight. 2. In several streams in the Hubbard Brook Experimental Forest, 76% of ¹⁵N‐labelled stoneflies (Leuctra ferruginea) had flown upstream from where they emerged to where they were captured. In contrast, over 60% of stoneflies were flying downstream when captured, i.e. on the upstream side of an interception trap. 3. The instantaneous direction, as indicated by the side of the interception trap on which they were captured, indicated the ultimate flight direction for fewer than 1/3 of the individuals captured. Thus, such traps did not accurately reflect the ultimate flight patterns of individuals, as indicated by mark–capture data. 4. Conclusions drawn from interception trap counts regarding the direction of movement and the distribution and persistence of populations may need to be re‐evaluated. We suggest that better tracking methods, including mass mark–capture studies using stable isotopes, be used to evaluate the potentially complex patterns of adult insect movement and the consequences of that movement for individuals and populations.     

Impact of trap design, windbreaks, and weather on captures of European corn borer (Lepidoptera: Crambidae) in pheromone-baited traps

Pheromone-baited traps are often used in ecological studies of the European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae). However, differences in trap captures may be confounded by trap design, trap location relative to a windbreak, and changes in local weather. The objectives of this experiment were, first, to examine differences in 0. nubilalis adult (moth) captures among the Intercept wing trap, the Intercept bucket/funnel UNI trap, and the Hartstack wire-mesh, 75-cm-diameter cone trap (large metal cone trap) as well as among three cone trap designs. Second, we examined the influence of the location of the large metal cone trap relative to a windbreak on the number of moths captured. Third, we examined the relationship between nightly mean air temperature, relative humidity, wind speed, precipitation, and the number of moths captured in large metal cone traps. The number of moths captured was significantly influenced by trap design, with large metal cone traps capturing the most moths. Wing and bucket traps were ineffective. Differences among trap captures were significant among trap locations relative to a windbreak. Under strong (>14 kph) or moderate (7 <14 kph) wind speeds, traps located leeward of the windbreak captured the most moths, but when wind speeds were light (<7 kph), traps not associated with windbreaks captured the most moths. The multiple regression model fitted to the relationship between number of moths captured per Julian date and nightly weather patterns was significant. Nightly mean air temperature was the most influential parameter in the model, and its relationship with moth capture was positive.     

Attraction of Bactrocera dorsalis (Diptera: Tephritidae) and nontarget insects to methyl eugenol bucket traps with different preservative fluids on Oahu Island, Hawaiian Islands

Attraction of oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), and nontarget insects to preservative fluids ethylene glycol antifreeze, propylene glycol antifreeze, or mineral oil in bucket traps that contained captured decaying male oriental fruit flies, a male lure (methyl eugenol), and a toxicant (DDVP vapor insecticidal strip) were compared with dry control traps. Significantly (P < 0.05) greater numbers of B. dorsalis were captured in propylene glycol antifreeze traps than in other attractant trap types. Among attractant trap types with lowest negative impacts on nontarget insects, control traps captured significantly lower numbers of three species and one morphospecies of scavenger flies, one species of plant-feeding fly, and one species each of sweet-and lipid-feeding ants. Mineral oil traps captured significantly lower numbers of two species of scavengers flies and one morphospecies of plant-feeding fly, and one species of sweet-feeding ant. Because of the fragile nature of endemic Hawaiian insect fauna, the propylene glycol antifreeze bucket trap is best suited for use in environments (e.g., non-native habitats) where endemic species are known to be absent and mineral oil traps are more suited for minimizing insect captures in environmentally sensitive habitats.     

Effect of trap type, trap color, trapping location, and pheromone dispenser on captures of male Palpita unionalis (Lepidoptera: Pyralidae)

Field studies were conducted to evaluate the influence of trap design, trapping location, type of pheromone dispenser, and trap color on the capture of Palpita unionalis (Hübner) males, in olive groves. The experiments were carried out in two regions, Alexandria (northern Greece) and Oropos (central Greece), where olives are cultivated. In both regions, the majority of the males (> 70% of the total) were caught from late autumn to early winter, whereas < 1% was caught during July and August. Among the trap types used, the Funnel was significantly more attractive than Delta, Pherocon 1C, and Pherocon II traps. More males were caught in traps placed at the periphery of the groves than those placed in the center. Among the four colored traps tested, white traps were the most effective. However, a significant difference in trap catches was found between white and brown traps. Traps baited with red rubber septa captured more males than those baited with the white one. The use of these parameters in monitoring and managing P. unionalis is discussed.     

Stored-product insects associated with a retail pet store chain in Kansas

The types and numbers of insect species associated with eight Kansas retail stores belonging to a pet store chain were surveyed during February to August 2001. Insects were monitored at 1-3-wk intervals using food- and pheromone-baited pitfall traps for beetles and pheromone-baited sticky traps for moths. Thirty traps of each type were placed within a store. Thirty insect species belonging to 20 families in four orders were recorded from the eight stores. The weevils, Sitophilus spp.; Indianmeal moth, Plodia interpunctella (Hübner); and merchant grain beetle, Oryzaephilus mercator (Fauvel), were the most common and abundant species in all stores, whereas the red-legged ham beetle, Necrobia rufipes (Degeer), and red flour beetle, Tribolium castaneum (Herbst), were abundant only in one store. The numbers of each insect species captured varied from store to store. In each of the stores, a total of 12-19 stored-product species were captured in traps, and seven of the eight stores had relatively high species diversity. With the exception of one store, the different types of insect species found among the remaining seven stores were essentially similar. The mean density of insects in infested bulk-stored and bagged pet food products removed from a store ranged from 65 to 656 adults/kg. The types and numbers of insect species captured in traps indicated that infestations were well established in the surveyed stores. Early detection and management of these infestations is critical for maintaining quality and integrity of food products sold in the pet stores.     

Modelling female mating success during mass trapping and natural competitive attraction of searching males or females

Simulation models of insects encountering sex pheromone with or without mass trapping in which the searching sex is either male (moths and many insect species) or female (some true bugs, beetles, and flies) were developed. The searching sex moved as a correlated random walk, while the opposite sex remained stationary (calling) and released an attractive sex pheromone. The searching sex was caught when encountering a pheromone‐baited trap, and females mated when encountering a male. An encounter with pheromone was defined by the searcher's interception of a circle termed the effective attraction radius (EAR_c). Parameters of movement (speed and duration), initial numbers of calling sex and searching sex, number of traps, area, and EAR_c of traps and calling sex were varied individually to evaluate effects on the percentage of females mating. In the natural condition without traps, female mating success in both models was identical. Increasing the EAR_c of the calling sex caused diminishing increases in female mating success, suggesting that evolution of larger pheromone release and EAR_c is limited by increasing costs (production/sensitivity) relative to diminishing increases and benefits of mating encounters. With mass trapping, increasing the EAR_c of traps or density of traps caused similar declines in female mating in both models, but the female‐searching model predicted slightly lower mating success than the male‐searching model. Increasing the EAR_c of calling insects or the initial density of insects caused similar increases in female mating in both models, but again the female‐searching model had slightly lower mating success than the male‐searching model. The models have implications for mating lek formation and for understanding the variables affecting the success of mass trapping programs for insect pests with either male or female sex pheromones.     

Insect-attracting and antimicrobial properties of antifreeze for monitoring insect pests and natural enemies in stored corn

Insect infestations in stored grain cause extensive damage worldwide. Storage insect pests, including the Indianmeal moth, Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae); Sitophilus spp. (Coleoptera: Curculionidae); and their natural enemies [e.g., Cephalonomia tarsalis (Ashmead) (Hymenoptera: Bethylidae), and Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae)] inhabit a temporary, but stable ecosystem with constant environmental conditions. The objective of the present experiment was to assess the efficacy of using ethylene glycol antifreeze in combination with nutrient solutions to monitor storage insect pest and natural enemy populations in three bins of corn, Zea mays L. The treatments were deionized water, a diluted (1:5 antifreeze:water) antifreeze solution, 10% honey, 10% honey in the diluted antifreeze solution, 10% beer in the diluted antifreeze solution, 10% sucrose in the diluted antifreeze solution, and a commercial pheromone trap suspended in a 3.8-liter container filled with 300-ml of diluted antifreeze solution. The seven treatments captured storage insect pests and their natural enemies in the bins at 33-36 degrees C and 51-55% RH. The pheromone trap in the container with the diluted antifreeze captured significantly more P. interpunctella than the other treatments, but a lower percentage (7.6%) of these captures were females compared with the rest of the treatments (> 40% females). All trapping solutions also captured Sitophilus spp. and other beetle species, but the captures of the coleopteran pests were not significantly different among the seven treatments (P > 0.05). Two parasitoid wasps also were captured in the study. The number of A. calandrae was different among the seven treatments (P < 0.05), whereas the number of C. tarsalis was not different among the treatments (P > 0.05). Most A. calandrae adults were captured by the 10% honey in the diluted antifreeze, whereas the fewest were captured in the deionized water. Microbial growth was observed in the 10% honey solution, but no microbial growth occurred in the rest of the treatments, including 10% honey in the diluted antifreeze solution. The results of insect captures and microbial growth demonstrated that antifreeze could be used as a part of storage insect monitoring and/or control programs.     

Efficiency of volatile baited sticky traps for the Tarnished Plant Bug (Lygus lineolaris) in strawberry fields

Insecticides have adverse effects on human health and the environment. Thus, the development of non-chemical replacement to manage insect pests is urgent. An alternative is to bait sticky traps with attractive insect sex pheromones or plant volatiles. In Quebec, the tarnished plant bug (Lygus lineolaris) is a major insect pest. We tested the efficiency of sex pheromones (mixture of hexyl butyrate (HB), (E)-2-hexenyl butyrate (E2HB) and (E)-4-oxo-2-hexenal (KA)) and sunflower (Helianthus annuus) volatiles (pinene, sabinene and phenylacetaldehyde) as sticky trap baits for the tarnished plant bug in strawberry fields of the Laurentians in Southern Québec, Canada. The pheromones decreased the number of tarnished plant bug caught in the traps compared to a control. The sunflower volatile did not have any effect on the number of individuals caught in the traps. Different Lygus species use HB, E2HB and KA in different ratios for sexual signals and alarm signals and for species recognition. GC-MS analysis of the sex pheromone bait revealed that the ratios between the three main compounds did not match the intended ratio for the L. lineolaris species. This mismatch probably explains our results. Individuals were not attracted to sunflower volatiles. Our results point to the difficulty of manufacturing and using sex pheromones as baits. Future work should assess the effect of several pheromone ratios.     

How varying pest and trap densities affect Tribolium castaneum capture in pheromone traps

The red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), is an important insect pest in food processing facilities. Pheromone trapping is frequently used to monitor red flour beetle populations in structures; however, the optimal trap density and the relationship between trap captures and beetle density is not known. Two experiments were performed concurrently in environmentally controlled 30‐m² walk‐in chambers to determine the relationship between aggregation pheromone trap captures of red flour beetles and beetle and trap number. In one experiment, beetle density was kept constant at 200 individuals per chamber while trap number was varied from 1 to 8, and in the other experiment trap number remained constant at one per chamber while beetle density varied from 20 to 800 individuals. Results indicated that approximately one out of 23 red flour beetles were captured in a trap. Number of beetles captured in traps increased significantly as beetle density increased; however, the proportion of beetles captured remained consistent across beetle densities with a mean of 4.7 ± 0.6% of individuals captured. Trap captures varied significantly with trap placement within experimental chambers, indicating that subtle differences in the trapping environment can influence trap captures. Data suggested that trap densities of 0.07–0.10 m^?2 (2–3 traps per chamber) would maximize trap capture, whereas a trap density of 0.13 m^?2 (four traps per chamber) would maximize the predictive ability of a trapping equation estimating beetle density from trap captures. Results provide information needed to more thoroughly explore how environmental factors might influence red flour beetle trap capture in the absence of changes in beetle density. Further understanding of these relationships will allow for more accurate assessments of absolute beetle density from pheromone trap capture data.     

Movement patterns of selected insect groups between natural forest,open land and rubber plantation in a tropical landscape (southern Yunnan,SW China)

In many regions of tropical Asia, the expansion of rubber monoculture plantations is conducted by replacement of natural forest areas and strongly affects biodiversity and movement patterns of wild species, including insects. Against this background, we conducted a study on selected insect groups (longhorn beetles, bark beetles, wild bees and hoverflies) along transects between rainforest patches, open uncultivated land and rubber plantation habitats in a region of Xishuangbanna (southern Yunnan, China), with the objectives to identify (a) movement directions and patterns of selected insect groups based on their abundances in modified Malaise traps in the different habitats, and (b) the role of remaining natural rainforest patches and rubber plantations, respectively, for insect diversity maintenance and conservation. The highest total numbers of species and individuals of bark beetles, longhorn beetles and wild bees were recorded from the natural forest edge compared to open land and rubber plantation edge. This result clearly indicates that the natural forest plays an important role in maintenance of these three insect groups. However, the highest number of hoverfly species and individuals was recorded from the open land sites, indicating the most relevant habitat type for this group of species. Overall, the lowest species and individual numbers were recorded from the rubber plantation edge, indicating the unsuitability of this habitat type for all insect groups considered. The distribution of species and individuals in the opposite trap sides along the transect indicates that longhorn beetles, bark beetles and wild bees show not only movements from the forest to the surrounding habitats, but also return back after encountering the unsuitable rubber plantation habitat. Bark beetle composition showed the relatively highest similarity between all trap sites and opposite trap sides among the insect groups considered, indicating a higher movement activity than the other groups. The four insect groups considered in this study show different movement modes between the forest, open land and rubber plantation, which are not the same for all taxa. Except for hoverflies, the natural forest was found to be the most important habitat for the maintenance of species diversity in the different land use types of the study area.     

Stored-product insects associated with eight feed mills in the midwestern United States

Commercial food- and pheromone-baited pitfall traps and pheromone-baited sticky traps were used during 2003 to survey stored-product insect adults in eight participating feed mills in the midwestern United States. Across the eight feed mills, 27 species of beetles (Coleoptera) and three species of moths (Lepidoptera) were captured in commercial traps. The red flour beetle, Tribolium castaneum (Herbst), was the most abundant insect species captured inside the eight mills. The warehouse beetle, Trogoderma variabile (Ballion), was the most abundant insect species outside the mill and in the mill load-out area. The Indianmeal moth, Plodia interpunctella (Hübner), was the most abundant moth species inside the mill and in the mill receiving area. The Simpson's index of species diversity among mills ranged from 0.39 (low diversity) to 0.81 (high diversity). The types of species found among mills were different, as indicated by a Morisita's index of <0.7, for the majority of mills. The differences in the types and numbers of insect species captured inside, outside, in receiving, and in load-out areas could be related to differences in the types of animal feeds produced and the degree of sanitation and pest management practiced.     

Physical Factors Influencing Orientation of <Emphasis Type="Italic">Tyrophagus putrescentiae</Emphasis> (Schrank) (Sarcoptiformes: Acaridae) to Food-Baited Traps

Tyrophagus putrescentiae (Schrank) (Sarcoptiformes: Acaridae) is a serious pest of post-harvest durable stored food products for which traps are being developed as important tools for integrated pest management. This work addresses the effects of trap design, trap location, time of response, and light on the orientation of released groups of 7200 pedestrian T. putrescentiae to food-baited traps in experimental rooms maintained in full darkness at 28 °C and 70% RH. A standard trap made from a disposable Petri dish and four commercially produced stored-product pest traps of different designs were compared and evaluated for efficacy in trapping mites. Subsequent experiments evaluated the effect of trap placement, trapping duration, and light on mite capture. More mites were captured in the standard Petri dish trap when compared singly or side by side with four different commercial trap designs, so the standard trap was used in all other studies. Further experiments found that mites could be trapped 1 h after release at a distance of 2 m from the release point and at six meters from a mite source within 24 h. A greater number of mites were caught in traps placed along a wall than those away from a wall, demonstrating thigmotaxis to an edge. Traps at various heights on a shelf rack suggested that walking mites tended to be positively geotactic whether the source of mites was from the floor or from the top shelf at 1.8 m from the floor. More mites were caught in black-painted traps than in unpainted clear plastic traps in fully lighted rooms, suggesting that mites seek refuge from brightly lighted conditions. Light emitting diodes deployed with traps or assayed alone determined mites oriented positively to traps with violet or ultraviolet, with least preference to green, yellow, red and white lights. This research provides new information on orientation by T. putrescentiae that may help optimize trap designs and trap deployment for pest management decisions.     

Optimal pheromone trap density for mass trapping cacao mirids

Sahlbergella singularis Haglund and Distantiella theobroma (Distant) (Heteroptera: Miridae) are the key insect pests of cacao in Ghana and elsewhere in West Africa. Since 1954, spraying with synthetic insecticides has been the principal means of controlling these pests. In West Africa, environmental concerns, economic stimuli, and unreliable access to insecticides have stimulated interest in ecologically more benign mirid control strategies as an alternative to a total reliance on insecticides. Males of both mirid species, and those of the less damaging Bryocoropsis laticollis Schumacher, respond to the same synthetic sex pheromone blend, so pheromone‐based strategies may provide control as well as monitoring opportunities. Pheromone traps were deployed for 3 months at nine densities between two and 30 traps per 0.1 ha plot (20–300 traps ha^?1) plus an untreated control treatment in a replicated large‐scale field experiment on mature mixed Upper Amazon hybrid cacao in Ghana, in order to determine the optimal dispenser density for mass trapping, lure‐and‐kill, and/or lure‐and‐infect. At the end of the trapping period, mirid populations in the various treatments were assessed by insecticide knockdown on 400 trees and by searches to hand height on 1 200 trees, together with an assessment of mirid damage. In total 781 S. singularis and 235 D. theobroma were captured in the pheromone traps. The optimal dispenser density for S. singularis was 150 traps ha^?1. Over 300 traps ha^?1 was probably optimal for D. theobroma as a smaller proportion of the population was captured, and numbers caught per trap displayed no decline with increasing trap density. From insecticide knockdowns, mirid population density was estimated at 220–230 ha^?1, 63% of which were D. theobroma. Too few pods and orthotropic shoots were damaged by mirids to establish the efficacy of pheromone trapping for mirid control.