There’s been some serious buzz about the Brood X cicadas that are emerging at this time in some parts of Pennsylvania, Maryland and New Jersey, our ears humming with the incessant buzzing sounds of billions of cicadas as they emerge from underground for the first time in 17 years. Perhaps to our chagrin, this buzzing should stick around for four to six weeks while these insects mate and then ultimately die, all in a short span of time. All of this activity depends on when soil temperatures rise to at least 65 degrees.
Cicadas are large, noisy insects that people often mistakenly refer to as locusts. Cicadas are distant relatives of aphids (small sap-sucking insects) and stink bugs and have been around for roughly 150 million years. As a larvae, they live underground, feeding on plant roots. As adults, they emerge from the ground and do not feed. Rather they have a two track mind, they produce sound to attract mates and reproduce. Although the buzzing from a swarm can reach up to 100 decibels (about the sound of a gas lawn mower or tractor) can be annoying, cicadas do play an important role in the food web. “They provide necessary pulses of food rich in nutrients that sustain many populations of organisms from other insects to fish to mammals and birds,” says Dr. John Wallace, professor of entomology at Millersville University.
Cicadas are not a danger to humans, but they are damaging to trees. The larvae feed on their roots and the adults damage tree branches when they lay eggs. Where there is a large concentration of cicadas, the outer reaches of tree branches will typically die. This branch mortality is due to how cicadas lay eggs: they stab the tree bark, causing some serious damage.
Almost 3,400 species of cicadas exist worldwide, but periodical cicadas that emerge every 13 or 17 years are unique to the eastern part of the United States. The 13-year cicadas are found in the South, while the 17-year cicadas live in the North. Brood X is the largest of the 12 broods of 17-year cicadas, which emerge in different years.
As we prepare for the boom of cicadas, Wallace reminds us to, “Enjoy the splendor of insects and nature and appreciate the fact we still have them flying around and singing to us.”
Wallace is working with collaborator Tadhgh Rainey of Hunterdon County Vector Control Program in Flemington, NJ and Dr. Scott Starr (MU’08) from Ann Arbor, Michigan – a former Wallace lab member, both of whom are at the northern and eastern limits of the Brood X distribution. All are collecting larval burrow soil, larvae, teneral or newly emerged adult cicadas and older cicadas for a study that Wallace designed to examine microbial community differences in suburban yard and wooded habitats of cicadas from geographically distinct regions of this once in-every-17-year emergence. Wallace has also teamed up with his long-time microbiome collaborator, Dr. Eric Benbow at Michigan State University where all four scientists will be examining more closely changes in cicada soil and internal microbiomes over an even longer-term study where their study subjects show up every 17 years.
“While serendipity has presented us with a unique opportunity to do some unique entomological research, I hope that serendipity does not influence whether I’m around the next time they emerge so I can continue this work,” Wallace chuckled.