About a new­pest: the bagrada bug


The bagrada bug ( Bagrada hi­laris), an African na­tive, was first found in Cal­i­for­nia in 2008. By 2010, it had spread to south­ern New Mex­ico and was found in Santa Fe County in 2012. Adults and nymphs pierce leaves, stems, flow­ers, and seeds with their nee­dle-like mouth­parts, in­ject di­ges­tive en­zymes, and suck plant juices. Star­burst-shaped, brown le­sions form on leaves and stems. Other dam­age in­cludes “scorched” leaves, stunted growth, and forked or mul­ti­ple heads on cau­li­flower, broc­coli, and cab­bage. Bagrada bugs may kill seedlings.

Bagrada bugs pre­fer to feed on mem­bers of the Bras­si­caceae fam­ily, which also in­cludes kale, mus­tard, and arugula; and or­na­men­tal plants such as sweet alyssum, stock, and can­dytuft. How­ever, they may eat many dif­fer­ent crops, among them corn, pota­toes, tomatoes, as­para­gus, melons, car­rots, pep­pers, roses, and cot­ton. The bugs feed on both cru­cif­er­ous plants (wild mus­tards, shep­herd’s purse, Lon­don rocket) and non-cru­cif­er­ous weeds (lambs quar­ters, pur­ple nutsedge, field bindweed). The adults are shield -shaped and 3/16- to 1/4-inch long and are black with orange mark­ings. The first in­star nymph is bright orange and the sec­ond through fifth nymphs are red with dark mark­ings.

Bagrada bugs over­win­ter as adults in leaf lit­ter or top­soil. In the spring, fe­males lay their eggs (singly or in small batches) on the soil sur­face or on the leaves of host plants. Each fe­male lays about 100 eggs in her life. The eggs hatch in four to nine days. Lar­vae progress through five stages. The egg-to-egg cy­cle de­pends on the tem­per­a­ture, gen­er­ally tak­ing 38 to 65 days. In New Mex­ico, two or three gen­er­a­tions per year are pos­si­ble. They be­come lo­cally abun­dant in mid-July and may reach high den­si­ties with hun­dreds of bugs feed­ing on a sin­gle plant.

Con­trol of the bagrada bugs is dif­fi­cult. They are not eas­ily seen un­til the in­fes­ta­tion is out of con­trol. Feed­ing dam­age is easier to spot ear­lier in the sum­mer than the in­sects them­selves; they are more ac­tive (and more eas­ily spot­ted) when the tem­per­a­ture is above 75 de­grees.

In a home gar­den, the bugs can be re­moved by hand (wear gloves — they stink) and drowned in soapy wa­ter. Large num­bers of bugs can be shaken onto a sheet and vac­u­umed. The trapped bugs should then be bagged or killed since they can sur­vive vac­u­um­ing. Pyra­mid traps baited with crushed sweet alyssum can de­stroy bugs, par­tic­u­larly when num­bers are high. These traps can be made from soda bot­tles or adapted from com­mer­cially avail­able stink bug traps. (Chem­i­cal lures that at­tract other stink bugs will not work.)

Cur­rently there are no ef­fec­tive bi­o­log­i­cal con­trols in the USA. Birds find their taste to be un­pleas­ant. The adult bugs usu­ally es­cape pes­ti­cides by fly­ing away only to re­turn later. Un­til there are ap­proved pes­ti­cides, home veg­etable grow­ers need to use man­ual meth­ods or bag the plant (in­clud­ing the stem) to ex­clude the bugs.

Terry McGuire was a pro­fes­sor of ge­net­ics at Rut­gers Univer­sity for 36 years. He was also a se­nior fel­low of theNa­tional Cen­ter for Science and Civic En­gage­ment, help­ing ed­u­ca­tors con­nect science to civic is­sues. He moved to Santa Fe in 2014. He is a Master Gar­dener and a Master Com­poster.


a non-hi­lar­i­ous in­sect

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