Eucalyptus Tortoise Beetle

EUCALYPTUS TORTOISE BEETLE Integrated Pest Management for Home Gardeners and Landscape Professionals The eucalyptus tortoise beetle 1⁄4 to 3⁄8 inch long and superficially re- (Trachymela sloanei), an Australian leaf semble a large lady beetle. Female beetle (family Chrysomelidae), was beetles lay 5 to 40 or more eggs in an found in 1998 in Riverside County. It irregular group under loose eucalyptus now occurs throughout southern Cali- bark. Eggs are pinkish brown when fornia, in the Central Valley, and in the laid and become dark purplish before San Francisco Bay Area. Because adults hatching. Larvae resemble caterpillars are strong fliers, it is expected to (larvae of butterflies and moths) but spread to most locations where euca- can be distinguished by their append- lyptus trees grow. ages. Larvae of tortoise beetles (Fig. 2) and other leaf beetles have three pairs DAMAGE of true legs on their thorax and do not Adult beetles and larvae chew semicir- have any prolegs (fleshy, round, cular or irregular notches along edges leglike protuberances) on their abdo- of eucalyptus leaves (Fig. 1). The men. Caterpillars and sawfly larvae beetles can remove most of a leaf’s have three pairs of true legs on their surface, leaving only the midvein. thorax plus several pairs of prolegs on Adult beetles will also snip off young their abdomen. terminals as new foliage is produced by trees. Heavily infested trees lose Tortoise beetle larvae are reddish most of their leaves, which increases brown to green and have a black head tree stress. Although the eucalyptus and black prothoracic shield (top and Figure 1. Eucalyptus tortoise beetle tortoise beetle alone is not known to sides of the first segment behind the adults and larvae chew irregular notches kill trees, this species adds to the more head). Larvae develop through four along leaf edges. than one dozen new eucalyptus pests immature stages before pupating be- introduced into California during the neath loose bark adhering to trees or last two decades. One or more of these dropping from the canopy to pupate in scraping leaf surfaces, leaving discol- other pests (such as longhorned borers the soil or litter around the base of host ored trails of tissue and causing elon- or redgum lerp psyllid) or several pests trees. At warm temperatures, develop- gated holes in the center of leaves. or maladies in combination can kill ment time from egg to adult may be as Older snout beetle larvae feed along trees, especially if growing conditions short as 5 weeks. There are several the margins of leaves and consume or tree care practices are not optimal. generations each year from late winter large irregular patches of leaf tissue. through fall. This snout beetle feeding pattern is The Eucalyptus species preferences of distinctly different from the leaf-edge eucalyptus tortoise beetle have not Eucalyptus tortoise beetle can readily been well documented, but certain tree be distinguished from the only other species are apparently preferred or eucalyptus tree defoliator reported in avoided by this beetle and other major California, the eucalyptus snout beetle eucalyptus pests as summarized and or gumtree weevil (Gonipterus compared in Table 1. scutellatus). Eucalyptus snout beetle adults are reddish brown weevils with (actual IDENTIFICATION AND an elongate head, as opposed to the size) LIFE CYCLE hemispherical shape of the tortoise Eucalyptus tortoise beetle adults are beetle. The legless snout beetle larvae hemispherical and brown with darker are yellowish green with a slimy coat- Figure 2. Eucalyptus tortoise beetle mottled spots (Fig. 2). Adults are about ing. Young snout beetle larvae feed by adult (left) and larva. PEST NOTES Publication 74104 University of California Agriculture and Natural Resources January 2003 January 2003 Eucalyptus Tortoise Beetle psyllid (Ctenarytaina eucalypti) and Table 1. Approximate Relative Susceptibility of Eucalyptus Species to Several eucalyptus snout beetle. Learn how Introduced Pests in California. management efforts may affect these Common name Eucalyptus Longhorned Redgum Tortoise introduced pests before taking any (gum) species borers1 lerp psyllid beetle actions against eucalyptus tortoise Australian beech polyanthemos —LLbeetles. Provide trees with good cul- blue globulus MI–L2 M tural care and avoid actions that are desert rudis —MI harmful to natural enemies being intro- dollar leaf cinerea —L—duced to control this pest and other flooded grandis IIMeucalyptus pests. forest red tereticornis —M— gray ironbark paniculata —L— hybrid trabutii L——Cultural Control Karri diversicolor MI—Minimize tree stress by providing eu- lemon citriodora LI3 L calyptus trees with proper cultural care long flowered macandra —I —and protecting them from injury. De- manna viminalis MIMpending on the situation, consider mountain dalrympleana L——providing trees with supplemental narrow leaved spathulata —L—water during periods of prolonged Nichol’s willow leaved nicholii —I — red flowering ficifolia —LLdrought, such as during summer and red ironbark sideroxylon LI–LLfall in much of California. Some euca- river red camaldulensis LMMlyptus species are drought-tolerant, but round leaved/red flowered platypus/nutans MI–L—others require more moisture. If irri- shining nitens MM–I—gating, avoid frequent, shallow water- silver crenulata ——Ling that is often used for lawns. A silver dollar pulverulenta —L2 — general recommendation is to irrigate spotted maculata ——3 L sugar cladocalyx LI–L—eucalyptus trees infrequently (possibly swamp mahogany robusta LL—once a month during drought periods) Sydney blue saligna ML—but with sufficient amounts so that the white ironbark leucoxylon —I —water penetrates deeply into the soil —= information not available (perhaps about 1 foot or more below M= more or most susceptible the surface). This can be achieved by I= intermediate susceptibility applying water slowly through drip L= less or least susceptible or reportedly not attacked emitters that run continuously for sev- Redgum lerp psyllid = Glycaspis brimblecombei Tortoise beetle = Trachymela sloanei eral days. In areas without an estab- lished irrigation system, a water tank 1 Longhorned borers = reported susceptibility to Phoracantha semipunctata, which is believed to be similar to the susceptibility to P. recurva. truck can be used to temporarily flood 2 Susceptible to bluegum psyllid (Ctenarytaina eucalypti), but this psyllid is generally soil. However, avoid prolonged water- under good biological control. logging, especially around the root 3 Susceptible to spotted gum psyllid (Eucalyptolyma maideni) and lemongum lerp psyllid (Cryptoneossa triangula). crown, because eucalyptus trees are susceptible to pathogens such as Adapted partly from: Brennan et al. 2001, Hanks et al. 1995. Armillaria and Phytophthora root rot, which are favored by wet soils. The specific amount and frequency of wa- notching caused by tortoise beetles. feeding adults or larvae are observed ter needed varies greatly depending on Because eucalyptus snout beetle is on foliage, inspect beneath loose bark the site and tree species. under good biological control from an where adults, egg masses, larvae, and egg parasite (Anaphes nitens) intro- possibly pupae can be observed and Biological Control duced by University of California sci- collected for identification. Eucalyptus tortoise beetle is not nor- entists, it is now uncommon and no mally a pest in its native home of Aus- longer a pest. MANAGEMENT tralia; presumably natural enemies Eucalyptus trees are attacked by sev- there keep beetle populations low. The cause of feeding damage and eral other insects, including eucalyptus University of California scientists are notched leaves of eucalyptus may not longhorned borers, redgum lerp psyl- introducing a tiny egg parasite be obvious because most tortoise beetle lid, and other psyllids. For more infor- (Enoggera reticulata, family Pteroma- larvae and adults hide under loose mation on these pests, see the Pest lidae), originally from Australia, into bark during the day and feed primarily Notes listed in References. Some euca- California in an effort to control the at night. Also, they may be concen- lyptus insects are now under good beetle. This parasite searches under trated high in the tree. If no leaf- biological control, including bluegum eucalyptus bark and in cracks and fis- ◆ 2 ◆ January 2003 Eucalyptus Tortoise Beetle sures, laying its eggs in tortoise beetle ucts (Bayer Advanced Garden Tree & REFERENCES eggs. The parasite larva feeds inside the Shrub Insect Control) are available to Brennan, E. B., G. F. Hrusa, S. A. egg, turning it reddish orange, often home gardeners. Certain formulations Weinbaum, and W. Levison. 2001. with black spots. An adult parasite then of insecticides with systemic or trans- Resistance of Eucalyptus species to emerges to seek and attack more beetle laminar activity (able to penetrate leaf Glycaspis brimblecombei (Homoptera: eggs. In addition to beetle eggs killed tissue) can be sprayed onto foliage, but Psyllidae) in the San Francisco Bay by parasite larvae, adult female para- soil applications and tree injections (if Area. Pan-Pacific Entomologist 77: 249– sites feed on the eggs, which kills many labeled for these methods of applica- 253. additional beetle eggs. tion) minimize environmental contami- nation, are less disruptive of natural Dahlsten, D. L., S. H. Dreistadt, R. W. It is not currently known whether bio- enemies of other insect pests, and are Garrison, and R. Gill. Dec. 2002. Pest

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