Mango Stem Borer from US Virgin Islands

Subject:  Large Beetle Perched in Papaya Tree
Geographic location of the bug:  St Croix, US Virgin Islands
Date: 04/20/2018
Time: 11:07 AM EDT
Your letter to the bugman:  Good Day,
Hurricanes Irma and Maria randomly seeded our debris-laden yard with a few dozen Papaya volunteers last September (along with tomatoes, peppers, pumpkin and more!). Jan-March we’ve received little to no rains, and so with recent April sprinklings, these parched trees have finally begun setting flower buds. Today while searching for open buds, this intricate beauty greeted me. After admiring his morphology for a timeless hour (or more), I wondered if I could figure out his name. “Large beetle” in Google’s image search did not help, but it did point me to your site ?. Using inches, from “head to toe”, the main body measures 2.5″, with width of “shoulder blades” (widest part) being 3/4″ and width of rounded base being 1/2″. The antenna measures just shy of 3″. I opted not to disturb him, so, I don’t know what the underbelly looks like. What a delightful find. Thank you for providing this ID service and forum ?☀️?
How you want your letter signed:  Lee

Mango Stem Borer

Dear Lee,
This impressive beetle is not native to the Caribbean.  This is an introduced Mango Stem Borer,
Batocera rufomaculata, a species native to Asia.  Its larvae bore in the stems of mango, fig and papaya among other trees.  According to Carnivora:  “A serious pest of edible fig, mango, guava, jackfruit, pomegranate, apple, rubber, and walnut. In India recorded for more than 30 different host plants.  The female cuts the tree bark and lays eggs singly into these cuts, laying a total of up to 200 eggs. Egg is a brownish-white cylinder, 6.2 mm, with narrowly rounded ends. On hatching the larvae start to tunnel into the sapwood of the trunk or branches. Larval development takes about 2 years. As a very large species, the larval tunnel measuring 2 or 3 centimeters in width that is correspondingly large and very damaging to the tree. The larvae tunnel through the sapwood and because of their size, they make large tunnel which interfere with sap flow and affect foliage and fruit production. Attack by Batocera rufomaculata often leads to the death of the tree. Tree death has been recorded in the Virgin Islands, Israel, Mauritius, India and Malaysia. Economic loss can follow when the tree attacked bears fruits or yields another product.”

Mango Stem Borer

Whoa…. so potentially (most likely) this is a female boring eggs into the stem right now. Hmmm… I shall relocate her momentarily, as I believe she chose a host with female flower buds that eventually will fruit. Was kinda hoping the bug was a pollinator vs parasite. Incidentally, this cluster of papaya are growing under what used to be a massive Mango canopy, felled by recent hurricanes. The past 4-5 years, it rarely produced mangos, and if so, on a only few branches (15% at best). Whereas 5-6 years ago, it was fruiting heavily. Mr Bugman, I sincerely appreciate your ID expertise. Simultaneously, you solved our long curiosity as to why mangos systematically stopped appearing on our once-massive tree  Thank you, Lee

Hi again Lee,
In our opinion, the pictured tree upon which you found this Mango Stem Borer is too young to be able to support a growing larva.  There is some evidence that adult beetles feed on leaves, based on this image we located on Dreamstime.

That’s a cool foraging pic. Thank you for the addition info and links. What an enjoyable, interactive, backyard entomology trip

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