The dried fruit beetle is a small, flat oval-shaped beetle about 1/8 inch (4 mm) in length that is dark brown to black in colour. Like most sap beetles of the family Nitidulidae, the elytra (wing covers) of this beetle are fairly short, leaving a portion of the abdomen exposed. The wing covers of the dried fruit beetle extend only a little more than half way down the abdomen and contain yellowish markings on them.
This beetle attacks both fresh, ripped fruit and dried fruit prior to storage and packaging, especially figs and dates and, to a lesser extent, raisins. Dried fruit beetles are found worldwide, especially in regions where fruits are grown, processed and stored. It takes only a few dried fruit beetle larvae to render a quantity of figs or dates unpalatable due to the mass of feces and cast skins left behind. This beetle is of concern to packers, food retailers and the consumer.
Dried fruit beetles are generally pests in facilities where figs, dates, raisins and other fruits are dried and processed and do not usually end up in packaged and do not usually end up in packaged dried fruit products at the consumer level. If any of these beetles are found in a building, the obvious areas to inspect are where fruit products are stored. If this is the case, the building needs to be examined for possible sites where beetles can enter – cracks around doors, damaged window screens, doors left open, etc.
The female dried fruit beetle lays more than 1000 tiny, white eggs on ripening fruit on trees or fruit on trays drying in the open, so infestations often begin prior to the fruit being processed or stored in packing sheds. Refuse dumps are also sources of dried fruit beetles. Infestations occur before the fruit is completely dry, and usually occur only on cracked or fermenting fruit – sound fruit is rarely attacked.
The larvae are white to amber in color and grow to about 7 mm in length. Development to the pupal stage takes up to four weeks but as little as two under optimum conditions. During this time, the very active larvae undergo several molts leaving behind a cast skin after each molt. The pupal stage lasts about two weeks. The life cycle can be completed in a minimum of 15 days during the summer but may take months during winter.
Inspect for spillage of fruit product in corners, behind pallets and in storage racks. A small amount of fruit product can support a number of beetles and serve as a reinfestation source for newly introduced fruit products. Pieces of ripened melon placed in jars may serve as monitoring traps to help determine areas of infestation.
New infestation are commonly carried in from the field and prompt identification of beetles and prompt attention will generate avert more serious infestations. Control efforts directed at the orchards themselves, such as regular removal of fallen fruit, will reduce the numbers of beetles in the orchards.
When fruits are brought into the building, they should be dry to attract fewer beetles. Dumpsters outside buildings where unwanted fruit debris is discarded require regular pick-up by the trash company and also regular, thorough cleanings to attract as few beetles as possible. The dumpster should be located as far from the building as possible, and doors in the area should be kept closed.
General and/ or spot applications of an appropriately labeled residual insecticide are sometimes used in fruit processing facilities to control dried fruit beetles. These applications are made to surfaces where these beetles might land or crawl.