NZ542745A - Carbon dioxide insect trap with anti-dispersal top shield - Google Patents

Abstract

An insect trapping device includes a source of carbon dioxide such as a fuel burner (detail B) and an exhaust 28 through which the carbon dioxide is vented in an upward direction. A suction device 36 draws air and entrained insects into the apparatus, the insects being drawn through the region near where the carbon dioxide is exhausted. The insects drawn into the apparatus are retained and a top shield 38 is provided concentric with and above the exhaust to reduce dissipation of the exhausted carbon dioxide into the surrounding air.

Description

^ 3.7^-5 1 "Insect Trapping Device" 2 3 The present invention relates to a device for 4 attracting and/or trapping insects. More specifically, the invention provides a device for 6 attracting, capturing and killing haematophagous 7 flying insects. 8 9 Background to the Invention Bloodsucking (haematophagous) flying insects are 11 commonly attracted to a potential living blood 12 source such as a human through the detection of a 13 mixture of carbon dioxide, air and water vapour 14 present in exhaled breath. Thus the insects are attracted towards a specific concentration of gases 16 released at a specific temperature. 17 18 Insects are also known to be attracted to traps by 19 the use of lights or attractants such as sugar-based solutions or chemical attractants. Once in the 21 • vicinity of the trap various means are commonly used 22 to contain or kill the insects. Such means include CONFIRMATION COPY 2 1 drowning or use of insecticides. Further insect 2 traps, such as those typically designed for the 3 trapping of mosquitoes, are also known in the field. 4 In these traps carbon dioxide gas and/or chemical attractants such as octenol are released into the 6 vicinity of the trap. This carbon dioxide and 7 attractant mixture attracts insects along 8 aconcentration gradient towards the trap. Once in 9 the vicinity of the trap a suction mechanism is used to draw the mosquitoes into the trap, where they are 11 retained until they die or are disposed of. 12 13 International PCT Patent Publication No W099/37145 14 describes one such device. Hydrocarbon gas fuel is burnt to produce a gaseous mixture of carbon dioxide 16 and water vapour. The gases are then released 17 downwardly. Insects attracted towards the device 18 are drawn into the device by suction and are thus 19 trapped. 21 However, the release of the carbon dioxide and 22 attractant from such prior art traps causes their 23 rapid dissipation into the surrounding atmosphere, 24 particularly in exposed or windy conditions. The dissipation of the attractants into the atmosphere 26 results in their becoming too diluted to provide an 27 effective concentration gradient which can attract 28 the mosquitoes towards the trap. As such, they 29 become ineffective for insect attraction. 31 A further disadvantage to the presence of peripheral 32 air currents is the dissipation of heat from the 3 carbon dioxide and attractant mixture. Mosquitoes are commonly attracted to heated gaseous mixtures and thus where the gas emitted is not maintained at optimal temperature, the efficiency of insect capture is much reduced.

The generation of carbon dioxide and attractant such that it is expelled about the periphery of a trap is an important step in the function of insect traps. However, the dissipation of the attractant-containing gases results in the traps losing trapping efficiency and also being less energy efficient as more carbon dioxide needs to be produced to provide an emission level which can be detected by insects.

Summary of the Invention* ;According to a first aspect of the present invention, there is provided an insect trapping apparatus including: ;a source of carbon dioxide; ;an exhaust means from which the carbon dioxide is exhausted in an upward direction; ;a suction means for drawing air into the apparatus and being adequate to allow the ingress of insects contained within the air, the insects being drawn into the apparatus at an area proximal to where the gas is exhausted from the apparatus; ;means for retaining the insects which are drawn into the apparatus; and at least one anti-dispersal means for reducing dissipation of gas exhausted from the apparatus, ;wherein the anti-dispersal means is in concentric arrangement above the exhaust means. ;* The objects/advantages stated in the "Summary of the Invention" are those of at least preferred embodiments of the invention. It is n necessary for every embodiment to satisfy all stated advantages of the invention. jiiNTELLECTUAL PROPERTY OFROF OP N.Z. 2 0 MAR 2007 RECEIVED 4 1 Preferably the exhaust means is adapted to direct 2 the exhausted carbon dioxide substantially towards 3 the anti-dispersal means. 4 Preferably the exhaust means includes an exit port 6 through which the carbon dioxide is exhausted. 7 8 Anti-Dispersal Means 9 Preferably the anti-dispersal means is positioned in spaced arrangement with the exit port. More 11 preferably the anti-dispersal means is located above 12 the exit port. More preferably still the anti- 13 dispersal means is concentric with the exit port. 14 For example, in a preferred embodiment the centre of the anti-dispersal means may be located several 16 centimetres above the centre of the exit port such 17 that the anti-dispersal means provides equal cover 18 on all sides of the exit port. 19 2 0 The anti-dispersal means can be composed of at least 21 one carbon dioxide retaining plate member extending 22 around the exit port and thus defining a carbon 23 dioxide retaining area. The carbon dioxide 24 retaining area is preferably located around the exhaust means, more preferably around the exit port. 26 27 The anti-dispersal means serves to shelter the plume 28 of exhausted gases from peripheral air currents and 29 their cooling effect, thus preventing the dissipation of the attractant gases into the 31 atmosphere. The exhausted attractant mixture is 32 therefore concentrated around the device, generally 1 in the region of the carbon dioxide retaining area. 2 The concentration gradient that the insect follows 3 is thus increased and insects are more effectively 4 attracted to the device where they can be trapped. 6 The at least one carbon dioxide retaining plate 7 member may be any shape suitable to define the 8 carbon dioxide retaining area. The member may 9 typically be planar, arcuate or a combination of both. 11 12 In a preferred embodiment, the anti-dispersal means 13 is of a generally inverted dish shape i.e. is 14 concave towards the exit port. Thus the carbon dioxide retaining plate member may curve downwardly 16 towards the exit port at its peripheral edge(s). 17 18 Preferably the at least one carbon dioxide retaining 19 member is a series of flanges projecting outwardly 2 0 from the apparatus. Each flange preferably extends 21 outwardly from a side of a central planar hexagonal 22 plate at an angle such that a carbon dioxide 23 retaining area is defined around the exit port 24 through which the gases are exhausted. 26 The hexagonal plate may be positioned in any 27 position suitable for retaining carbon dioxide in 28 the vicinity of the exit port. For example, the 29 hexagonal plate may preferably be positioned above the exit port. 31 6 1 A further advantage of the anti-dispersal means is 2 that it prevents the escape of attracted insects 3 such that they are more easily trapped. 4 The anti-dispersal means also serves as a weather 6 cover. Precipitation is thus prevented from 7 entering the system and the carbon dioxide exhausted 8 is kept within the local vicinity of the device. 9 Carbon Dioxide Source 11 The carbon dioxide source may be any suitable source 12 of carbon dioxide. For example, the carbon dioxide 13 source may be a pressurised canister of carbon 14 dioxide. Alternatively, the carbon dioxide can evaporate from a source of dry ice. Preferably the 16 carbon dioxide is produced by the combustion of a 17 mixture of gas and air, most preferably in the 18 presence of a catalyst. 19 Preferably the gas is a hydrocarbon gas such as 21 propane, butane or a suitable mixture thereof. 22 Alternatively, the gas is Patio Gas™, a 23 propane/butane mixture supplied by Calor UK. 24 The gas is preferably stored within a container and 26 discharged via a 37mb pressure regulator. The gas 27 container is preferably stored within the device in 28 a self-contained housing. The gas preferably enters 29 the combustion chamber through a nozzle which controls gas flow and pressure. 31 7 1 The skilled reader will be aware that the regulated 2 pressure of gas supplied from containers may vary in 3 different countries and therefore modifications to 4 the nozzle may be required to obtain effective functioning of the apparatus. Such modifications 6 will be obvious to the skilled man. For example, 7 with a regulated pressure of 37mb, a nozzle size of 8 0.3mm is suitable to allow sufficient gas to feed 9 into the combustion chamber for a power requirement of 0.25kW. 11 12 Typically, the nozzle housing has at least one hole 13 to permit the flow of gas to draw the required 14 amount of air into the system to allow complete combustion. Complete combustion means that no 16 hydrocarbons are included in the gas which is 17 exhausted from the apparatus. 18 19 Preferably the carbon dioxide is mixed with air 2 0 prior to being exhausted from the apparatus. The 21 apparatus preferably further includes a second 22 suction means for drawing air into the apparatus. 23 24 The air to be mixed with the carbon dioxide is typically drawn into the device via the second 26 suction means. Typically when the carbon dioxide is 27 produced from the combustion of a mixture of gas and 28 air, the carbon dioxide is exhausted as a mixture of 29 carbon dioxide, air and water vapour. Combustion typically takes place within a combustion chamber, 31 which is preferably manufactured from cast 32 aluminium. 8 1 2 Preferably the second suction means, for the suction 3 of air, is provided by a venturi arrangement. For 4 the purposes of the present invention a venturi arrangement is defined as an opening which narrows, 6 causing a build-up of pressure sufficient to draw 7 air into the apparatus of the invention. 8 9 Catalyst The catalyst is preferably one which allows the 11 combustion of gas and air without a flame and which, 12 when operating at full working temperature, results 13 in the release of carbon dioxide. The catalyst is 14 preferably in the form of a monolith block. 16 Preferably the catalyst is a substrate coated with 17 at least 2 00m2/g platinum. The greater the surface 18 area of the catalyst, the better the performance of 19 the catalyst at comparable precious metal content. 21 Pelleted catalysts have a lower surface area (< 22 100m2/g) than coated substrates (>200m2/g) as the 23 pellets are packed together reducing the available 24 surface area. Coated substrates such as that of the present invention have a greater resistance to 26 higher temperatures and against contaminants. They 27 also contain oxygen storage compounds making the 28 combustion process easier to initiate than beaded 29 catalysts. For example, ignition within the present apparatus typically requires only one spark. 31 9 1 The catalyst has the advantage that it has better 2 resistance against high temperatures. The catalyst 3 typically burns in the region of 500°C to 1500°C. 4 The ability to withstand high combustion temperatures means that contaminants such as carbon 6 monoxide are not produced so that carbon deposits 7 from the hydrocarbon gas source do not build up on 8 and detrimentally affect the functioning of the 9 catalyst. 11 A wide range of catalysts are known in the art and a 12 suitable catalyst will be known to the skilled man. 13 14 The catalyst is typically housed in a chamber. 16 Carbon Dioxide Exhaust 17 Preferably the carbon dioxide concentration 18 immediately following combustion is between 6000 to 19 12000 ppm at a temperature which is preferably in the region of between 160°C to 210°C. More 21 preferably the carbon dioxide is exhausted at a 22 concentration of between 8000 to 10000 ppm carbon 23 dioxide at a temperature of 190°C. 24 In one embodiment of the present invention, the 26 carbon dioxide mixture is exhausted from the 27 apparatus at a concentration of between 500 to 10000 28 ppm, more preferably between 600 to 7000. Most 29 preferably the carbon dioxide mixture is exhausted at a concentration of approximately 4600 ppm. 31 1 The temperature of the carbon dioxide mixture on 2 exhaustion from the apparatus may be at a 3 temperature of between 22 and 45 °C, preferably 4 between 24 and 42°C. Most preferably the temperature of the carbon dioxide mixture is 6 maintained at between 10 to 15 °C above ambient 7 temperature (i.e. above the temperature of the 8 surrounding atmosphere). 9 Preferably the carbon dioxide mixture is exhausted 11 from an exhaust pipe, or similar outlet means, 12 through the exit port. 13 14 Preferably the outward flow of the exhausted carbon dioxide is effected by at least one fan. The fan 16 may suitably be a 40mm fan. 17 18 The exterior end of the exhaust pipe may be oriented 19 in any direction suitable for the attraction of insects. Preferably the exterior end of the exhaust 21 pipe is oriented in an upwards direction. The 22 gaseous attractant mixture is therefore preferably 23 exhausted upwardly. 24 An output of approximately 4600 parts per million 26 (ppm) carbon dioxide at a temperature 10 - 20 °C 27 above ambient temperature is preferred. An output 28 velocity of between 3 to 3.5 km/h or 1.5 to 2 mph is 29 also preferred. This level of output ensures that the denser carbon dioxide does not sink immediately 31 upon exhaustion. 32 11 1 Preferably an insect attractant is added to the 2 carbon dioxide prior to it being exhausted. 3 Alternatively, a cartridge containing the insect 4 attractant is located near to the exterior exit port of the exhaust means. 6 7 Preferably the attractant is an insect sex 8 attractant pheromone. More preferably the 9 attractant is octenol (l-octen-3-ol).

Alternatively, the attractant is octanol, octonal, 11 1-heptanol, 3-octanol or the like. 12 13 Insect Trapping 14 Preferably the first suction means is provided by at least one fan, more preferably two fans. The at 16 least one fan may suitably be a 92mm fan. A suction 17 rate of 4.5 to 5.5 km/h or 2 to 3.5 mph is 18 preferred. 19 The at least one fan is preferably driven by 21 thermoelectric generation. Preferably at least two 22 thermoelectric generators are connected in series 23 and are further connected in series to the at least 24 one fan, forming an electrical circuit. More preferably four thermoelectric generators are used. 26 27 Thermoelectric generators suitable for use with the 28 invention will be known to the skilled man. 29 Suitable thermoelectric generators can be obtained from suppliers such as Melcor, FerroTec and 31 Supercool AB. Such thermoelectric generators can be 32 manufactured to the specification required for use 12 1 with the apparatus. A single thermoelectric 2 generator assembly can be used to power the 3 apparatus at 12 volts and 0.5 amps. Preferably four 4 thermoelectric generators connected in series are used. 6 7 The exterior end of the first suction means can be 8 oriented in any direction suitable for the drawing 9 in of insects. Preferably the exterior end of the first suction means is oriented in an upwards 11 direction. Insects are preferably drawn into the 12 apparatus through a suction pipe. 13 14 The exterior ends of both the suction and exhaust pipes are most preferably oriented in an upwards 16 direction. 17 18 Further, the entrance port of the suction pipe and 19 the exit port of the exhaust pipe are preferably located proximal to each other. 21 22 The portion of the suction pipe that extends 23 exterior to the apparatus preferably envelops the 24 exterior portion of the exhaust pipe. This portion of the suction pipe may optionally take the form of 26 a funnel shape where it envelops the exhaust pipe. 27 28 The interior end of the suction pipe is preferably 29 enclosed in the retaining means. 31 Preferably the retaining means is a capture bag or 32 the like. The capture bag is preferably disposable. 13 1 2 A further advantage of the present apparatus is that 3 heat from the gas combustion is retained within the 4 apparatus such that trapped insects are killed and become desiccated. The temperature in the vicinity 6 of the insect retaining means is generally 10°C 7 above ambient temperature when the apparatus is in 8 operation. Killed and desiccated insects can thus 9 be removed easily and hygienically from the apparatus, eliminating the possibility that the 11 insects may escape and/or inflict further bites. 12 13 The insects trapped by the apparatus are any 14 haematophagous insects. According to one embodiment of the invention, the insects are from the family 16 Ceratopogonidae, preferably midges. According to an 17 alternative embodiment of the invention, the insects 18 are mosquitoes. 19 Additional Features 21 Preferably the trapping apparatus can further 22 include a safety mechanism which maintains a safe 23 operating temperature. 24 The safety mechanism preferably includes a safety 26 valve, a safety valve button, a thermocouple and a 27 bimetallic switch. The safety valve, safety valve 28 button, thermocouple and bimetallic switch are 29 preferably connected in a circuit. 31 The safety valve controls the flow of gas into the 32 combustion chamber. The thermocouple is preferably 14 1 located such that it detects the temperature of the 2 combustion chamber and the temperature of the 3 chamber housing the catalyst. When the temperature 4 differential between the two chambers is sufficiently high, a voltage flows along the 6 thermocouple to maintain the safety valve in its 7 open position. If the temperature in the combustion 8 chamber drops or the catalyst malfunctions, the 9 valve closes, thus preventing gas entering the combustion chamber. 11 12 The bimetallic switch is preferably located on the 13 outer wall of the combustion chamber and is 14 connected in circuit with the safety valve such that if the trapping apparatus overheats the safety valve 16 closes. The trapping apparatus is deemed to have. 17 overheated when the temperature of the outer wall of 18 the combustion chamber exceeds 120°C. 19 The apparatus may further include a multispark 21 igniter. This is an electronic battery operated 22 device. On depression it provides a continuous 23 spark to the combustion chamber so as to ignite the 24 gas/air fuel mixture. 26 The apparatus may also include a voltmeter or other 27 voltage indicator to provide a visual reading of the 28 power generated by the thermoelectric generators. 29 For example, a red colour on a power indicator may show that the apparatus is warming up whilst a green 31 colour could indicate that the apparatus is fully 32 operational. 1 2 At least one exhaust vent may be provided in the 3 walls of the combustion, chamber so as to allow for 4 free movement of the air drawn in by the fans. This aids the suction of air and facilitates maintenance 6 of a continuous air speed, for example approximately 7 11 km/h. Such an air speed helps prevent the 8 entrance of insects into the combustion mechanism. 9 The apparatus may also be used merely for attracting 11 insects. 12 13 According to a second aspect of the present 14 invention, there is provided an insect trapping apparatus including: 16 a source of carbon dioxide 17 an exhaust means from which the carbon dioxide 18 is exhausted in an upward direction; 19 a suction means for drawing air into the apparatus and being adequate to allow the ingress of 21 insects contained within the air, the insects being 22 drawn into the apparatus at an area proximal to the 23 area from which gas is exhausted; 24 means for retaining the insects which are drawn into the apparatus; and 26 a top shield for reducing dissipation of gas 27 exhausted from the apparatus, wherein the top shield 28 is positioned in spaced relationship above the 29 exhaust means. 16 1 Preferred features of each aspect of the invention 2 are as for each other aspect, mutatis mutandis 3 unless the context demands otherwise. 4 Figures 6 An embodiment of the invention will now be 7 described, by way of example only, with reference to 8 the following drawings which are not intended to be 9 construed as being limiting on the present invention, wherein: 11 Figure 1 shows a side view of the upper part of 12 the trapping apparatus; 13 Figure 2 shows a perspective top view of the 14 trapping apparatus; Figure 3 shows a front view of the combustion 16 chamber and heat sink of the trapping apparatus; 17 Figure 4 shows a cross section of the front 18 view of the combustion chamber and heat sink along 19 line A-A in the direction shown in Figure 3; Figure 5 shows a schematic of the upper part of 21 the apparatus of the invention (A) and a table of 22 measurements (B) of carbon dioxide concentrations 23 and temperatures taken at six specific areas shown 24 on the schematic; and Figure 6 shows a schematic (A) of the 26 combustion chamber and the exhaust and suction 27 pipes, with an enlarged view (B) of the components 28 of the combustion chamber. 29 The trapping apparatus 10 has a combustion chamber 31 12 housing a chamber 14 which contains a catalyst 32 54. A thermocouple 16 is located inside the 17 1 combustion chamber 12 and is in contact with the 2 catalyst chamber 14. A spark igniter 18 is also 3 located inside the combustion chamber 12. The base 4 of the combustion chamber 12 is mounted on a venturi arrangement housed within a nozzle housing 20. A 6 jet carrier 24 is located at the base of the nozzle 7 housing 20. A gas nozzle 22 is also provided at the 8 base of the combustion chamber 12. A sintered disc 9 (not shown) is located between the gas nozzle 22 and the combustion chamber 12. 11 12 An exhaust chimney 26 houses an inner exhaust pipe 13 28. The thermoelectric generators 30 are arranged 14 between the outer wall of the combustion chamber 12 and a heat sink 32. A heat plate 56 is used in 16 conjunction with heat transfer pins 58 to assist in 17 thermal conductivity of the heat generated from 18 combustion to the hot side 48 of the thermoelectric 19 generators 30. The heat pins 58 are provided above and below the catalyst 54 to ensure effective heat 21 transfer through to the heat plate 56 and thus to 22 the thermoelectric generators 30. The high thermal 23 conductivity of the cast aluminium combustion 24 chamber 12 further assists in heat transfer to the thermoelectric generators 30. 26 27 The heat plate 56 is generally made of aluminium but 28 may be made from copper. It is generally 29 approximately 3mm thick. 31 The combustion chamber 12, thermoelectric generators 32 30 and heat sink 32 are housed in a first outer 18 1 housing 34. A capture chamber (not shown) is 2 located inside the first outer housing 34. An outer 3 suction pipe 36 extends from the top of the first 4 outer housing 34 into the capture chamber and envelops the exhaust chimney 26. The portion of the 6 suction pipe 36 which extends exterior to the 7 apparatus 10 forms a funnel shape 36A. A vapour 8 shield (anti-dispersal means/top shield) 38 is 9 mounted above the inner exhaust pipe 28. 11 A door 40 leading to the capture chamber is provided 12 on the first outer housing 34. A service panel 42 13 is also provided on the first outer housing 34. A 14 multi-spark ignition switch 44 is situated on the service panel 42. An air vent 66 is also located in 16 the first outer housing 34. The first outer housing 17 34 is mounted on a second outer housing 46, which 18 houses a gas cylinder (not shown). 19 2 0 The trapping apparatus 10 as shown in Figures 1 and 21 2 is mounted on wheels 50. 22 23 In use, a gas cylinder (not shown) is housed within 24 the second outer housing 46. A safety valve button 60 is activated to draw gas from the gas cylinder 26 through the nozzle 22 and sintered disc into the 27 combustion chamber 12. The venturi arrangement 28 simultaneously draws air into the combustion chamber 29 12. The ignition switch 44 is depressed, activating 3 0 the spark igniter 18 and causing the gas and air 31 mixture to ignite. A temperature differential thus 32 builds up between the combustion chamber 12 and the 19 1 heat sink 32. The gas mixture burns until the 2 oxygen in the air is used up and the catalyst 54 3 reaches its working temperature of 350 °C (measured 4 on the top surface of the active catalyst; the temperature of the inside of the catalyst can reach 6 up to 800°C). The gas is now burnt completely by 7 catalytic conversion producing steam and 8000 - 8 10000 ppm carbon dioxide at 190 °C (i.e. at the 9 exhaust chimney 26, directly above the combustion chamber 12) . A power indicator 68 indicates that 11 the apparatus has reached this stage. 12 13 When the temperature differential between the 14 combustion chamber 12 and the catalyst chamber 14 is sufficiently high, the thermocouple 16 produces a 16 voltage which holds the safety valve open. The 17 temperature differential is sufficient when a 18 voltage of 5 millivolts is generated. The safety 19 valve button 60 may then be deactivated. 21 The heat from the operational catalyst 54 is 22 transferred via the heat pins 58 and plates 56 23 through the walls of the combustion chamber 12 to 24 the thermo-electric generators 30, which are connected to an electrical output and which convert 26 the temperature differential between the combustion 27 chamber 12 and the heat sink 32 into a voltage which 28 is used to drive the inlet and outlet fans 62,64. 29 The voltage required to activate the fans is approximately 3 volts. The inlet fan 62 helps 31 maintain the temperature differential between the 32 combustion chamber 12 and the heat sink 32. 1 2 The outlet fan 64 mixes the carbon dioxide produced 3 from combustion and the air drawn in through the 4 second suction means, and forces the mixture up the inner exhaust pipe 2 8 and out through the exhaust 6 chimney 26. The carbon dioxide/water vapour/air 7 mixture leaves the exhaust chimney 26 at a 8 concentration of 800 to 5000 ppm carbon dioxide and 9 at a temperature in the region of 10 to 15 °C above ambient temperature, ambient temperature being 11 between 15 to 25 °C, for example 2 0 to 22 °C. 12 13 A cartridge 52 containing an insect attractant, such 14 as octenol, is placed at the exit of the inner exhaust pipe 28. When octenol evaporates from the 16 cartridge 52, it mixes with the carbon dioxide/water 17 vapour/air mixture, forming an insect-attracting 18 vapour. 19 The warmth of the carbon dioxide mixture causes the 21 gaseous mixture to rise up from the exit port of the 22 exhaust pipe 28. As described supra, such plumes of 23 attractant are vulnerable to dissipation caused by 24 air currents such that insects are not optimally attracted. 26 27 However, the vapour shield 38 of the present 28 invention inhibits the attractant vapour from 29 dissipating from the local vicinity of the trapping 3 0 apparatus 10. The downwardly curved peripheral 31 edges and the location of the vapour shield 38 above 32 the exit port help protect the carbon dioxide 21 1 attractant mixture from surrounding air currents. 2 The concentration and temperature of the carbon 3 dioxide mixture are thus reliably maintained at 4 known and relatively constant levels, and insect trapping is optimised. 6 7 The attracted insects are drawn in by the inlet fan 8 62 through the outer suction pipe 36 into the 9 capture bag (not shown). Once the capture bag is sufficiently full, the bag may be detached from the 11 interior end of the suction pipe 36, sealed and 12 disposed of. The capture bag is generally 13 sufficiently full when it is half to three quarters 14 full of insects. 16 Figure 5 shows the results of a test conducted to 17 determine the efficacy of the vapour shield 38 and 18 apparatus design in retaining the mixture of carbon 19 dioxide, water vapour and air in the local vicinity of the suction means. Measurements of temperature 21 and carbon dioxide concentration were taken. The 22 ambient carbon dioxide concentration was measured as 23 600 parts per million (ppm), and the ambient 24 temperature as 22 °C. Measurement 1 was taken 100mm above the attractant container 52. 26 27 The output velocity from the exhaust pipe 28 was 28 measured at point (i) in Figure 5 as 1.9 miles per 29 hour (mph) (3.2 kilometres per hour (km/h)), and the suction velocity of the suction pipe 36 was measured 31 at point (ii) in Figure 5 as 3.3 mph (4.8 km/h). 32 22 1 As can be seen from the results shown in the table 2 in B of Figure 5, the vapour shield 38 was effective 3 at retaining advantageous carbon dioxide 4 concentrations and temperatures in the local vicinity of the suction pipe 36. These carbon 6 dioxide concentrations and temperatures are thought 7 to be optimal for insect attraction and thus the 8 efficiency of the apparatus is improved. 9 It will be understood by one skilled in the art that 11 various modifications and variations may be made to 12 the invention as herein described without departing 13 from the scope of the invention. Although the 14 invention has been described in connection with specific examples, it should be understood that the 16 invention as claimed should not be unduly limited to 17 such examples. For example, the chemical attractant 18 may be replaced by any chemical attractant commonly 19 known in the field. The capture bags may optionally contain an insecticide. 23

Claims (30)

WHAT WE CLAIM IS: ■

1. An insect trapping apparatus including: a source of carbon dioxide; 5 an exhaust means from which the carbon dioxide is exhausted in an upward direction; a suction means for drawing air into the apparatus and being adequate to allow the ingress of insects contained within the air, the insects being drawn into the apparatus at an area proximal to 10 where the gas is exhausted from the apparatus in an upward direction; means for retaining insects which are drawn into the apparatus; and at least one anti-dispersal means for reducing dissipation of gas exhausted from the apparatus, wherein the anti-dispersal 15 means is in concentric arrangement above the exhaust means.

2. An apparatus as claimed in claim 1 wherein the exhaust means is adapted to direct the exhausted carbon dioxide towards the anti-dispersal means. 20

3. An apparatus as claimed in claim 1 or claim 2 wherein the exhaust means includes an exit port through which the carbon dioxide is exhausted. 25

4. An apparatus as claimed in claim 1 to claim 3 wherein the anti-dispersal means is in spaced arrangement with the exit port.

5. An apparatus as claimed in any preceding claim wherein the anti-dispersal means is concave towards the exit port. 30 INTELLECTUAL PROPER! OFFICE OF N.Z 2 0 MAR 2007 RECEIVE I 24

6. An apparatus as claimed in any preceding claim wherein the anti-dispersal means is composed of at least one carbon dioxide retaining member extending around the exit port and thus defining a carbon dioxide retaining area. 5

7. An apparatus as claimed in claim 6 wherein the carbon dioxide retaining member is a series of flanges projecting outwardly from the apparatus. 10

8. An apparatus as claimed in claim 7 wherein each flange projects outwardly from a side of a planar hexagonal plate at an angle such that the carbon dioxide retaining area is defined around the exit port. 15

9. An apparatus as claimed in any preceding claim wherein the source of carbon dioxide is combustion of a mixture of gas and air.

10. An apparatus as claimed in claim 9 wherein the combustion takes place in the presence of a catalyst. 20

11. An apparatus as claimed in claim 10 wherein the catalyst is a platinum-coated monolith block.

12. An apparatus as claimed in any of claims 9 to 11 wherein the gas is 25 propane, butane or a suitable mixture thereof.

13. An apparatus as claimed in any preceding claim wherein the carbon dioxide is mixed with air prior to being exhausted through the exit port. 30 INTELLECTUAL PROPERTY OFFICE OF N.Z. 2 0 MAR 2007 R E CEIVED 25 10

14. An apparatus as claimed in claim 13 wherein the air which is mixed with the carbon dioxide is drawn in by a further suction means.

15. An apparatus as claimed in any preceding claim wherein the carbon dioxide is exhausted as a mixture of carbon dioxide, air and water vapour.

16. An apparatus as claimed in any preceding claim wherein an insect attractant is added to the carbon dioxide prior to its exhaustion.

17. An apparatus as claimed in any preceding claim wherein the carbon dioxide is exhausted at a concentration of between 500 to 10000 ppm. 15

18. An apparatus as claimed in claims 1 to 16 wherein the carbon dioxide is exhausted at approximately 4600 ppm.

19. An apparatus as claimed in any preceding claim wherein the carbon dioxide is exhausted at between 22 °C to 45 °C. 20

20. An apparatus as claimed in claims 1 to 18 wherein the carbon dioxide is exhausted at between 24 °C to 42 °C.

21. An apparatus as claimed in any preceding claim wherein the carbon 25 dioxide is exhausted at a velocity of between 3 to 3.5 km/h.

22. An apparatus as claimed in any preceding claim wherein the carbon dioxide is exhausted from an exhaust pipe. INTELLECTUAL PROPERTY OFFICE OF N.Z. 2 0 MAR 2007 RECEIVED 26 10

23. An apparatus as claimed in claim 22 wherein the exterior end of the exhaust pipe is oriented in an upward direction.

24. An apparatus as claimed in claim 22 wherein the exterior end of the exhaust pipe is adapted to be directed towards the anti-dispersal means.

25. An apparatus as claimed in any preceding claim wherein the suction means includes at least one fan and a suction pipe.

26. An apparatus as claimed in claim 25 wherein the exterior portion of the suction pipe is located proximal to the area where gas is exhausted from the exhaust means. 15

27. An apparatus as claimed in claim 25 or 26 wherein the portion of the suction pipe exterior to the apparatus envelops the exterior portion of the exit port through which carbon dioxide is exhausted.

28. An apparatus as claimed in claim 27 wherein the exterior 20 enveloping portion of the suction pipe is substantially funnel- shaped.

29. An apparatus as claimed in any one of claims 25 to 28 wherein the interior end of the suction pipe is connected to the retaining means. 25

30. An apparatus as claimed in any preceding claim wherein the suction rate of the suction means is between 4.5 to 5.5 km/h. INTELLECTUAL PROPERTY OFFICF OP N.Z. 2 0 MAR 2007 RECEIVED 27 32. 5 15 33. An apparatus as claimed in any preceding claim wherein at least one air vent is provided in the walls of the apparatus. An insect trapping device including: a source of carbon dioxide; an exhaust means from which the carbon dioxide is exhausted in an upward direction; a suction means for drawing air into the apparatus and being adequate to allow the ingress of insects contained within the air, the insects being drawn into the apparatus at an area proximal to the area from which gas is exhausted; means for retaining insects drawn into the apparatus; and a top shield for reducing dissipation of gas exhausted from the apparatus, wherein the top shield is positioned in spaced concentric relationship above the exhaust means. An insect trapping apparatus substantially as hereinbefore described with reference to the accompanying drawings. An insect trapping apparatus as claimed in claim 1 and substantially as herein described with reference to any embodiment disclosed. TEXOL PRODUCTS LTD .orised agents INTELLECTUAL PROPERTY OFFICE OF N.Z 2 0 MAR 2007 RECEIV E D