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.2.1.3 The material collected during cleaning should bedisposed of, or treated, immediately so that the insects cannotescape and spread to other parts of the ship or elsewhere.Inport it may be burnt or treated with a pesticide, but in manycountries such material may only be landed under phytosanitarysupervision.Where destruction ashore is not practicable, thesweepings should be jettisoned well out to sea.If any part ofthe ship is being fumigated the material may be left exposed tothe gas.2.2 Main sites of infestation2.2.1 Tank top ceiling: If, as often happens, cracks appearbetween the ceiling boards, food material may be forced down intothe underlying space and serve as a focus of infestation for anindefinite period.Insects bred in this space can readily moveout to attack food cargoes and establish their progeny in them.2.2.2 'Tween-deck centre lines, wooden feeders and bins areoften left in place for several voyages and because of theirconstruction are a frequent source of infestation.Afterunloading a grain cargo, burlap and battens covering the narrowspaces between the planks should be removed and discarded beforethe holds are cleaned or washed down.These coverings should bereplaced by new material in preparation for the next cargo.2.2.3 Transverse beams and longitudinal deck girders whichsupport the decks and hatch openings may have an L-shapedangle-bar construction.Such girders provide ledges where grainmay lodge when bulk cargoes are unloaded.The ledges are oftenin inaccessible places overlooked during cleaning operations.2.2.4 Insulated bulkheads near engine-rooms: When the holdside of an engine-room bulkhead is insulated with a woodensheathing, the airspace and the cracks between the boards oftenbecome filled with grain and other material.Sometimes theairspace is filled with insulating material which may becomeheavily infested and serves as a place for insect breeding.Temporary wooden bulkheads also provide an ideal place for insectbreeding, especially under moist conditions, such as when greenlumber is used.2.2.5 Cargo battens: The crevices at the sparring cleats areideal places for material to lodge and for insects to hide.2.2.6 Bilges: Insects in accumulations of food material areoften found in these spaces.2.2.7 Electrical conduit casings: Sometimes the sheet-metalcovering is damaged by general cargo and when bulk grain isloaded later, the casings may become completely filled.Thisresidual grain has often been found to be heavily infested.Casings that are damaged should be repaired immediately or, wherepossible, they should be replaced with steel strapping, which canbe cleaned more easily.2.2.8 Other places where material accumulates and whereinsects breed and hide include:The area underneath burlap, which is used to cover limberboards and sometimes to cover tank top ceilings.Boxing around pipes, especially if it is broken.Corners, where old cereal material is often found.Crevices at plate landings, frames and chocks.Wooden coverings of manholes or wells leading todouble-bottom tanks or other places.Cracks in the wooden ceiling protecting the propeller shafttunnel.Beneath rusty scale and old paint on the inside of hullplates.Shifting boards.Dunnage material, empty bags and used separation cloths.Inside lockers.3 Chemical control of insect infestation3.1 Methods of chemical disinfestations3.1.1 Types of pesticides and methods of insect control3.1.1.1 To avoid insect populations becoming firmly establishedin cargo spaces and other parts of a ship, it is necessary to usesome form of chemical toxicant for control.The materialsavailable may be divided conveniently into two classes: contactinsecticides and fumigants.The choice of agent and method ofapplication depend on the type of commodity, the extent andlocation of the infestation, the importance and habits of theinsects found, and the climatic and other conditions.Recommended treatments are altered or modified from time to timein accordance with new developments.3.1.1.2 The success of chemical treatments does not lie whollyin the pesticidal activity of the agents used.In addition, anappreciation of the requirements and limitations of the differentavailable methods is required.Crew members can carry outsmall-scale or "spot" treatments if they adhere to themanufacturer's instructions and take care to cover the whole areaof infestation.However, extensive or hazardous treatmentsincluding fumigation and spraying near human and animal foodshould be placed in the hands of professional operators, whoshould inform the master of the identity of the activeingredients used, the hazards involved and the precautions to betaken.3.1.2 Contact insecticides3.1.2.1 Space treatments: Insecticides may be discharged intothe air as fine particles of liquid or solid.There are a numberof types of equipment for producing and distributing suchparticles.This method of treatment kills flying insects anddeals with superficial infestation where exposed insects comeinto contact with the particles, whilst there may be a limitedresidual pesticidal effect on surfaces on which the particlessettle.3.1.2.2 For use in cargo spaces, space sprays and fogs can beproduced in several different ways.These include fog generatorsin which an insecticide in the form of a liquid or coarse sprayis vaporized.Such vaporized insecticides may condense into fineparticles on reaching cool air.Alternatively, fine particlesmay be produced mechanically from suitable formulations bydispersing nozzles, venturi systems or centrifugal force.Insecticidal smokes are evolved from generators simply byigniting the material and such generators are a convenient formof application for use by ships' personnel.3.1.2.3 Tests have shown that these insecticidal smokes andsprays can be very effective against insects moving freely in theopen, in spaces such as holds.However, no appreciablepenetration or control of insects can be obtained in deepcrevices, or between or under deck boards, tank top ceilings andlimber boards, places where infestation commonly occurs.Whereinsects are deep-seated, it is usually necessary to use afumigant.3.1.2.4 Surface sprays: Spraying with a suitable insecticidecan also be used to control residual infestation
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