The Industrial Entomologist

Ed. M. Searls.

The industrial entomologist, using long-lasting insecticides and exerting full influence on the construction and operation of food-processing plants, has given the world a new conception of sanitation.

Thanks to him, preventive entomology has replaced the older practices of insect control; for the first time in man's history we can speak definitely of insect prevention. Insects used to be thought of in terms of the food they destroyed; now in factories they are considered chiefly as a major index of sanitation.

Industry has become increasingly aware of the need for avoiding and excluding insects. Even factory sites are selected with this in view. Many species of night-flying insects, readily attracted to lights and possibly troublesome in food processing, come from rivers, streams, and ponds. City dumps where refuse accumulates breed many pests and detract from the appearance and desirability of plant sites. Food processing or packing plants today are not built near such places.

Ready transportation is necessary, but smoke, soot, dust, and cinders as well as insects are associated with high-speed highways, railroads, and docks. Insect prevention and general sanitation are much easier to achieve when plants are removed from them.

Pest prevention about the plant and on the surrounding grounds is the concern also of the industrial entomologist. There must be no accumulation of waste or debris in which insects might feed and breed.

The influence of the industrial entomologist, working with the plant architect and the industrial engineer,

is readily seen in the construction of the newer plants and factories for handling food. The industrial entomologist divides the rooms of a food-processing plant into critical and noncritical. Critical rooms are those where food or food materials are exposed or where containers used for holding food are sometimes open, so that insects or airborne debris might contaminate food. Critical rooms should never open directly to the out-of-doors because there is too much danger of contamination by airborne debris, particularly insect parts, rodent hairs, and feather barbules.

Noncritical rooms are those in which food or food materials are always fully enclosed or in which no food is handled. A noncritical room should always separate a critical room from the out-of-doors.

Most of the insects and other pests of food processing gain entrance through doors and windows. Doors are probably the chief avenues of entrance. Double-swinging, fast-closing doors, properly bumpered to prevent damage, should be used whenever possible in openings to the outside. Single-acting doors or sliding doors may be required by the fire code, but when they open to the outside they should always be supplemented by the double-swinging, fast-closing doors. It is too easy (and sometimes necessary) to block open sliding or single-acting doors and leave them so, thus providing easy entrance for airborne dust, debris, and insects.

Insects enter through unscreened windows left open for ventilation. They even enter through window screens of less than 18 meshes to the inch; 20-mesh screen therefore is much better, because coarser-mesh screen permits the entrance of airborne debris. Consequently artificial illumination and designed air circulation, instead of open windows, screened or unscreened, are earnestly recommended by the industrial entomologist. Apparatus that will keep out insects will usually exclude airborne debris and help prevent unsanitary conditions.

The noncritical room, or vestibule, also serves as a place in which to open materials and supplies used in food processing. Corrugated paper or other types of boxes and packages received from commerce sometimes contain insects and usually contain other debris undesirable in a critical room. Such packages should not be opened or stored in critical rooms.

The location, size, and arrangement of storerooms in food-processing plants have also felt the influence of the industrial entomologist. Too frequently storerooms are the neglected rooms and the source of pests and debris in finished products. Fourteen inches of space all about the walls of a storeroom is recommended to facilitate the detection and destruction of pests in the room. Placing stores on skids 8 to 10 inches high aids in insect prevention and sanitation and adds to the attractiveness of the room. It also facilitates moving of materials. Entomology, sanitation, and efficiency are all one in this case.

IN THE STORE ROOM and generally throughout the plant a vacuum cleaner of adequate capacity is a useful tool and one of the finest aids to sanitation.

It is a general rule that where there are no hiding, feeding, and breeding places for insects, sanitation reaches a high plane. The industrial entomologist does not try to kill all the insects that may be found in cracks and crevices in plants. His effort is to have the cracks and crevices closed and to see that conduit switchboxes and similar apparatus do not furnish hiding and breeding places. The sanitation-minded architect and the industrial entomologist avoid false ceilings when- ever possible. Those places furnish sanctuary for many pests and are a source of much airborne debris.

Insects are too mobile to be excluded completely even in the most carefully designed plant. After the architect and the plant engineer have done their best, the industrial entomologist has to resort to insecticides. For use in a food processing plant, insecticides have to be chosen carefully. A guiding factor is the nature of the industry. A few rules apply to all conditions: The desirable insecticide must not have an odor that will be absorbed and retained by the products. It must not corrode equipment. Used with proper caution at recommended concentrations, it must be harmless to personnel. It should be inconspicuous.

Insecticides may be applied as space sprays, residual sprays, or fumigants.

Residual-type sprays combined with proper practices of sanitation and good management and with modern, easy-to-clean equipment have almost completely obviated the need for general space fumigation in food processing. General fumigation is seldom necessary except when insects have gotten out of hand or under unusual circumstances.

Space sprays, the old standbys of industry, do not enjoy the favor they once had. They are usually quite transitory in their insecticidal action and must be constantly repeated where insects find ready entrance. Several hazards accompany the use of space sprays. When they are atomized into a closed space, they must fall mostly on the top of some horizontal surface in the lower part of the room. That may be quite objectionable when food containers are open; their use where food is exposed should be prohibited. Most space sprays contain chemicals that kill insects quickly on contact. Their use must be followed closely with a thorough cleaning of all exposed containers in order to avoid contamination of products by chemicals or dead insects.

Space sprays applied as aerosols are not subject to all of the objections the others have and are often used by the industrial entomologist. Their fine particles usually make aerosols more effective than the others and make possible the use of a much smaller amount. Practically all of the aerosol, except the insecticide, becomes gaseous at atmospheric pressure and there is little danger of damage from precipitated spray material. The same necessity exists for caution in the timing and cleanup after the use of aerosols to remove dead insects as with other space sprays. Insects that fall into containers after the use of an aerosol are just as objectionable as any other dead insects.

Where insecticides are permissible, residual-type sprays have come into use. They are usually more economical in first cost and cost of application and in frequency of use. Residual-type sprays are designed for application only to the places where insects go to rest or roost or hide, of which usually there are relatively few in a processing plant. When the places have been covered with a residue of the insecticide, insects that go to them are killed if the spray material was well selected. The residues often continue to kill for months. They are usually quite effective in preventing insects from breeding. They kill constantly, and insects are not allowed to build up to objectionable numbers. More than any other material in recent years, the residual insecticides have improved sanitation in and about processing plants where food for man or animals or clothing are handled.

Because many insecticides and fumigants are poisonous to humans as well as to insects and because insecticides, like any other material not necessary in the production of food, would be adulterants if permitted to fall into food, only workers trained for the purpose should use insecticides about food-processing plants.

ED. M. SEARLS is entomologist for National Dairy Products Corporation. He spent 11 years in the Bureau of Entomology and Plant Quarantine and was a professor in the department of economic entomology in the University of Wisconsin. He served as entomologist for the 6th Service Command in 1944 and 1945. He is a colonel in the Air Force Reserves and a member of the editorial board of Modern Sanitation. He received his doctor's degree from the University of Wisconsin.