LIBRARY STATE tLANT BOARD E-465 February 1939 United States Department of Agriculture Bureau of Entomology and Plant Quarantine SOME RESULTS OF RECENT WORK WITH DRIED-FRUIT INSECTS 1/ By Perez Simmons, Dwight F. Barnes, Charles K. Fisher, and George H. Kaloostian, Division of Fruit Insect Investigations It is a pleasure to bring to the annual meeting of the Dried Fruit Association of California a report of some of the results of work done at the Fresno laboratory of the Bureau of Entomology and Plant Quarantine, United States Department of Agriculture, during the past year. Protection of Peaches In 1936 we completed our experimental work with shade-cloth protection of peaches, apricots, and nectarines drying on stacked trays. During the 1937 and 1938 drying seasons tests of other methods of handling peaches were tried. It was found that several schedules for handling peaches can be used to reduce infestation by the raisin moth (Ephestia figulilella Greg. ) . These schedules postpone protective measures until the drying of peaches on stacked trays has been completed. Various combinations of fumi- gation and shade-cloth protection were tried first in 1937 and were repeated with comparable results in 1938. We believe the best of these schedules is the one that calls for fumigation of the fruit as soon as it is boxed from stacked trays and subsequent protection with shade cloth during temporary storage in boxes on the ranch. In the work done in 1938 the peaches averaged 72 percent infested when they were boxed, but immediate fumigation followed by shade-cloth protection during the storage period of 15 days on the ra'' ch resulted in the avoidance of all visible infestation. Unprotected peaches of the same crop (of the Elberta and Muir varieties) were 99 percent infested after 15 days in boxes. The infestations present in samples of peaches collected on the ranch could not be determined accurately by immediate examination because of the small size of the eggs and larvae. All samples were held for 6 weeks to allow time for the insects to reach easily visible size. The method of fumigating at boxing and subsequent protection with shade cloth during storage in boxes on the farm has the advantage of re- quiring less shade cloth than is needed when peaches are protected with cloth during stack drying. On the other hand, there ib some expense for 1/ This paper was read at the 31st Annual Meeting of the Dried Fruit Association of California, San Francisco, January 12, 1939. -2- fumigation, and the irethod is subject to the objection that the raisin moth ha"" access to the fruit during stack drying and establishes on it con- siderable infestation. When the fruit is boxed, after having been in the stack for from 6 to 10 days, the infestation consists of eggs and very small larvae. The eggs hatch in 3 or 4 days. It follows that, at the time of boxing, after 10 days in the stacks, the larvae are not more than a week old, assuming that the weather has been hot and that no additional infestation became established on the peaches during spread drying. Growth of the larvae on peaches a.ppears to be slow, and they are very small when killed by fumi- gation at boxing. Although, as shown by unprotected samples, infestation was present on 72 percent of the halves when fumigation was done at boxing, this minute dead infestation was not found when samples of fumigated and protected fruit were examined 6 weeks later. Insects in Raisin Storages A series of samplings of stored raisins, taken from February to Sep- tember 1937, gave information on the kinds of insects present and on their relative abundance. The saw-toothed grain beetle (Oryzaephilus surinamensis (L.)) was by far the most abundant species. A discussion of this survey was presented at the annual meeting of your Association in 1938. During 6-|- months in 1938, from the middle of April to the end of October, we nr.ade a survey of a different kind, intended to give information about the flight of insects in a raisin storage yard. For this purpose a rotary net was operated, day and night, at a speed of about 21 miles per hour or 500 miles per day. The net, which was 18 inches in diameter, revolved horizontally at an elevation of 3 feet. The insects were collected daily, or at more frequent intervals, on 191 days. Many of the insects were of no interest and were discarded. Five species of moths and 10 species or groups of beetles were recorded, and the total number of individuals was 887,000. The raisin moth (Ephestia figuli- lella Greg.) was the most abundant of the moths, with the Indian-meal moth ( Plodia interpunctella (Hbn.)) in second place. Of the beetles, the dried- fruit beetle (Carpophilus hemipterus (L.)) was taken in greatest numbers, closely followed by the so-called skin beetles, of the family Dermestidae, which appear to subsist in raisins largely on the bodies of dead insects. In addition to a record of the changing abundance of raisin-infesting insects from month to month, the survey gave us for the first time a detailed picture of their daily flight habits. These details were obtained by re- cording the abundance of the different species in catches taken from the net every 15 minutes, both all day and all night, on several occasions in the summer and fall. During the day the only species which flew plenti- fully were the dried-fruit beetle and the skin beetles. The other beetles and all of the moths became active, rather abruptly, shortly after sunset and continued to fly in considerable numbers for a few hours, after which the population in the air declined. Flight of the moths ceased about sunrise, but a few night-flying beetles were on the wing during daylight. -3- The fact that many insects are most active early in the evening is evident to all motorists whose windshields become covered with the crushed bodies of numberless individuals at that time of day. It is of im- portance for the dried-fruit industry to know that this behavior is definite- ly characteristic of most of the beetles and all the moths which are found around the packing house. Fruit left exposed, or even packed, is likely to be visited by some of these nocturnal animals, the females of which prowl around in search of materials on or near which to lay their eggs. The primary objective of the survey was to determine whether or not the saw-toothed grain beetle can fly. If it can fly, attempts to keep raisins that are received in clean condition from becoming infested by this most abundant storage insect will be difficult. If it cannot fly, the use of some kind of simple barrier around stacks of raisins should give adequate protection. Although no observations of the flight of the saw-toothed grain beetle had been recorded, it was evident that the use of the rotary net would decide the question definitely. Our records show that very few of them were taken in the net. The total for 6^ months was only 180, a negligible number compared with the resident population. It should be possible, therefore, to exclude the saw-toothed grain beetle from clean raisins by installing barriers, such as metal troughs filled with oil, over which they cannot crawl. 90Z9 9C360 3931. € llliililiiliiliiil VaiyOld dO AilSHBAINn 1