Odor Chemistry: Lady Beetle Vs. Marmorated Stink Bug

Chemistry, Nature
It was the ol' one-two. First we were attacked by Asian Lady Bird Beetles, Harmonia axyridis, then the brown marmorated stink bug, Halyomorpha halys. The Lady Bird Beetles were detected first in Louisiana in 1988. Close on its heels, the Stink bugs were detected in Pennsylvania in 1996. Both exude horrible odors when provoked or crushed, though the constituent chemicals are entirely different. Stink Bug Chemistry The stench of the Stink Bug is actually rather simple, as far as stenches go. Two organic compounds, each a "first cousin" of the other, are the culprits: trans-2-octenal and trans-2-decenal (see image). These two compounds are classified as both aldehydes (-CHO) and alkenes (-C=C-). Let's first examine how they are named. Notice both compounds have a straight chain or backbone of carbon atoms…
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