If you’ve lived in Arizona long enough, then chances are you’ve seen a Palo Verde beetle or two – or more, since they come out by the hundreds of thousands between July and August. The Palo Verde root borer beetle, so-called because as grubs they especially enjoy munching on distressed roots of the Palo Verde tree, look like burlier cousins of the cockroach and can grow to around 3 to 3.5 inches long, making it one of the largest beetles in North America.
They range from dark brown to black in color, have wings that are almost as long as their bodies, and long antennae. They also have spikes on their thorax or middle section, and these may be sharp enough to cut through skin if you pick them up.
Though they prefer Mexican Palo Verde trees, they’re also found on olive and rose trees. While similar species are found throughout the northwest, these beetles in particular are most common in the Phoenix and Tucson areas.
Every summer monsoon season, like clockwork, these beetles take to the air to find love. They can spend about a month looking for it, before they die. If they find it before then, they’ll crawl back underground near tree roots to lay their eggs before expiring. Their larvae, creamy white in color and growing up to 5 inches, then spends about3 to 4 years munching on distressed tree roots before emerging from their homes to begin the cycle all over again.
While these flying insects may look terrifying, they’re completely harmless. Once mature, they feed on fruit and nectar and while they are pretty harmless to other insects and animals, coyotes, bobcats, owls and others may find them to be a tasty treat. During their larval stage, those that may snack on them include coati, skunk, and even bears.
They are most active during the early evenings and are attracted to lights, so during their mating season, you may find them on your porch looking forlornly for other Palo Verde beetles to mate with.
There’s really not much you can do to ward off these beetles, besides investing in netting or screens for your porch or patio. Other than that, make sure the trees on your property and even immediate area are healthy with proper water and fertilizing, since their larvae don’t enjoy fresh, healthy roots and the beetles may end up looking elsewhere to lay their eggs.
If you’d like to enjoy a night out during these months when they’re most active, you may want to head to an indoor restaurant or bar instead. If riding a bicycle or a motorcycle during their mating season, make sure to always wear your proper safety gear and expect to encounter a Palo Verde beetle or two during your rides so you aren’t taken by surprise (and possibly get into an accident). If you like driving with the windows open or the top down during the evenings, consider avoiding these until after their mating season when they go back underground.