In Capital Reef National Park, I was a bit surprised to see familiar box elder trees and boxelder bugs. Many Indiana residents are familiar with the orange and black bugs that sometimes invade houses during the winter. The boxelder bugs spend the winter as adults. In nature, they shelter under leaves and at the base of trees. In suburban and urban areas, your house can be a cosy place to spend the winter. They can be a nuisance if found indoors in large numbers, but they cause little economic damage.
The boxelder bug, Boisea trivittata, is a true bug with characteristic sucking mouthparts. They pierce seed pods and stems of plants, inject saliva and suck the juices. The boxelder bugs will feed on a variety of plants during the early spring but move onto trees in the maple family. The boxelder, Acer negundo, is its favorite host plant in the Maple family. Boxelders produce separate male and female trees. The boxelder bug primarily lays its eggs on the female trees. One method of boxelder bug control is to remove female trees.
Boxelder bugs, like most true bugs have glands that secrete odorous substances onto their cuticle. Boxelder bug secretions include several monoterpenes (β-pinene, limonene, myrcene and β-ocimene). The monoterpenes prevent fungal infections by common insect fungal pathogens. The monoterpenes provide some protection from predators who find the monoterpenes distasteful or toxic. Boxelder bugs advertise their distastefulness with their bright orange and black (warning) coloration.
In Capital Reef Park, there were numerous boxelder trees along the Fremont River. I came upon this mating pair of boxelder bugs along a fence rail. Naturally shy, the bugs quickly retreated to a more secluded spot as I tried to take their picture.