Story last updated at 10/30/2013 - 6:59 pm
Insects are abundant anywhere you look outdoors in Southeast Alaska if you look close enough. Oddly enough, both Alaska Forest Service Entomologist Elizabeth Graham and Alaska Fish and Wildlife Service Biologist John Hudson compared many of their habits and features to scenes from the movie “Alien.”
Even with the insect’s uniqueness, they serve an important role in the food chain — from pollination to feeding other animals and so much more.
Here are some important, interesting, and just plain weird bugs you could see in Southeast.
They help sustain salmon stocks and are crucial to their early development. These include stoneflies, mayflies, caddisflies and others, said Hudson, who specializes in aquatic insects.
“That’s an economic importance,” he said. “They sustain those salmon.”
Hudson’s passion is studying dragonflies, which have some pretty interesting abilities besides being beautiful. Dragonflies are predatory insects, which prey on things like mosquitoes and black flies, Hudson said. Hudson said dragonfly larvae are probably what the makers of “Alien” modeled their characters after.
Dragonflies have a lower lip that’s highly modified — it’s used to grab things. It’s hinged and extendable and also uses hydro pressure so it can grab prey in 1/100 of a second. It also has palps (a teeth-like structure).
If its method of catching their food isn’t enough to impress you, just wait until you hear that it also breathes through its butt. Hudson said the dragonfly has gills in it’s abdomen. This is where it gets even wilder. The dragonfly has an ability to do ballistic defecation. It uses its muscles in its abdomen to suck water in and out — and can force that water at a very high speed out of its butt. For what purpose? Two actually. One — to jet propel itself across water; two — to clear away its excrement so it can stay in “stealth” as it waits for its prey. Hudson said it’d be fun to create a Halloween costume that can do what a dragonfly can.
This maggot lives in and feeds on dead, organic matter. Given that the matter is low in oxygen, this little critter has a telescopic breathing tube it can extend two to three times its body size so it can breath air outside of its oxygen-free home.
If you take a close enough look at a pond or other mellow body of water you may see a rippling of the water surface. What’s likely to be the cause is a whirligig beetle, which can kicks it’s legs 60 times per second as an adult.
“They create these little waves on the surface, which they use to echo-locate prey,” Hudson said. “They’ll communicate with each other that way.”
They also have two sets of eyes — one on the top of their head, and another on the bottom. This is so they can see prey both above and below the surface.
Hudson said we don’t see fish eating these insects because of a defense mechanism where the beetle will excrete a “very distasteful” fluid.
“So when a fish catches one, (the beetle) will excrete the fluid and the fish will cough it out,” Hudson said.
This is an elongated insect that doesn’t have any legs. It’s considered a true fly because of its leglessness. Hudson finds it interesting because it has antennae that are not used to collect information, like most insects do with antennae. Instead it grabs things with them. They’re also almost entirely transparent with no pigment. They will sit in a water column by using their air-filled sacs, which help them move up and down the column. The antennae will bring the midge’s prey directly to its mouth, and the prey doesn’t see it coming. They’re typically found in muskeg ponds and if you watch close enough you’ll typically find them in groups.
Fireweed Hornworm Caterpillar
This juicy guy was seen a lot this summer feeding on fireweed.
“It’s really, really big,” Graham said. It will turn into a hawk moth.
The fireweed hornworm also serves as a pollinator.
Graham specializes in wood-boring beetles, and there is a family of wasps that is basically a parasite to these beetles.
“Almost all insects have some kind of parasitoid,” Graham said. She referenced the movie “Alien” and said that some of the action is based off of parasitoid behavior.
“The adult wasp will sting the beetle or whatever and lay their eggs inside the beetle,” she said. “The eggs will hatch and the larvae will feed inside the beetle. The beetle is still alive, and it basically will burst from the inside out. That’s when the new adults emerge.”
The wasps can hear the beetles chewing on the wood inside the tree, and will take their ovipositor and strike through the bark, hitting the beetle inside.
“I would consider them a beneficial insect because it kills a pest,” Graham said.
Green/ Striped Alder Sawfly
The parasitoids are useful, Graham said, because it helps keep native insect populations in check. There are periodically outbreaks of certain kinds of flies, the parasitoids will rebound as well and take the overwhelming population back down. Graham said this is why the introduction of exotic species is so dangerous — there typically aren’t any or enough predators and the new species spreads quickly — like with the green alder sawfly and the striped alder sawfly. They’ve been spotted in Juneau, Sitka and Ketchikan, and Graham believes they’ve probably been here for a long time now. She said they’re sort of like caterpillars except they turn into a wasp instead of a butterfly or moth. They feed on alder needles.
Another forest pest Graham has studied is the leaf beetle. They’ll be found in little masses and have tiny white spots on them. These white spots are stink glands, and as soon as the beetle is disturbed it will force out the stink glands as a defensive response.
Bumblebees are very important to Southeast Alaska (and almost everywhere on earth). They pollinate our flowers and fruits.
“There’s so much food that we rely on bees for,” she said.
Other insects have caught on to the defensive abilities of the bumblebee, like the hoverfly. It not only mimics the bee’s warning colors — yellow and black — but it’s also mimicking the bee’s entire lifecycle. They emerge in the early summer, after the baby birds have learned that the yellow and black insects are not pleasant to eat. The hoverfly is also a pollinator.