• Abstract and Figures
• Public Full-text

Dustywings on Citrus these natural enemies of mites and scales may be helped by miticides but are killed by insecticides C. A. Fleschner Dustywings-natural enemies of citrus which are free of mites if honeydew- mites and scales-need their prey as well secreting insects are present. Thus, it is as honeydew-secreting insects to survive. possible to treat citrus trees with mite In the insectary adult dustywings live toxicants which do not kill insects and for weeks on a diet of certain sugars still allow a dustywing population to exist alone. These sugars may be in the form in the grove. of honey, plant nectar or honeydew, the Field experiments in co-operation with latter being secreted by such insects as the Division of Entomology have shown scales, mealybugs, or aphids. Dustywings that when noninsecticidal sprays and restricted to such a diet, however, rarely dust materials, such as Ovotran and Ara- produce eggs. But when mites or scales mite, are used for mite control, existing are added to this honey diet, egg produc- dustywing populations are sustained by tion soon begins. Adult dustywings fed The dustywing, Parasamidalis flaviceps, adult. low populations of the various species of honey and mites, or honey and scale in- Actual sire 3.7 millimeters. insects remaining alive in the grove. The sects, live and produce eggs for a period predaceous activity of the dustywings of several months in the insectary. When their prey. The adults consume whole in- thus maintained serves to prolong the fed on mites or scale alone, with no honey dividuals of the prey, legs and all. Adults period of effective mite control brought available, the adults will die within a are probably more effective as predators about by the toxicant. few days. since an adult consumes more prey daily The dustywing is a delicate, whitish, than a larva and the greater portion of Best Control humpbacked insect, little more than %’’ the life span of an individual is spent in The very best examples of biological long. It has a dusty appearance, its wings the adult stage. and body being covered with a powdery, control of the citrus red mite have been wax secretion. Dustywings belong to. the found in groves which receive no insecti- Coniopterygidae, a family related to the Prey on Scale Insects cidal or acaricidal treatment whatsoever. brown and green lacewings. They may be Dustywings on citrus have been gen- These groves have low populations of found on citrus trees throughout the year erally thought of only as mite predators; both citrus mites and scale insects-well wherever citrus is grown in California. however, in the insectary the adults prey below the threshold of economic impor- All their life stages inhabit the citrus more readily on the crawlers and young tance-and relatively high populations of trees. About dusk the adults may be seen stages of armored and unarmored scale dustywings. actively flying about in the groves. insects than on mites. Attempts to raise Adults of the dustywings are, in gen- dustywing larvae to maturity on a diet eral, very sensitive to insecticides. For example, DDT field residues over eight Active in California of citrus red mites alone have proved un- successful. Larvae fed a pure diet of months old killed 100%.of adult dusty- At least four different genera-Para- young stages of scale insects readily de- wings exposed to them for a period of semidalis, Conwentzia, Coniopteryx, and velop to maturity. Dustywing larvae also 12 hours. This is doubtless one of the fac- Malacomyza-are active predators in develop readily on a diet consisting only tors contributing to the increase of citrus California citrus groves. Jndividuals of of citrus rust mites. mite populations following the use of the different genera are fairly similar in In the insectary dustywings were DDT. their general reactions and their food reared by using red scale crawlers pro- C. A. Fleschner is Assistant Entoniologist, habits. duced on potato tubers. The diet of the University of Calijornia College oj Agriculture, Larval and adult stages of dustywings adults was supplemented with honey. Riverside. are predaceous. The larvae, with piercing The above progress report is based on Re- mouth parts, suck the body juices from Field Experiments search Project No. 1495. To maintain a population of dusty- wings in the field, some source of nectar or honeydew as well as mites or scales must be available. For this reason dusty- wings are apt to do poorly in groves treated with materials which destroy the honeydew-secreting insects. On the other hand, dustywings may be active in groves Left, Pararamidolis flaviceps egs, actual sire .7 millimeter. Right, Parasemidalis flaviceps Bank larva, actual sire 3.5 miilimeters. Photogrophr hp Airc/o McD. lohnron 4 CALIFORNIA AGRICULTURE, JULY, 1952 .

Load more

  1

Copy Link