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However, an alert has been announced for another potentially damaging imported beetle, the citrus longhorned beetle. The state Department of Agriculture found this relative of the Asian longhorned beetle after being notified by a nursery owner in Tukwila who observed the beetle on a shipment of maples that were in their 8th month of a quarantine period (being watched before being released for sale.) Because many beetles resemble the Asian longhorned beetle, the insects caught in Tukwila were sent to the Smithsonian Institution in Washington DC for positive identification.
The new pest was identified as citrus longhorned beetle on August 10, 2001. The affected trees have all been destroyed but inspectors also continue to check the neighborhood for adults and eggs of the pest. Another specimen was found in a nursery in Lacey (Thurston County, on August 16.) The citrus longhorned beetle closely resembles the Asian longhorned beetle and is potentially as destructive, attacking forest trees including maple, poplar, and alder. They kill trees by boring large holes through the heartwood of the tree, causing serious damage to live trees.
How can you identify this beetle? This may be difficult because there are many look-alikes but the general characteristics of the insect are distinctive. The beetle is crisply black and white, and large, about 1-1.5 inches long with distinctive long curved antennae stretching from the head and extending wider than the body. The colors (black and white) and size make it easy to spot beetles of this type, though an untrained person might find positive identification difficult. Because of the seriousness of the potential problem, the Washington State department of Agriculture says:
If you see one of these beetles, or are uncertain of the identification of a black and white beetle, scoop it into a jar or other container and then call (800) 443-6684. · Photos are on the internet at: http://whatcom.wsu.edu/ag/homehort/pest/Longhorn%20Beetles.htm ·
A local look-alike is the banded alder borer, a local forest insect that's relatively harmless because it attacks and recycles dead or dying trees. It's also black and white, with long antennae, but has a different pattern of markings across the back: the back shows alternate bands of black and white, in bands extending all the way across the insect's body. Since the alert began in early August, over 700 reports of beetle sightings have been called into the state, most proving to be banded alder borer. When you look at the photo of the destructive citrus longhorned beetle, you'll notice that the black and white pattern on the back isn't continuous or banded, but is in random spots. (One Asian term for beetles like the Asian longhorned beetle and citrus longhorned beetle is "starry sky beetles" because the pattern on the back looks like white lights against a dark sky.)
The new pest arrival, the citrus longhorned beetle, is being aggressively hunted and the intention of the Washington State Department is to eradicate it completely before it becomes established here. The difficulty faced by state entomologists is that evidence indicates the possibility of citrus longhorned beetles from the Tukwila site as not having been completely eliminated. 369 bonsai maple trees were destroyed there, and dissected to look for the characteristic exit tunnels. Eight tunnels were found but only 3 beetles were captured. The "worst case scenario" according to Brad White of the WSDA, is that five are on the loose. At the Lacey site, only one was found, and one other exit hole, so the probability is that the one remaining beetle couldn't reproduce.
Each female can make up to 200 eggs after mating, and each egg is separately deposited in tree bark, so it's possible for one female to contaminate many different sites. The hole where the eggs are laid is extremely difficult to see. After the beetle larva hatches, it chews into the tree, forming a tunnel. This tunnel is then used as a place for beetle pupation (the process of growing from larva to adult) and the adult beetles then emerge. From egg laying to pupation and adult emergence can take 12 to 18 months, so it's a long monitoring period required. Linda Waring of the WSDA noted "we will have to take a long-term approach to monitoring for the beetles."
Gardeners and landscapers can help by checking the web sites and learning the difference in appearance between the local banded alder borer and the harmful imported citrus longhorned beetle. If you have any doubt, capture the insect and call the Department of Agriculture.
Hortsense: Managing plant problems with Integrated Pest Management
