Department of Health Library Services ePublications

Department of Health Library Services ePublications - Historical Collection

Please Note: Aboriginal and Torres Strait Islander people should be aware that this publication may contain images, voices or names of deceased persons in photographs, film, audio recordings or printed material.

Purpose

To apply preservation treatments, including digitisation, to a high value and vulnerable Historical collection of items held in the Darwin and Alice Springs libraries so that the items may be accessed without causing further damage to the original items and provide accessibility for stakeholders.

Reference and Research Disclaimer

Please note: this document is part of the Historical Collection and the information contained within may be out of date.

This copy is a reproduction of an original record. Please note that the quality of the original record may be poor and cannot be enhanced with the scanning process.

Northern Territory Department of Health Library Services Historical Collection

DL HIST 595.772 WHE 1987

. J

DEPARTMENT OF HEALTH AND COMMUNITY SERVICES

POTENTIAL BITING . INSECT PROBLEMS FORMER EXPLOSIVES RESERVE

LOT 4646 DARWIN

FOR MORE INFORMATION:

CONTACT: DEPARTMENT OF HEALTH AND COMMMUNITY SERVICES MEDICAL ENTOMOLOGY SECTION

G.P.O. BOX 1701 DARWIN NT 5 794 TELEPHONE : 20 8333

Peter Whelan

Senior Medical Entomologist

Oo-S~'2_

HISTORICAL COLLECTION

l l l

l

l

l

-1

I I I I l I

_j

J J J J J J

I · 1 11i1i1 l1~H1111ij1i1i1 U i i11H~ 1 !1~1l1 ~J

3 0820 00018965 9

POTENTIAL BITING INSECT

~ROBLBMS

FORMER EXPLOSIVES RBSBRVB - LOT 4646 DARWIN

MEDICAL ENTOMOLOGY BRANCH

DEPARTMENT OF HEALTH ^& COMMUNITY SERVICES

1.0 INTRODUCTION

The Darwin Regional Structure Plan 1984 indicated the potential for residential infilling or various areas between Stuart Park and Berrimah. The first proposal indicated by the Department of Lands involved the RAAF munitions area on Lot 1263. An extensive biting insect survey was conducted by the Medical Entomology Branch of the former Northern Territory Department of Health over a twelve month period in this area during 1984-85. The Department of Lands has recently indicated there is a potential for residential development of the former explosives reserve on Lot 4646.

There has not been an extensive entomological investigation of this area. but the potential biting insect problems has been outlined from an examination of the area. the available entomological data. and by comparison with the extensive investigations on Lot 1263.

2. 0 Mosquitoes

There are only moderate numbers of mosquitoes in the vicinity of Lot 4646. The main sources of mosquitoes in this area are associated with the drainage line from Bishop Street, through the explosives reserve, to the mangroves.

This drain receives waste water from the Bishop Street industrial area, and the lower reaches are extensive and i l l defined, with surface water remaining in the dry season.

This drainage would need complete formalization to an end point in the mangroves of at least the 3.0 AHD level. There are other potential mosquito breeding sites that could be inadvertently created by interference with the mangrove vegetation and drainage lines during construction. The Coastal Management Technical Advisory Committee has prepared guidelines for construction practices near mangroves.

CENTRAL LIBRARY

TERRITORY HEALTH SERVICES·.

PO BOX 40596

I

t

CASUARINA NT 0811

1

3. 0 Biting Midges

3. 1 Overview

A general outline of the relevant characteristics of biting midges can be found in Appendix I. Further discussion can be found in "Mosquito and Biting Midge Investigations Palmerston 1982-85" prepared for the Palmerston Development Authority. The mangrove fringe east of Stuart Park, to the eastern side of Lot 4646 exhibits a low to moderate activity by biting midges. There is an increase in biting midge activity eastwards from Woolner Road to the Winnellie area.

The eastern reaches of Sadgroves Creek are major sources of biting midges. Lot 4646 has a significantly less biting midge problem when compared with Lot 1263, but would have a greater problem that the present areas of Stuart Park. The biting midge problem is regarded as significant and the area is unsuitable for residential development unless various engineering solutions can be found to reduce the problem.

3. 2 Biting Midge investigations of Lot 1263

The results of the investigations of biting midges on Lot 1263 are shown on Table 1. The location of the trapping sites are found on Map 1. The figures on Table 1 are the number of Culicoides (biting midges) caught per trap night using a special dry ice baited, battery operated, modified CDC mechanical suction trap. The trap sites were selected for proximity to the mangroves and at various distances from the mangroves, and operated from one < 1 > hour before sundown to two C ²⁾ hours after sunrise. The traps were run either at or close to the time of the neap or spring tide during the mid dry, late dry. early wet and late wet - early dry seasons. The number of biting midges were estimated by volume comparisons with known sample sizes and examination of selected samples indicated the majority of the midges were Culicoides ornatus.

The investigations revealed a number of important points that have a bearing for residential development of Lot 4646.

The major findings of the investigation are listed below:

Ca) There are higher numbers of biting midges in the south east corner of the study area, decreasing in number to the north west and north east.

( b)

( C)

There appear to be significantly less numbers of midges on Lot 4646 than Lot 1263.

The biting midges are more numerous on top plateau near the widest expanse of mangroves, with sites at the immediate landward edge mangroves.

2

biting

of the compared of the

1 l l . l l l . l l

I

I

J

J

J J J J J J

Cd) The highest number of biting midges were found associated with the times of the neap tides but, in most seasons, except· for the 1 ate dry seas on, there we re only slightly higher numbers found at the times of the neap tides when compared with the times of the spring ti des .

Ce) The number of biting midges shows a reduction with distance from the mangroves, with significant reductions from about one hundred metres (100m) from the landward mangrove margin towards the point one and one half kilometres <1. 5km) from the nearest mangroves.

< f) At those times of the year with the highest activity,

biting midges are significant pest problems at least one and one half kilometres (1.5km) from the nearest mangrove margin .

3. 3 Potential Biting Midqee Problems on Lot 4646

Although the potential biting midge problems on Lot 4646 are expected to be significantly less than on the adjoining Lot 1263, the trap catches of up to 4000 midges per trap night on Lot 4646 during October indicate that biting midges will poses a significant problem for residential development.

For comparison, catches of a few hundred biting midges in Stuart Park, Larrakeyah and The Narrows area can result in public complaints and calls for biting midge control.

This area has extensive potential biting midge breeding areas on three sides when compared with the relatively narrow, single boundary for Stuart Park, so the potential problems are expected to be of a higher magnitude and for more extended periods. Advantageous winds to reduce the activity and dispersal of biting midges would be less frequent in this area than in Stuart Park.

The investigations on Lot 1263 indicate that the biting midge numbers could very likely be more numerous on top of the plateau in this area compared with closer to the mangroves, so a 1 OOm buffer between the mangroves and residential development would probably offer l i t t l e relief.

As the eatern side of Lot 4646 is closer to the extremely high levels of biting midge activity between Sadgroves Creek and Reichardt Creek, the biting midge activity is expected to be greater on the eastern side compared with the western side.

The Medica~ Entomology Branch has outlined a number of considerations covering biting insects and urban development and these are attached as Appendix II.

The satisfactory control of larval and adult biting midges in this area by insecticidal means would not be practical. The only method currently available to reduce the numbers of midges within the area would be to f i l l in or flood the present neap tide zone of the mangroves. This would mean that most of the western side of the Reichardt Creek mangrove area would need to be destroyed. An alternative

3

approach could be to develop the residential area and wait for public reaction until tackling the biting midge problem, but this may be unacceptable from both a marketing and practical viewpoint.

4.0 Conclusion

1. Biting midges on Lot 4646 will pose a significant problem with residential development.

2. Insecticidal control of both the larval and adult stages of biting midges in this area is impractical.

3. The removal or reduction of the biting midge problem would necessitate removal of the neap tide zone around the boundary of the entire area. As a less effective solution, significant reduction could be achieved by only removing the mangrove boundary at the eastern side, as long as there is a significant distance of open water between the residential development and other mangrove areas.

Peter Whelan

Senior Medical Entomologist

NT Department of Health & Community Services 25/3/87

4

1

uu..;, :::> ·/-;{_.

Table 1 BITING ~ID6E COLLECTIONS - RAAF ~UNITIONS RESERVE/LOT 1263, DARWIN - 1984-85

l

NEDICAL ENTONOL06Y BRANCH

Total nu1ber of Culicoides collected in CO2 baited traps per trap night

l

TRAP SITE 23.5.84 27.6.84 4.7.84 9 .10.84 17.10.84 15 .1.85 22.1.85 24.4.85 3.5.85 TOTALS AVERAGE/ TRAP NI6HT

l

2 ³⁷⁵⁰ 500 ²⁸⁰⁰ 1800 ²⁴⁰⁰ 450 ³³⁰⁰ 13000 ²⁵⁰⁰ 350 ⁴⁸⁰⁰ 1200 ²⁰⁰ 450 ⁷⁵ 140 ^{FAIL 11} 2000 ¹⁹⁸²⁵ 19890 ²⁴⁷⁸ 2210

l

^{3 250 11 250 250}

4 7300 2300 150 17700 250 800 100 3200 3600 35400 3933

l

^{5 3900 It 3900 3900}

.l

⁶ 7 ⁶⁶⁰⁰ 2700 ³⁵⁰⁰ 700 ⁴⁸⁰⁰ 1000 ²⁵⁵⁰⁰ 14600 ⁵⁰⁰ 950 ⁴⁷⁰⁰ 1500 ²⁰⁰ 1700 ⁵⁰⁰ 120 ²³⁰⁰ 3100 ⁴⁸⁶⁰⁰ 26370 ⁵⁴⁰⁰ 2930

l

⁸ _{9 1500} ^{2000 It} _{FAIL 12 1000 5000 1800 1250 1900 FAIL 1800 14250} ^{2000 2000} ₂₀₃₆

l

^{10 FAIL 11}

i1 90 100 1500 11300 300 80 30 t 20 4300 17820 1 '~80

I

^{12 250 11 250 2~/)}

l

¹³ ₁₄ ¹²⁰⁰ ₁₄₆₀₀ ²⁰⁰⁰ ₁₂ ^{650 24600 3400 2300 3200 3500 800 46650 5183}

· · i

^{i. 89400 15100 5000 11700 30(!(1 3(H) 139600 1'1943}

j

^{WEST 12}

•..

^{i. , 12 4000 1200 3200 1000 500 650 10550 17~::3}

EAST 12 12 12 36550 4200 1100 1000 ^6(H) 1000 44450 7408

J

^{TOTALS 44640 13200 11950 244950 35550 25930 21480 11755 20350 429805}

J

^AYERA6E/ TRAP/NONTH ^{3433 1886 1494 22268 3232 2357 1953 1175 2035}

J

DATES OF SPRIN6 AND NEAP TIDES IN ASSOCIATION WITH TRAPPING NI6HTS

NEAP TIDE 25.4.84 23.6.84 4.10.84 15 .1.85 30.4.85

J

SPRING TIDE 1. 7 .84 12.10.84 22.1.85 22.4.85

11 Trap failed - 3800 dead Culicoides retaining in trap

J

+2 Trap failed - 2400 dead Culicoides retaining in trap 11 Trap site not used again

12 Trap site not used

J

J

I

•

(

\

i

LEGUW Roads TrcJ.cks Trap site

i.il TING INSECT SURVEY - RAAF :-:c:rT:ONS RESEP.VE/L01 :i..2G3, DARv-JHi Sc1r.1pling sites for CO2 bai tl-'!0 i nsec:t traps.

0 500 1000 1500

SCALE IN HL'l RES

.-^.:.~

Map l N

t

.- -:: -~-,.:. ^{~ t,.~euiga,J} Lntomolor:,;~- Bra

N'~ I-iEALTll

. ^~ -....

t

)

l l

I

1

J

J

_J

J

J

J

J J J

BITING MIDGES OR SAND FLIES-IN DARWIN NORTHERN TERRITORY DEPARTMENT OF HEALTH

1.0 BITING MIDGES

Biting midges are small blood sucking flies, and are commonly referred to locally as "sand flies". The term "sand fly" is a misused term in common usage for any small biting flies, which includes the true sandfly (Phlebotomus), which are not a local pest, as well as black flies ( Simulium), which are serious pests in the interior of the eastern states. In the coastal areas of the Northern Territory, the true biting midges of the family Ceratopogonidae are the major midge problem. There are a number of members of this family which bite people in the Darwin area but the most common are the Culicoides group of species. Two species, Culicoides immaculatus and Culicoides ornatus are the ones frequently referred to as "sand flies" 1.n the Darwin area, and are the ones that turn out to be the culprits whenever there is a biting midge problem. Culicoides immaculatus is a minor problem as it is found in lower numbers and is only common near open sandy foreshores, while Culicoides ornatus, which is associated with certain areas of mangrovesi 1.s a major pest, as it breeds in very high numbers and commonly affects nearby residential areas.

Bi ting midges are very small, robust flies, with two wings showing a pattern of clear patches. They have a short, forward directing proboscis or mouthparts. They are approxi- mately 1 mm in length so they are visible to the naked eye.

The fact that their bite goes unnoticed in many people, until a reaction occurs, has led to the idea that they are too small to be seen. These insects are becoming an increasing problem in Darwin due to urban development nearer to their breeding places. Culicoides ornatus poses problems due to their extremely annoying and painful bites, and to the discomforting after-effects of their bites.

In tropical cities such as Darwin, evening outdoor recreation is an important aspect of the quality of life, and these insects can impose serious restrictions on these recreational activities.

2.0 BITES OF BITING MIDGES

It is only the female which bites. They must take a blood meal in order for their eggs to mature. They do not, as is sometimes believed, urinate on people to cause discomfort. In the process of biting and sucking blood, they inject a salivary secretion which produces a skin reaction of varying intensity, depending more on the individuals reaction than on the species of the midge. There is the classic allergic response with the first bite producing no noticeable effect and then the subsequent bites, at a later time, producing 14.ll[B]

2

severe reactions. If the exposure to midges is reasonably continuous, a process of desensitization may follow so that eventually only very mild reactions occur. Usually residents of long standing and continuously exposed are tolerant to the bites. They don't get a reaction or itch while some new comers, particularly women and children, are seriously distressed.

The actual bite from a midge may be painless to newcomers, al though people with continuous exposure do detect penetra- tion. The average reaction is delayed for 6 to 24 hours after the bite has taken place. The minium reaction is a point of redness at the site of the bite, which is only mildly discom- forting and lasts only an hour after bi ting. The average reaction is to produce a small dome shaped blister that has a

hole at the top. This is extremely itchy and scratching is very difficult to avoid. This reaction may last 3 - 4 days with decreasing irritation. Such reactions require little treatment other than the soothing lotions such as Eur ax.

Increasingly severe and larger reactions may need medical advice. Sometimes the scratching produces secondary infections. In certain people who are sensitive, the site of the bite may not be obvious and the reaction may result in a red swelling over an area of a few centimetres.

3.0 BREEDING SITES OF CULICOIDES ORNATUS

This is by far the most common biting midge pest in the Darwin area. It breeds in the muddy shoreline, completely sheltered from wave action. It is usually under dense tree cover, in association with certain species of mangroves. There is a close association of breeding with the occurrence of two mangrove species (Aegiceras corniculatum and Rhysophora stalosa). The eggs are laid in the narrow zone near neap high ti e level and the larvae when hatched out are small active wormlike creatures that are confined to the mud in the zone near neap high tide level. The larvae take in excess of

6 weeks to develop until they change into a relatively inactive, air breathing pupa. The pupal stage lasts only a

period of several days and the adults emerge about the time of neap tides.

4.0 THE HABITS OF CULICOIDES ORNATUS

This species bites typically during the hours around sunrise and sunset, but will continue to bite throughout a still, humid day and warm humid night, while it will bite at almost any time within proximity to its breeding area.

In wind above 8 km/hour they seek shelter so that there is little tendency for them to be borne long distances by strong winds, although light breezes from their breeding areas will aid their flight. They are active fliers and despite their small size, are relatively hardy animals. The high numbers of adults is related to the lunar. cycle, with sudden rises of the order of 16 times occuring at neap tide, with the peak in numbers, one day either side of the neap high tide. High 14.ll[B]

l l l . l l l .l

l l l I I

J

J J J J

3

numbers will continue up to 4 days after neap tides. The adults are most numerous in mangroves penetrated by narrow creeks. Mass movements of adults can occur from \ to 1 km from their breeding sites, al though they will move greater distances up vegetated rivers of dense tree cover and high humidity. These creeks, from their breeding sites in the mangroves, form avenues of sandly activity .

5.0 PROTECTION FROM BITES 5.1 Avoidance

Bi ting midges bite in the early morning or late afternoon around sunrise and _sunset. Attacks occur in the day time near breeding areas or in dense vegetation that is continuous with the mangrove areas near the breeding place. Areas that are close to the mangroves, especially near densely vegetated creeks that run into the mangroves, should be avoided, and this particularly applies at times of neap tides.

Biting is active under calm conditions and inhibited by wind, so that wind protected areas near the mangroves should be avoided during the neap tide. If there is an open area that is exposed to winds and up to 1.6 km in width from the breed- ing areas~ then this will provide a buffer zone against heavy invasion of bi ting midges. As a minimum requirement in the Palmerston development area, it is recommended that a biting midge buffer zone of 1 km be implemented, as the area i s particularly bad for biting midge activity.

The worst affected areas around Darwin include the Buffalo Creek area, Sandy Creek area, and Ludmilla Creek area. The north shore of Frances Bay near Sadgroves Creek are particu- larly troublesome areas, as well as areas of Leanyer Swamp and the northern mangrove margins.

Darwin city itself is relatively free from midges due to the lack of mangroves, the exposed _cliffs, and the SE and NW winds do not blow from mangrove areas.

5.2 Clothing and Netting

If people do enter areas of high midge numbers they should be adequately protected by full length trousers and shirts. Any exposed part of the body, will be subject to midge bites.

Areas of particular concern are the legs where most bites occur. Mud can be applied as an emergency measure but midges will bite through thin smears of mud so the mud must be thick and even over exposed areas. Usually insect nets and screens are not adequate to restrict entry to midges unless the mesh is very fine.

14.ll[B]

4

5.3 Repellants

Repellants have limitations because of their short duration of effectiveness (about 4 hours) and their irritability to mucous membranes such as the eyes and mouth. Young children are difficult to protect in this way since they inevitably spread the repellent to their eyes or mouth. Repellants are subject to being removed by perspiration in the Darwin climate which further reduces their effective period. However some protec- tion can be achieved by repellants, especially those that contain DEET ( diethyl toluamide) as the active constituent.

Repellants can also be applied to mosquito netting or insect screens al though a sample application on a small piece of netting is wise as some repellants affect synthetics. As an emergency measure, smoke from a fire with green leaves will afford some protection.

5.4 Use of Lights

Instances of large numbers of midges attracted to lights are conunon. In houses in very bad biting midge areas it is best to have dull outside lighting and little light visible from outside or to have necessary outside lights away from insect screens, as the midges would be attracted to the light and then penetrate the insect screens to bite the people inside.

Outside lights should be yellow to reduce their attractiveness to biting insects. Attractive lights such as large incandes- cent bulbs, or fluorescent tubes can be positioned a distance away from a house or building to deflect biting midges.

5.5 The Elimination of Vegetation

This removes shelter for the midges. This method is useful between mangrove breeding sites and residential development.

A buffer of clear open space, subject to winds, will reduce biting midge numbers. Mowing a wide margin around houses to eliminate dense grass will reduce the available areas where midges can harbour.

6.0 CONTROL OF MIDGES

6.1 Insecticide Spraying Against Adult Midges

Insecticide fogging operations carried out against adult biting midges in residential areas are not effective measures to eliminate pest problems, due to the rapid reinfestation of insects from outside the sprayed area. Sometimes reinvasion occurs immediately the fog has cleared, although up to 12 hours protection can be achieved in localised situations.

For effective fogging the entire midge breeding and harbouring area near residential development needs to be fogged over a three day period, and this area would have to be isolated from other such areas. In the Darwin situation these areas are too

14.ll[B]

l l l l l l

l

1

I I I l

J

J

J

5

inaccessible, too wide, or too extensive for practical elimin- ation for midges, although some temporary relief is possible in some areas.

Aerial application has given the best results in investiga- tions overseas but in some instances there has been immediate reinfestation. It is a difficult practice as the breeding grounds have to be closely delineated and fogging based on an accurate forecast of emergence times. This control is not carried out regularly overseas and in the local situation would require a lot of research and involve large continuing costs. The evaluation of whether fogging is effective is very difficult due to the midge's size and habits and as yet this problem has not been adequately solved. Insecticide resist-

ance and the killing of other insects would be potential problems.

6.2 Insecticide Control Against Larval Habitats

If the breeding or potential habitats can be recognised in midge infested areas, breeding ground treatment before emerg- ence of adults is a possibility. Again this needs consider- able research in the local situation and would involve considerable costs and organisation that would not be justi- fied over the extensive areas surrounding Darwin.

Insecticides would need to have good residual qualities and be able to penetrate mud in the tidal situation. Any insecticide with these qualities would not be recommended for environ- mental considerations of killing other animals, and insecti- cides ending up in food chains. The fact that the breeding grounds are under dense mangrove cover and inaccessible means that with aerial applications, the vegetation may prevent the correct placement of insecticide.

6.3 Elimination of Breeding Habitats

In some instances where salt marshes or mangroves have been reclaimed to prevent mos qui to breeding, it has resulted in increased problems from biting midges because the water table was still sufficiently high to enable biting midge breeding.

Any area that is so filled needs to be filled to at least

80 cm above the the water table, and this usually requires large amounts of not readily available fill.

Tides rising or f allin9 against a gently sloping shoreline resulting from reclamation will also provide potential biting midge problems, as has occurred in some of the canal develop- ments in Queensland. This is likely when the reclamation is not extended sufficiently into the tidal area. The ultimate solution in reclamation of mangrove areas is that the tide should rise and fall against a vertical wall that is extended beyond the neap high tide zone. This type of elimination of breeding areas of biting midges is not recommended unless the exact breeding sites of midges are known. In the Darwin area this solution would not be practicable because of the extens- ive areas involved, and the destruction of large areas of 14.ll[B]

6

mangroves is envirorunentally undesirable. This solution would only be practicable if the breeding site was small and 1n close proximity to residential development, and the filling of the area was creating a stable shore environment.

Before any such filling of mangrove areas is carried out it should be conclusively proven that the site to be reclaimed is a source of biting midges and that the midges are significant

~ests to nearby residential development. Mangroves can be an indicator of where bi ting midges may be breeding, but the presence of mangroves does not confirm any site as the breed-

ing place for bi ting midges as there are other specific factors involved in these sites which are still unresearched.

Peter Whelan

Senior Medical Entomologist NT Department of Health

A Northern Territory Department of Health Internal Report.

14.ll[B]

l l l l l l

1

1

1 1

I I I

J J

J

J J J

7

REFERENCES

The Australian Museum Magazine 1943, p. 210 Frank Taylor

The Biting Midge Problem, SPH & TM. Uni of Sydney, David Lee

The Coastal Sandfly Problem with Special Reference to Darwin,

SPH & TM. Uni of Sydney, David Lee

The Influence of the Tide Cycle on Certain Species of Culicoides Ceratopogonidae, Proc Linn Soc NSW 1962, Vol. 87 P & 3, E. Reye & D. Lee

A Guide to Common Queensland Biting Midges, Uni of Qld 1973, E. Reye

14.ll[B]

BITING INSECT CONSIDERATIONS FOR URBAN SUBDIVISION IN THE TOP END OF THE NORTHERN TERRITORY

Medical Entomology Branch - N. T. Health Department

There are a number of standing recommendations from the Entomology Branch to reduce potential problems from insects in proposed residential sub-divisions in the top the Northern Territory. These include:

Medical biting end of

1. A mosquito buffer zone for the exclusion of urban residential development is recommended such that there is no residential development within 1. 6 kilometres of a large and uncontrolled mosquito breeding area. This i s particularly emphasised if the mosquito breeding area is under any tidal influence, and in such cases the 1. ⁶ krn.

2.

would be an absolute mini mum recommendation. Such areas would need specific entomological investigation.

There should be no urban residential development 1km of broad expanses of mangroves or tidal rivers, entomological investigation indicates that biting are not a significant problem.

withi n unless midges

3. There · should be a certain standard for open unlined drains from urban residential de velopment! which would incl ude particular attention to the constructi on and end points of

.:1.

~ _,.

s u c h d 1' a i n s . c o n c t' e t e 1 o w

Concrete sub so1l drai ns, or open drains wi th f low capabilities are recommended for all suburban d r' a .i n s 1

ce9ular

t o an end point that 1s usuall y a large

r· 1 ·.:e c or' t i ^d a 1 a t' e a . P a r t i c u 1 a r g u 1 d e 1 i n e s a r e attached.

C e r t. a i n h e a 1 t h s t a n ct a r d s a t' e r e q u i r e d septic tanks, rainwater tanks and effluent.

f o ^1' i n st a 11 at i on of the r euse of sewage

ri' he re ·.: e t' pr a c t i cab 1 e : a s em j - r u r a 1 s u b di \' i s i on co u l d incorporated into a residential sub di vision design increase the effectiveness of a mosquito buffer zone.

be t o

6. The sub cti ~,ision bordering freshwater lagoons. waterways and tidall y affected areas should maintain a buffer distance between the highest water levels and residential boundaries so that access is possible for the management of such areas to prevent the creation of new mosquito sites.

...,

/ .

8.

All open unlined stormwater drains should have drainage easements maintenance of such drains.

in to

residential areas allow periodi c

T h e r e s h o u 1 d b e n o t' e s i d e n t i a 1 d e v e 1 o p me n t w i t h i n 1 . 6 km of actual or planned soil, sand or gravel mining operati ons, unless such areas ha~e been rehabilitiated to the s tage

\·:het'(' th0:: ar·e not pot ential mos qui to breeding sites.

l l l l l l l l

I I I

J

J

J

J

J J J J

J

9. A d '..' 1 c e o n t h c p o t e n t i a 1 b i t 1 n g 1 n s e c t p r ob 1 e ms f o t'

r e s 1 d e n t i a 1 d e v e l o p me n t s h o u 1 d b e s o u g h t f l' o m t he He a 1 t h Department at least 12 months before the detailed planning stage.

The Health Department's Medical Entomology Branch is available for advice on what may constitute a potentially significant b r e e d i n g s i t .e . I n s om e i n s t a n c e s a b r i e f i n s p e c t i o n by t he Branch may be sufficient to ascertain the necessary information for recommendations on a specific site, but in other instances longer term studies may be necessary. In some instances where detailed entomological investigations are necessary, i t may need up to 12 months entomological monitoring before the detailed

p 1 a n n i n g s t a g e , p a r t i c u 1 a r 1 .''l i f r e d u c t i o n i n t h e r' e c o mm e n d e d

buffer distances is desirable. For significant entomological necessary for the developer Consultant, with the consultant Branch.

investigations, to engage an liaising with

i t may be Entomological the Entomology

Relevant documents on the various aspects regarding are available from the Entomology Branch.

mosquitoes

Peter Whelan

Senior Medical Entomologist 1 9 8 6.

2

CENTRAL LIBRARY j

TERRITORY HEALTH SERVICES ·i

PO BOX 40596 ;,·

CASUARINA NT 0811