Environmental Almanac

Exploding insects top bill at this year’s Insect Fear Film Festival

Fictional critters have nothing on these real-life wonders.
Purple and orange on black drawing of a giant cockroach racing away from an exploding volcano.

A crop of the t-shirt design for this year. design by Chip Austin

In anticipation of the 33rd Annual Insect Fear Film Festival, which they will host Saturday on the U of I campus, this week’s commentary comes from three members of the Entomology Graduate Student Association : Josh Gibson, Todd Johnson, and Tanya Josek. Believe it or not, they’re here to talk real-life insects that explode.

Bombardier beetles (Todd)

One day Charles Darwin was returning from a collecting trip when he spotted an interesting beetle. His hands were full so he decided to transport it in his mouth. There, the beetle released an explosive chemical reaction causing Darwin to drop all of the insects he collected that day. We now know these insects as bombardier beetles, which get their name from a unique ability to direct a hot spray of chemicals from their posterior end. Recently, researchers found that these beetles open and close a valve inside their body while spraying, causing the spray to come out in a series of pulses. The pulses probably help protect the beetles from damaging themselves by limiting their exposure to the reactive chemicals. For bombardier beetles this is a very effective defense against predators looking for a quick meal.

Exploding ants (Josh)

In the forests of southeast Asia, it’s an ant-eat-ant world. Tree-dwelling ant communities are often dominated by species with large, aggressive colonies, which can make it difficult for others to establish nests. To do so requires a good defense . . . but sometimes a good defense is a good offense. Exploding carpenter ants have evolved a unique way of defending their nests from attack. When threatened, the workers of this species can compress their abdomens and cause dangerous chemicals to burst from their heads. This often kills nest intruders at the cost of the workers’ own lives. The ruptured ants stop scouts of more aggressive ant species from informing the rest of their colony of this valuable nest location, preventing a large-scale invasion. By sacrificing their own lives for the good of the colony, exploding carpenter ant workers allow their colonies to stand tarsus-to-tarsus with more aggressive ants and live to tell the tale – even if some of the workers themselves do not.

Parasitoid wasps (Tanya)

The science fiction hit Alien terrified audiences with the idea of aliens bursting out of astronauts. While most of the movie is fiction, some of the biology is not. Right here on earth, many arthropods are susceptible to attack by parasitoids, insects that develop while attached to or inside them. For example, there’s a certain tiny wasp female that seeks out tobacco hornworm caterpillars. When she finds one, she uses her stinger to inject eggs inside it. The caterpillar continues to eat and grow, unaware that wasp larvae are growing inside its body. Once the larvae fully develop, they chew their way out of the caterpillar’s body and spin cocoons, eventually emerging as adults. Shockingly, the caterpillar is alive throughout this entire process and only dies after the wasps have completed development.

Of course, if you think this stuff sounds wild, wait till you see the mutant cockroaches and gigantic, lava breathing  tarantulas in this year’s films. Doors to Foellinger Auditorium open at 6pm with an insect petting zoo, face-painting and balloon insects, insect-related artwork, and our first ever “talking cockroach.” Find further details http://www.life.illinois.edu/entomology/egsa/ifff.html