A member of the myrtle family (Myrtaceae), guavas are the pear-shaped fruit of evergreen shrubs or small trees. The common apple guava and the feijoa guava (Feijoa sellowiana), also known as pineapple guava or guavasteen, prefer warm summers and cool winters. The hardy shrub is well-suited for cultivation in U.S. Department of Agriculture hardiness zones 8 through 10. There are literally hundreds of different insects that infest guava trees in various parts of the world. Pest control for guava fruit varies with location and type of insect pest.
Resistant to most disease and insect infestations, feijoa guava trees are subject to fruit flies. The guava fruit fly (Bactrocera correcta) is controlled by the installation of bait traps containing an attractant, usually methyl eugenol, mixed with the pesticide dibrom. To keep traps out of the reach of small children and pets, traps are installed at a height of 6 feet or more. Savvy gardeners often tie small paper bags around each ripening guava to protect the tender fruit from invasive insects.
Mealy bugs are tiny soft-bodied, wingless, white insects that produce a powdery, waxy coating on stems, leaves and fruit. They have piecing mouths that suck the sap from plant tissue. Mealy bugs weaken the guava tree, leading to discolored foliage and leaf drop. Mealy bugs secrete a sticky, sweet liquid known as honeydew. Honeydew attracts aphids and ants. The coconut mealy bug (Pseudococcus nipae) is a major problem to guava growers in tropical locations. The spiked mealybug (Nipaecoccus nipae) is prevalent in Hawaii. Ladybugs are natural predators of aphids and mealy bugs. The syrphid fly and lacewings are other natural predators of aphids.
The encyrtid wasp, Pseudaphycus utilis, is an effective control for mealy bugs and aphids. There are several different species of tiny wasps that parasitize common garden pests, Chneumon wasps, Braconid wasps, and Chalcid wasps parasitize aphids, corn ear worms, white grubs, caterpillars and cut worms. Trichogramma wasps parasitize pest caterpillars including bag worms, army worms, and coddling moths. A natural defense against many garden pests, parasitic wasps are garden friends. They do not sting unless mishandled or provoked. They feed on pollen and nectar and use other insects as food for their larvae. Plant dill or daisies near your guava tree to encourage wasps to inhabit your garden.
The guava weevil (Anthonomus irroratus) bores holes in ripening fruit. The guava fruit worm (Argyresthia eugeniella), the yellow beetle (Theognis gonagia) and the fruit sucking bug (Helopeltis antonii) feast on ripening fruit. To prevent damage, fruit is harvested before ripening.
There are few insecticides approved by the U.S. Environmental Protection Agency for use on guava trees. Chemical pesticides are not used on guava trees when fruit is present. Local county extension agents can provide information on specific insecticides approved in your area.