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Research Confirms: (Insect) Moms Are the Best

earwig with eggs

A mother earwig (Forficula auricularia) guards her nest of eggs. A recent study shows that earwig mothers return to their nests more quickly in environments with pathogens than in pathogen-free areas, to spend more time cleaning their eggs to protect them from potential infection. (Photo credit: Tom Oates/Wikimedia Commons, CC BY-SA 3.0)

By Adrienne Antonsen

Adrienne Antonsen

Adrienne Antonsen

Insects are exceptionally skilled at developing adaptations to increase their evolutionary success. One way to promote a species’ survival is through effective parenting, and in some standout insect species mothers go the extra mile for their young.

Some well-known insect supermoms include lace bugs, who will jump on predators and sacrifice themselves to protect their developing offspring, and Strepsiptera, whose mothers are eaten from the inside out by their young. In honor of Mother’s Day, here are some exciting new research discoveries in entomology about insect mothers that go to awe-inspiring lengths to care for their babies.

Earwig Moms Take Extra Care of Eggs at Risk of Pathogen Exposure

Earwigs make great mothers. They have previously been lauded for their devout commitment to protecting their young, spending months watching over them without food and moving their entire nest of babies if threatened. Now, research shows that earwig mothers can even sense the presence of dangerous pathogens in the environment and increase their level of parental care accordingly.

After briefly leaving their nest in response to a predator, earwig moms (such as the one pictured atop this post) returned quicker in environments with pathogens than in pathogen-free areas. By rushing back to her young, an earwig mother gets to spend more time cleaning her eggs to protect them from potential infection. Due to mom’s extra diligence, earwig larvae reared in the presence of pathogens survive just as well as those without exposure.

Ancient Cockroaches Evolved a Novel Body Structure to Protect Their Eggs

Cockroach with ootheca

Mother cockroaches commonly lay their eggs within oothecae, an elongated protective structure such as the one seen extending from the abdomen in this female Periplaneta fuliginosa. Researchers in China recently discovered the oldest known cockroach fossils with oothecae, at 125 million years old. (Photo credit: Toby Hudson/Wikimedia Commons, CC BY-SA 3.0)

Cockroaches may be maligned by human society, but they deserve recognition when it comes to motherhood. Their predecessors possessed long ovipositors to lay eggs externally, but long ago cockroaches developed special structures called oothecae, external protein-based egg cases that females attach and carry around with them.

This development led to a diversification of reproduction modes in cockroaches, with some dropping their ootheca shortly after mating and others carrying them until the eggs hatch. Researchers in China recently discovered the oldest known cockroach fossil with an attached ootheca that dates back to the Early Cretaceous, 125 million years ago.

With the development of oothecae, cockroach mothers increased their offspring’s chances of survival by protecting them from threatening predators and dangerous conditions. The adaptation continued to change in some lineages, and some modern cockroaches now carry oothecae internally; meanwhile, one species has even become viviparous, eliminating the ootheca and giving live birth like most mammals do. The ootheca and its derivations exemplify yet another reason to marvel at the impressive survival ability of cockroaches.

Burying Beetle Mothers Defy the Odds When Facing Adversity

A burying beetle mother feeds her babies regurgitated food from the mouse carcass they are living on. (Video by James Hataway, University of Georgia.)

For burying beetles, home is where the carcass is. These fascinating creatures bury the remains of a small vertebrate corpse then mate and lay eggs within the crypt. Both the mother and father then tend their young together, feeding upon the carcass and regurgitating it for the babies to eat. In fact, burying beetles represent the earliest known example of active parenting on Earth.

While both parents help raise their offspring, the mothers are the heavy lifters. Researchers in the United Kingdom recently discovered that female burying beetles engage in more fights with intruders and are better able to defend their brood than males are.

In a separate study, scientists from the same research group also tested what would happen if mother burying beetles were handicapped. In most animal species, handicapped mothers provide less care to their young. But, to the researchers’ surprise, when lead weights were attached to the mother burying beetles’ bodies, the mothers actually spent more time provisioning food to their offspring. By consuming more food than their weight-free counterparts, the weighted mothers powered through their extra burden to provide even better care for their brood.

Flower Beetles Plan Ahead to Ensure Their Young Will Stay Well Fed

Flower beetle - Dicronocephalus wallichii female

Female flower beetles such as Dicronocephalus wallichii, native to Taiwan, Thailand, and China, make sure their young have enough food no matter what circumstances arise. (Photo credit: Udo Schmidt/Wikimedia Commons, CC BY-SA 2.0)

Flower beetles are a type of scarab found worldwide that typically don’t provide any parental care. One species, though, Dicronocephalus wallichii, bucks this trend by constructing intricate nests for its offspring. Females spend several hours on each individual nest, digging a hole in the soil and then filling it with cut pieces of dead leaves. Each nest houses just one egg. This effort results in this species of flower beetle laying far fewer eggs over time than other scarab beetles.

Scientists recently investigated if the dead leaves laid down by the flower beetle mothers influenced offspring survival and growth. The researchers reared flower beetle eggs on soil with either high or low nutrients and either with or without dead leaves. In the end, if larvae were raised on nutritious soil, they did just fine regardless of whether dead leaves were present. If, however, the larvae were raised on soil of poor nutrition, nearly all of them would die if no dead leaves were provided. So, it appears mothers of this unique species of flower beetle go to great lengths to provide their young with well-stocked nests in case the surrounding soil is of low quality. Thanks to mom’s hard work, these flower beetles can thrive in environments where others aren’t able.

Aphid Wasp Performs a Never-Before-Seen Maternal Care Strategy

Pemphredon wasp female

Mother wasps in the genus Pemphredon (such as the Pemphredon lugubris female shown here) lay their eggs within plant stems and provision their larvae with aphid prey for food. Some are known to return to supply fresh food to early-developing offspring, but a 2017 study by researchers in the Czech Republic discovered that mothers of the Pemphredon fabricii species do the same for late-stage larvae, in a new behavior they dubbed “late progressive provisioning.” (Photo credit: Nigel Jones/Flickr, CC BY-NC-ND 2.0, cropped from original)

Most bees and wasps lay eggs, leave some food, and then go on their merry way. Scientists recently discovered an anomaly, however, in the aphid wasp species Pemphredon fabricii. Mothers of this wasp species use abandoned plant galls previously created by fruit flies to house their young and then provide them with paralyzed aphids to feed on.

Researchers monitored nesting behavior of wasp mothers in the Czech Republic and found, to their surprise, mothers revisiting their nests late in their offspring’s development to provide them with additional food. While some wasps are known to return to early-developing offspring to supply them with fresh food, a phenomenon known as truncated progressive provisioning, none have ever been known to resupply their late-developing young with food. The scientists termed this new behavior “late progressive provisioning.” This discovery just goes to show how great insect mothers are at continually developing new ways to better care for their babies.

To all the moms out there—human or insect—happy Mother’s Day! You’re amazing!

Adrienne Antonsen is a graduate student in entomology at North Dakota State University. Email: adrienne.antonsen@ndsu.edu  

3 Comments »

  1. This is such a sweet article! Good writing, and a great take on thanking the moms out there in nature!

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