Introduction - Synonymy - Distribution - Description - Biology - Damage - Management - Ecological Interactions - Selected References
The crapemyrtle aphid, Sarucallis kahawaluokalani (Kirkaldy), is the most important insect pest of crape myrtle Lagerstroemia spp. in the United States. Although native to southeast Asia, crapemyrtle aphid was described by Kirkaldy from specimens collected in Hawaii. In the U.S., crapemyrtle aphids are monophagous; feeding exclusively on crape myrtle and do not attack or damage other plant species. Heavy infestations may cause cosmetic damage that detracts from the visual aesthetics of crape myrtle, but feeding has not been shown to have long term effects on plant health or vigor.
Nymphal stages of the crapemyrtle aphid are pale to bright yellow with black spike or hair like projections on their abdomen. Adults are also yellow in color but differ from nymphs in having black spots and two large black tubercles on the dorsal surface of the abdomen. Unlike other aphid species that produce winged forms as a result of environmental or reproductive stimuli, all adult crapemyrtle aphids bear wings that are held roof like over the body and mottled with black markings.
When photoperiod and temperature decrease in the autumn, virginoparae give birth to a generation of aphids that produce both male and female aphids (sexuparae). Female offspring of sexuparae (oviparae) mate with males and produce eggs. Oviparae produce four to six eggs and place the eggs in crevices located on the bark of crape myrtle stems. Overwintering eggs will hatch the following spring in response to temperature and photoperiod stimuli.
Crapemyrtle aphids have four nymphal stages (instars) before developing into adults. Development time is dependent on ambient temperature, and under optimal conditions, crapemyrtle aphids can develop from first instar nymph to adult in five days. Adults give live birth to first instar nymphs that began developing within their mother when she was a nymph. Therefore, each virginoparae adult is capable of producing offspring upon emergence and can produce six or more offspring within 24 hours of becoming an adult. Adults may live as long as 14 days and produce over 150 offspring in their lifetime. Under optimal conditions, aphid populations grow at astonishing rates due to the high levels of fecundity and low development times. Aphid populations are commonly ignored or escape detection until they have reached damaging levels.
Amino acids and other essential nutrients are separated with a special filter chamber located in the gut, and excess sugar and water are excreted from the body as small sugary droplets called honeydew. Crapemyrtle aphids eject honeydew away from their feeding location preventing them from becoming entangled within the sticky secretion. Honeydew accumulates on objects below aphid populations and is commonly seen as a shiny coating on the tops of leaves and stems. Molds and other microorganisms can grow on these surfaces utilizing the rich sugary honeydew as a food source.
Black sooty molds are fungi that grow on honeydew produced by aphids or other phloem feeding insects. Capnodium is a genus of fungus that has a species associated exclusively with crapemyrtle aphid honeydew. This fungus species is not yet described and therefore is known only as Capnodium sp. Black sooty mold can turn the entire plant and unsightly black color detracting from the visual aesthetics of crape myrtle. When aphid infestations are severe, thick carpets of black sooty mold interfere with photosynthesis and may cause early leaf drop or complete defoliation of affected plants. However, defoliation is unlikely to affect long term plant health or vigor and plants typically rebound and bloom beautifully in the following years.
multicolored Asian lady beetle
Alternative control tactics for controlling crapemyrtle aphids are insecticidal soaps or systemic insecticides. Insecticidal soaps can be used to control heavy aphid infestations, but should be used only when aphid populations have escaped natural control and as a last resort. If applied with the proper timing and dosage, systemic insecticides may prevent the formation of aphid populations. Insect Management Guide for landscape plants
Predaceous Hymenoptera such as paper wasps (Vespidae), Sphecid wasps (Sphecidae), ants (Formicidae), and parasitoids use honeydew as an adult energy resource. Studies indicate that adult Hymenoptera have increased longevity and foraging efficiency when provided with a source of sugar like honeydew. Contrary to popular belief, wasps can be extremely beneficial in the landscape for controlling insect pests. Paper and Sphecid wasps prey on caterpillars, spiders, and other arthropod pests that are commonly found in backyards and gardens. Ecological interactions are important considerations before deciding on a management practice. Insecticidal sprays and soaps do not generally discriminate between predator and prey, and thus, should only be used when absolutely necessary.
Author: John Herbert, and Russ F. Mizell III, University of Florida
Photographs: John Herbert, University of Florida
Project Coordinator: Thomas R. Fasulo, University of Florida
Publication Number: EENY-365
Publication Date: February 2006
Copyright 2006 University of Florida
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Department of Entomology and Nematology
Division of Plant Industry
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nymphs and adult
close up of life stages
crapemyrtle aphid infestation
black sooty mold