Cicadas and their killers link strands on the food web
Cicadas and their killers link strands on the food web
By Tyler Frantz
In nature, every day is a matter of life and death. Though it’s a stark reality to recognize, the food web offers proof that one organism must die for another to live. This web is intertwined by complex relationships of who eats whom, and it’s strands run far and wide.
There is no wonder that nature provides larger numbers of the “expendable” species- those that seem to fall into the prey category more often than that of the predator. Think about it- there are more plants than animals, more rabbits than foxes, more voles than owls and more salmon than grizzlies. This schema is not by accidental design. The same goes for the insect kingdom, where killing for survival is no different. This was most recently brought to my attention on a warm summer evening while grilling deer sausage on my brick patio, surrounded by cicada song.
Throwing links over a dancing flame, I closed my grill lid and took a step back just in time to observe the largest wasp I’ve ever seen in my life emerging from a small hole in the gravel between the bricks.
Admittedly, my first instinct was to grab a can of wasp & hornet killer, but in a moment of curious hesitation, I instead searched “huge ground-dwelling wasps” online. Much to my surprise and the wasp’s good fortune, I discovered that this interesting ground digger species, commonly known as the “Eastern Cicada Killer,” is extremely mild-mannered towards humans.
This instantly put me more in-tune with the extensive presence of cicadas surrounding my property, which until now, I had honestly paid little attention. The next day, I spotted a cast cicada exoskeleton on the post I use as a bow hanger on my backyard archery range, another in my driveway and two more on the limbs of a nearby white pine tree.
Interestingly, I hadn’t noticed these before, but then again, I wasn’t looking for them either. One morning, however, I caught a Cicada Killer in the act, as it struggled to haul in its hefty bounty- a large green bug nearly twice its size, which I later identified as a common annual “Swamp Cicada.”
This fascinated me, as many encounters in the natural world often do, so I had to learn more. In doing a little research, I discovered that Cicada Killers dig burrows for their nests, favoring loose, dry, sandy soils. Females do most of the work, meticulously building nests, laying eggs and hunting cicadas, which she paralyzes with her stinger before carrying them back to feed her young.
Males simply do their best to attract a mate- tirelessly jockeying for breeding dominance. They are more aggressive than females but cannot sting.
“Cicada Killers are really docile, actually,” said, Sinclair Adam Jr. of Lebanon’s Penn State Extension office. “Though they are probably our state’s biggest hymenoptera, they pose minimal threat to humans. A co-worker of mine has had them sit in his hand with no damage.” Their demeanor toward cicadas is a different story, however, as these wasps aren’t called Cicada Killers for nothing. They actually serve as a natural control of the annual and periodic singing insects, which emerge from their underground lairs in the adult form to mate and lay eggs, fueling the next generation of cicadas.
“In ecology, predator and prey populations often cycle in tandem,” said Adam. “The cicadas begin to emerge in late June and the wasps show up about a month later.”
It is almost ironic how many similarities the hunters share with the hunted. Like the wasps, Swamp Cicada females also do most of the work, while males simply attempt to attract a mate. The shrill, rapid chatter we hear buzzing in the treetops is likely a chorus of males vying for the romance of a female.
When successful, paired Swamp Cicadas mate, and then females lay their eggs on the underside of branches. A few weeks later, the soft-bodied nymphs fall to the ground and burrow into the tree’s root system, feeding on its sap until they are ready to emerge again as adults and repeat the cycle. Though they may cause occasional damage to trees, cicadas don’t pose an overwhelming threat to natural host vegetation.
“It’s all part of the food web,” said Adam. “Our native trees are pretty good at supporting insect life, which serves as a great food source for other wildlife. They help sustain one another- just as they have for many generations.”
“It’s important for people to realize that native plant species have co-evolved with native insects, and those insects have co-evolved with their native predators, such as the Cicada Killer wasps and the colorful songbirds we all love to see.”
“We get into trouble when we begin introducing exotic species that don’t belong as part of that natural food web ecosystem, such as ornamental yard plants that aren’t native to this environment. They don’t appeal as a food source to local animal species, so the natural harmony of control and sustenance is thrown into disorder.” This whole process of predator vs. prey, wasp vs. cicada, hunter vs. hunted really got me thinking. Perhaps we shouldn’t view it as a competition that pits one species against the other.
In reality, through life and death, these species really help one another thrive and co-exist. They are linked together like complimentary strands within the food web, one no better than the other, all just trying to survive and procreate.
It also further confirms my stance that as natives to our environment, we humans also have a place within that web -one that includes responsibly hunting, consuming, preserving and co-existing with our fellow web dwellers- because in the end, it really is a matter of life and death… isn’t it?
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