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Let bugs eat bugs 3

Written by horticulture  |  11. March 2004

The next groups of beneficial insects to cover are aphid and white fly predators. Aphidius matricariae, the aphid parasitoid, is a sting less mini wasp that lays its eggs inside the host aphid. When the egg hatches, the larvae begin to eat the aphid from within, finally emerging as an adult. Parasitized aphid "mummies" (aphids will appear thin and paper like) will be readily noticeable. These mini wasps will establish themselves to a certain degree, but multiple releases may be needed. A. matricariae should only be used when aphid populations are low. Release 1-8 per yard, 2-4 times a month starting in early spring. Another aphid parasitoid is the Aphelinus abdominalis. This is another mini wasp who lay their eggs inside aphids. The main difference between A. abdominalis and A. matricariae is that the A. abdominalis mummies turn black instead of tan. Release rates and timing are the same as A. matricariae. Next on the list is the aphid midge, Aphidoletes aphidimyza. These tiny mosquito like flies are predatory in both the larval and adult stages. The more aphids you have- the more they like it, the faster they will reproduce and the longer they will stay around. These midges are nomadic, so they will travel to where the aphid populations are the highest. Release 2-9 per yard bi-weekly starting in the spring. Green lacewing (Chyrsoperla rufilabris) will not only control caterpillar eggs, as stated in the December '03 column, but they will also do a great job on aphids. The larvae should be dropped into or near a concentration of aphids for best results. Release 2-9 per yard bi-weekly starting in mid spring or when aphids are noticed. By far the most popular aphid predator are Hippodamia convergens- the convergent lady beetle (or ladybugs to the layperson). These little ladies are dangerous to aphids in both their larval and adult forms. The adult lady beetle is easily recognized by their black spotted orange/ red wing covers. The larval form is not so easily recognized at first, but once you see them you will never forget them. The larvae look like tiny black alligators with orange markings down their sides. Releases should be done in small batches to ensure good control starting in the spring. Release 4-14 per yard every 2-4 days or weekly if aphid populations are low. Be aware that many of the lady beetles will fly away to other areas, but enough should hang around for good control. White fly has become more of a problem over the past few years, probably due to the fact that many of the predators have been wiped out by the pesticides that we have been using. So here are some predators that have been found to work well. Dephastus catalinae, the white fly destroyer, are very efficient white fly predators to a point. These tiny beetles will eat several hundred white flies a day, which will lower damaging white fly populations dramatically, however, the adults will not always finish off all the white flies, but will save some for their larvae. The females lay 3-4 eggs a day and live for about a month. Both the larval stage and the adult stage are predatory. Release 100 beetles per 1500 sq ft when white fly populations are high (usually in early to mid summer). Encarsia Formosa, the green house white fly parasitoid, is a mini wasp who lay their eggs in the white fly eggs, after about 20 days, the adult wasp emerges from the egg and begin the process all over again. These parasitoids are shipped on cards that you hang in the effected plants. Hang 1-2 cards per plant (each small card contains 100 parasitized eggs), starting at first signs of white fly activity. These white fly controls should be used in conjunction with green lace wing (Chyrsoperla rufilabris), which will also prey on the white flies very effectively. If you have any questions or would like clarification on anything, please let me know. You can reach me at 631-691-2381 (office) 631-404-6802 (cell) or aplantdoctor@hotmail.com.

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