Fattest Animal

This cutworm moth (Family Noctuidae) is the fattest animal in the world. In just two summer months of feasting on flower nectar, the migratory moths balloon from 20% to 80% body fat (1). Storing this much energy has a price though – no romance. Migratory moths put reproduction on hold to save up energy for their journey.

Thanks to all that fat, cutworm moths are a major food item for grizzly bears in the summer (2).

It got me wondering: These moths delay reproduction so they can migrate, but putting on fat makes them more delicious. Why not just stay put and make some babies instead? Since their migration is basically east-west, major temperature/seasonal shifts don’t require the move*. Local plants (food) don’t require the move either **. Parasites might. Army cutworm moths are highly parasitized. Moths with parasites stay in the Rocky Mountains longer, growing larger and fatter. So the bears may do the whole population of moths a favor by culling those with parasites.

* Altitude is a factor in temperature and season. But if moths stayed near the mountains, they could stay put moving up and down in altitude without flying a few hundred miles to and from the plains.

** Larvae eat a wide range of leaves and stems. Adults suck up flower nectar. So a large number of larvae may reduce some food for the adults.

1. Kevan, PG and DM Kendall. 1997. Liquid Assets for Fat Bankers: Summer Nectarivory by Migratory Moth in the Rocky Mountains, Colorado, U.S.A. Arctic and Alpine Research 29(4):478-482
2. French, SP, MG French and RR Knight. 1992. Bears: Their Biology and Management. p 389.

Chirpless: Camel Crickets

Camel crickets (Ceuthophilus sp.) enjoy hanging out with humans. Perhaps you provide shelter to some in your garage or basement. These insects lack one major cricket trait though – chirping. Sound production should allow camel crickets to find each other in a dark cave or crawlspace. So, why no chirps?

A Chirp Mystery

One possible reason for the lack of chirps is a high risk of predation. In other species of crickets, those who call more or longer often end up as a snack. ^{1, 2} While I would hope camel crickets are relatively safe from bats and birds in your basement, spiders and mice are the crickets’ major predators. Both possess a solid sense of hearing.

Many crickets have parasites who also seek hosts by sound. Chirps attract female crickets, but they also draw mama parasites searching for a cozy spot to lay eggs. The developing parasitic larvae eat the cricket from the inside, exploding out of its body as they grow. Crickets in areas with these parasites quickly evolve “chirplessness.” Do camel crickets need to worry about these “Alien” chest-bursting scenes? While they do have a doozy of a parasite (an intestinal parasite that weakens the cricket enough to ensure predation), the infections are not related to sound production.

Perhaps camel crickets simply lost their physical ability to chirp. Most crickets produce sound by rubbing their wings together. Camel crickets, though, don’t have wings. In a basement, flying is probably not the most effective means of transportation.

The Scent of a Cricket

So, how do camel crickets find each other without sound? One word: pheromones.

Pheromones are used by many cricket species to indicate dominance, reproductive readiness, and location. Camel crickets release a scent that causes them to congregate. Researchers determined the pheromone is unrelated to reproduction since juveniles move toward the scent too. Nagel and Cade³ think the pheromone prevents camel crickets from drying out. We do know the antennae detect these pheromones. In a rather disturbing experiment, researchers found that camel crickets don’t aggregate when their antennae are lopped off.

 

1. Baily, W.J. & Haythornthwaite, S. (1998). Risks of calling by the field cricket Teleogryllus oceanicus: potential predation by Australian long-eared bats. Journal of Zoology. 244(4) 505-513.
2. Hedrick, A.V. (2000). Crickets with extravagant mating songs compensate for predation risk with extra caution. Proceedings of the Royal Society B 267(1444) 671-675.
3. Nagel, M.G. & Cade, W.H. (1983). On the role of pheromones in aggregation formation in camel crickets, Ceuthophilus secretus (Orthopter: Gryllacrididae). Canadian Journal of Zoology 61(1).

The Firefly and the Apes

An old Philippine folktale pits a firefly against a troop of apes. One day, an ape asks the firefly why he carries a lantern. The firefly replies that he uses the light to see mosquitoes and defend himself. The ape laughs and calls the firefly a coward. Insulted, the insect challenges the ape (and all his friends) to a fight. The next day, the firefly faces 1000 apes with large clubs, all lined up against him. The firefly lands on the first ape’s nose and the second ape swings his club to squash the insect. But the lightning bug flits away and the ape’s blow kills his companion instead. Then the firefly alights on the second ape’s nose. A club is swung and the second ape is dead. On and on until the firefly reaches the last ape, who piteously surrenders. The folktale ends, “Since that time, the apes have been in mortal terror of the fireflies.” (1)

Despite folktales consistently portraying apes as fools, we all know they’re actually pretty smart. The Philippine tale is one account of why apes avoid fireflies. But could there be a biological reason for this aversion? Maybe it’s because fireflies are noxious.

One firefly can kill a bearded dragon (Pogona sp.), a fairly large lizard that can grow up to 2 feet long (2). For mammals like apes, well, they probably just taste really bad. Most animals that eat fireflies spit them out or throw them up.

Fireflies do try to warn their would-be attackers through their coloration. Light and dark stripes and red markings are examples of aposematic coloration – both are found on this lightning bug. Don’t say he didn’t warn you!

 

1. Millington, WH and BL Maxfield. 1907. Visayan Folk-Tales. Journal of American Folklore. 20(79) 311-318.
2. Knight, M et al. 1999. Firefly Toxicosis in Lizards. Journal of Chemical Ecology. 25(9)

A Raspberry’s Worst Nightmare

With all the beautiful berries available now, I’ve been seeing more fruit flies hanging around the kitchen. Annoying? Yes. Ruining my strawberries? Nope. Fruit flies lay their eggs on damaged or rotting fruit. So they’re only interested in the pieces that are going bad. I’m ok with that.

But consider a fruit fly who lays her eggs on fresh fruit. She’d have the agricultural community freaking out. Just imagine the risk to berry crops. Actually, you don’t have to imagine because scientists have already done the calculations for you: it’s potentially $2.6 billion of risk (1).

Evolution has already dealt this stunning set of cards to Drosophila suzukii, the spotted-wing drosophila (2). The females have an ovipositor (the anatomical structure that deposits eggs) that looks like a serrated knife. Unlike the common fruit fly in your house, this species’ egg-laying parts can cut through the skins of raspberries, strawberries, blueberries, cherries, and grapes.

Want to learn more about the spotted-wing drosophila? IFAS at the University of Florida has a great info page on the little beastie (with horrifically gorgeous pictures, by Martin Hauser, of that ovipositor – if you haven’t seen fruit fly genitalia yet, you are missing out).

p.s. Thanks to Dr. Nadia Singh for introducing me to Drosophila suzukii.

1. Walsh, Douglas, M. Bolda, R. Goodhue, A. Dreves, J. Lee, D. Bruck, V. Walton, S. O’Neal, F. Zalom. 2011. Drosophila suzukii (Diptera: Drosophilidae): Invasive Pest of Ripening Soft Fruit Expanding its Geographic Range and Damage Potential. Journal of Integrated Pest Management. 2(1): G1-7.

2. Atallah, L. Teixeira, R. Salazar, G. Zaragoza, A. Kopp. 2014. The making of a pest: the evolution of a fruit-penetrating ovipositor in Drosophila suzukii and related species. Proceedings of the Royal Society B: Biological Sciences, 281 (1781)

Bee Bandits

Flowers need bees. A bee’s job is to move pollen from one bloom to another; plants pay for the bee’s service with sweet nectar. Cunningly, some bees have found a way to get a paycheck without the work.

Carpenter bees (Xylocopa sp.) exhibit a behavior called “nectar theft.” Rather than reaching the base of the flower through its opening (and getting a pollen dusting in the process), robber bees bite a hole in the base of the flower to slurp up nectar, bypassing the pollen-yielding anthers entirely.

We can’t necessarily blame them though, as it may be the plant’s own darn fault. Flowers with long tube-like bases are more likely to get robbed since the brawny carpenter bees can’t reach the nectar any other way (1). This relationship may even keep the flower tubes shorter over evolutionary time, since short flowers are more likely to be pollinated (and less likely to be robbed).

In order to deter break-ins, some flowers have evolved thicker flower walls, new toxins, or even special relationships with animal “special forces.” Some tropical flowers produce extra nectar in a special chamber for ants, who act like police in stopping the robber bees (2).

P.S. The bees I watched for this sketch were upstanding citizens – no thievery going on here!

P.S.S. It’s a girl! This bee’s got a black face. Males have a large patch of white on their faces. (http://www.uark.edu/ua/arthmuse/carpbee.html)

1. Navarro L and R Mendel. 2009. Relationship between floral tube length and nectar robbing in Duranta erecta L. (Verbenaceae). Biological Journal of the Linnean Society. 96 (2) 392-398.
2. Gerling D, HHW Velthuis, and A Hefetz. 1989. Bionomics of the Large Carpenter Bees of the Genus Xylocopa. Annual Review of Entomology. 34:163-190.

 

Is Your Favorite Animal a WUG?

Think of your favorite animal. Is it warm and fuzzy? Or fine and feathered?

Many people think of “animals” as mammals, birds, or reptiles. Occasionally a fish, crustacean, or insect will creep in there. But, let’s face it, our view of animals is limited.

Children reflect this discrepancy when asked to draw a picture of a habitat. For instance, Snaddon et al. (2008) found that children drew ~75% mammals, birds, and reptiles in their portrayals of a rainforest. In reality, rainforest animals are 90% insects.

The rainforest isn’t unique. Most animals are insects (beetles, to be specific). It makes the Victorian hobby of beetle-collecting seem a little more understandable now.

And the Nematodes! Nematodes (roundworms) make up a surprisingly high percentage of animal species. Scoop up a trowel-full of soil from your yard, and you’re likely to have thousands upon thousands of nematodes in there.

If we can get children to understand that ecosystems, like rainforests, contain more animals than just vertebrates (and plants too!), the consequences include a better understanding of ecosystem functions and conservation issues.

So introduce yourself and your children to insects and worms (sometimes called “wugs” – worms and bugs). Attend insect-related events at a museum, make insect-face masks for play, visit natural environments, sow insect-promoting native plants (and keep careful track of all the worms in the ground), or tend an insect or worm as a pet for a couple days.

Maybe your new favorite animal won’t have fur or feathers.

 

Snaddon JL, Turner EC, Foster WA (2008) Children’s Perceptions of Rainforest Biodiversity: Which Animals Have the Lion’s Share of Environmental Awareness? PLoS ONE 3(7): e2579. doi:10.1371/journal.pone.0002579

Winter’s “Toasted Marshmallow” Egg Case

This “toasted marshmallow on a stick” is the egg case of a Chinese Praying Mantis (Tenodera sinensis), containing hundreds of developing youngsters. The eggs overwinter in this protective case until the spring’s warm weather triggers the eggs to hatch into tiny nymphs (mini-mantids). Nymphs grow into adults who enjoy their summer, snacking on any and all insects who cross their paths. In the fall, Praying Mantises mate, lay their eggs, and pass away.

A female mantid’s work may all be for naught if a tiny parasitic wasp interferes. The mantis lays her eggs in a frothy matrix that hardens around her offspring; but this mini wasp (sporting a ridiculously long ovipositor and rear legs that look like the mantids’ front legs) can lay her eggs inside the mantis case before it hardens. Since the wasps hatch first, they’ll use the mantis eggs as food.

Thanks to Mike Dunn (Roads End Naturalist) who recently presented a guide to winter wildlife – tracks, chew marks, and insect sign. Not only was I awed by his amazing photos, Mike also brought samples of all sorts of wintertime insect egg cases (including this one), cocoons, nests, tracks and galls.

Five Reasons Why This Beetle Should Win the Best Insect Award

I recently ran across this gorgeous beetle while hanging out with writer Scott Huler on his ambitious Lawson Trek. I didn’t know what species it was, but figured it would be pretty easy to ID when I got home (it was). As I began researching this insect, I quickly realized that the Patent-Leather Beetle (Odontotaenius disjunctus) should be nominated for a Best Insect Award.
Here’s why:

1. Great Personality
This very large beetle with scary looking mouthparts won’t hurt you. It rarely flies and it’s a pretty slow walker… so no sudden movements and no buzzing around your head. I like that in an insect. And those horrifying chompers? They’re used to chew through logs, not people. Thank you, evolution.

2. Cool Appearance
Ooo, shiny! Plus, it’s a terrific insect for anatomy practice. First, no microscope needed. Second, that clear-cut case of head, thorax, abdomen? Not so fast. The abdomen-looking structure is actually a grooved set of hardened wings called elytra. And that thorax-looking structure? Well, it is PART of the thorax. The other section is underneath those elytra. Way to keep things interesting!

3. No Sexism
Both males and females contribute to rearing their young and keeping the home safe and tidy. This social structure is not common among beetles (see another post about equality-minded beetles).

4. Ecological Service
Patent-leather beetles don’t just raise their family in logs. They also eat and decompose the wood, recycling nutrients back to the forest floor.

5. Kiss Language
These beetles communicate with each other through a number of different calls. Many calls sound like the noise you make when blowing someone a kiss. Larval patent-leather beetles even have a modified third set of legs that create noises to communicate with parents (“Ma, I’m hungry!” “Watch me, Dad!”)

Want to learn more about the awesome Patent-leather beetles (and hear their kiss-calls)? Here’s a great resource from the University of Florida.

Oak Scale – Sitting There Like a Tiny Bump on a Log

See that tiny bump on the branch? You’re looking at a mom protecting hundreds of babies. Well, actually, the mama Oak Scale insect (Parthenolecanium quercifex) is dead now, but her exoskeleton is still harboring those little eggs underneath. When those baby Scales hatch around the end of May, the tiny darlings will move out to the oak leaves and begin to SUCK THAT POOR TREE DRY. They sniff out the precious sugar-water flowing through veins in leaves, insert their straw-like mouth parts and drink up. As the year progresses, Scales grow and mate. Mama lays her eggs beneath her and dies, making way for next May’s new generation.
(These are the eggs… um, on my kitchen table. Didn’t realize they’d pop out like that when I lifted the mama Scale off. Oops.)

In the insect’s defense, healthy trees can resist Scale infestations. Some leaves and twigs may fall off – that’s all. But trees that are weakened (by physical damage, drought, chemicals, etc.) can be killed by the insects.

Cool Climate Change research recently found that densities of Oak Scale are up to 13x higher in warm urban areas! (1) Since things are getting toastier here on Earth, we may want to get more familiar with the life & times of the Oak Scale.

1. Meineke EK, Dunn RR, Sexton JO, Frank SD (2013) Urban Warming Drives Insect Pest Abundance on Street Trees. PLoS ONE 8(3): e59687. doi:10.1371/journal.pone.0059687