There are a few orders of insects that I want to cover, and this being the last of the five passion blog posts, I’ll squeeze three into one. These three are Orthoptera (crickets and grasshoppers), Blattodea (cockroaches), and Odonata (dragonflies and damselflies).

Orthoptera, meaning “straight wing”, refers to the narrow, leathery forewings that grasshoppers and crickets possess. Similar to Coleoptera (the beetles), insects in the order Orthoptera do not use these forewings for flight. Instead they are used mainly for protection, and in the case of some males are rubbed against their hind legs to create sounds. All insects in this order are salutorial, meaning that their legs are adapted primarily for jumping. The enlarged hind legs are one of the most distinctive features in identifying this insect in the field.

Another identifying characteristic about these insects are the way they feed. All Orthopterans have large chewing mouthparts protruding from the underside of the head which they generally use to eat foliage or other insects. Because of their normally large size and their conspicuous mouthparts and legs, grasshoppers are often used as models for the basic insect anatomy. In fact, I got to dissect a large lubber grasshopper in entomology lab and observe its external anatomy.

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Cockroaches of the order Blattodea are one of the oldest (and one of the most feared) species of insect around. These flat, shiny insects scuttle into corners of basements, bathrooms, and kitchens alike. It is a commonly held belief that cockroaches can give you diseases because they inhabit places of filth, but cockroaches cannot transmit any human diseases. They can, however, deliver a nasty bite so I would avoid picking them up with your hands.

I have had many encounters with cockroaches (luckily none have ended in bites) and they are one of the most interesting insects to look at. I once observed an Oriental cockroach that I had found in the school bathroom and trapped in a Ziploc bag. The way that its legs moved and its antenna patted around the clear walls was fascinating and I found it hard to look away. I found a dead American cockroach on the floor of the bathroom in Atherton last semester, and I kept it to pin later (I like to freak my roommate out with it). Additionally, in entomology lab I dissected a hissing cockroach to inspect the internal anatomy. They are a good model because their undersides are fleshy and easy to cut into and their organs are long and sectioned off well for studying.

And yes, they can live for over a week without their head, but then again, most insects can live for short periods of time without their heads due to the fact that they have an open circulatory system and a series of small ganglia (like mini brains) running throughout their body.

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The last order of insects that I want to mention is Odonata, arguably one of the most aesthetically pleasing orders. Although dragonflies and damselflies with their crystalline wings and long, slender bodies may look delicate and beautiful, they are actually ravenous hunters. Practically every bit of anatomy on the dragonfly’s body has to do with its predatory nature- their thin, dangling legs are more adapted to hold prey than to walk and they have razor sharp mouthparts to cut into their prey. Even the naiads (aquatic immature forms of the insect) have a sharp lower lip that can shoot out underwater and catch other aquatic insects or even fish.

The differences between dragonflies and damselflies is relatively easy to identify even by the amateur eye. Damselflies tend to be smaller than dragonflies, and thinner as well. In addition, while dragonflies hold their wings flat out to the sides when they land, damselflies fold their four, thin wings up behind them when resting.

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Image Citations: Grasshopper, Cockroach, Dragonfly