Monarch Monitoring Project - 10/18/08

The Insect of the Week

The Wheel Bug (Arilus cristatus)
Photo by Michael O'Brien


Hello everyone! It's time for another exciting "Insect of the week"! Meet the wheel bug! This alien-looking creature is one of the many types of assassin bugs that you might find in Cape May. When I say bug, I mean bug! Entomologists might yell at you if you call just any old insect a "bug." In taxonomy the word "bug" refers to anything in the order Hemiptera. The wheel bug, and many other things, fall into that order of classification. So, to review, here is the taxonomy of the wheel bug:

Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hemiptera
Family: Reduviidae
Genus: Arilus
Species: Arilus cristatus

So as you can see all insects are not indeed bugs, but all bugs are insects. Phew! Glad we cleared that up. The wheel bug is actually one of the largest true bugs in the world! It falls in the family Reduviidae which includes all "assassin bugs". Believe me, they are called assassin bugs for a reason. This cryptic killer hides itself on leaves or flowers, and much like the praying mantid, strikes quickly when it's prey lands nearby. As illustrated by the photo below:


The wheel bug, and other assassin bugs in general, attack prey with their long beak-like mouth parts called a rostrum. They stab the prey with their rostrum, and inject an enzyme which paralyzes the unfortunate captive. The enzyme also dissolves the insides of the prey on contact and allows the wheel bug to suck out the insides of the victim. It's like something from a horror movie!

Photo by Michael O'Brien


Wheel bugs also have some gruesome habits when it comes to mating. Like the mantid, the female wheel bug will often attack and consume the male after mating. Once fertilized the female will lay her eggs and eventually she will die. The eggs will hatch into tiny nymphs. Assassin bugs, as well as all Hemipterans and many other insects, go through incomplete metamorphosis. This means that they have only three stages of life: the egg, the nymph, and the adult. The monarch, and many others, have four stages of life and go through complete metamorphosis.



Photo from BugGuide.net


The nymph (see above) is like a smaller version of the adult but it lacks wings. The nymph will eat continuously and, like the monarch caterpillar, undergo five different molts (or instars) before molting into an adult. There have been records of cannibalism in wheel bugs, and freshly hatched nymphs may attack and feed on each other. If you find a wheel bug in the wild be careful! Their bite is extremely painful, and the sore can last for several weeks. They also are capable of emitting a stinky smell from scent-sacs located on the back of their abdomen. So this is perhaps another insect you might want to leave alone!

No comments:

Post a Comment