Litinsects

Dragonfly wings Dipteran (fly) wing Monarch butterfly wing Lacewing wings Litinsects #34: Insect Wings Let’s talk wings. The ability to fly has existed in only 4 groups of animals: birds , bats , pterosaurs , and of course insects . The first three groups, all vertebrates, each evolved flight independently (in other words, they have no winged ancestor in common) and the wings replace a pair of limbs. Insect wings on the other hand, which first showed up around 400 million years ago, are not derived from legs but are completely separate structures. The big debate about the evolution of insect wings is whether they developed from pre-existing structures (like gills or extensions of the thorax) or were entirely new structures. There is very little fossil evidence documenting this evolutionary transition so no one has yet definitively answered this question... Insect wings attach to the second and third thoracic segments. At rest they may be held vertically over the back, horizontally ou...

© Günther Matula Litinsects #28: Odonata Dragonflies and damselflies (both not actually flies) make up the order ODONATA, meaning “toothed ones”, which refers to the insects’ strong and sharp mouthparts. This is one of the most primitive orders of winged insects! Odonates are further categorized into two infraorders, the dragonflies and the damselflies. Dragonflies belong to ANISOPTERA, from the Greek anisos for “unequal” and pteron for “wing” because their front wings are slightly narrower than t heir hindwings (just check out the first picture). Damselflies belong to the infraorder ZYGOPTERA, from the Greek zugos meaning “even” because both wing pairs have the same shape Damselflies are generally daintier looking, while dragonflies appear more robust. An easy way to differentiate between the groups is how they hold their wings at rest: dragonflies hold them open and out to the side while damselflies hold them closed and upright over their backs (see t...

Litinsects #4: Simple Eyes Yesterday I talked about compound eyes, the multi-faceted structures that most insects use to see the world 👀 But insects actually have another visual system as well, composed of simple eyes or OCELLI. Unlike compound eyes, ocelli are composed of only one structure which makes them comparatively “simple” although they are still very important. These are light-detecting organs consisting of a single lens with sensory cells. They can detect movement but don’t form complex images. “Ocellus” comes from the Latin word oculus, meaning eye. So these structures are literally “little eyes” Ocelli are located on the insect’s head, usually between or adjacent to the compound eyes. They are usually dome-shaped, somewhat shiny structures In most flying insects (such as flies, dragonflies, bees, etc.) there tend to be three ocelli in a triangle arrangement (see photo). Some terrestrial insects (like cockroaches) have only two ocelli ...

Litinsects #1: Dragonfly Wings Ever wondered why dragonflies have this dark cell at the front of their wings? This is called a PTEROSTIGMA. This thickened cell is heavier than the rest of the wing, so scientists believe it helps the insects in gliding by reducing vibrations in the wing. Pterostigmata are found in all dragonflies and damselflies and a few other insect groups. And now for some FUN FACTS about dragonfly wings: Dragonflies are one of the FIRST groups of winged insects to evolve! The shape and vein patterns of dragonfly wings can be used in species identification Dragonflies can operate their fore and hind wings INDEPENDENTLY (which almost no other insects can do!) This gives them a level of control and agility that makes them amazing aerial hunters The globe skimmer dragonfly makes an annual multigenerational migration of 18,000 km (11,000 mi), the LONGEST of any insect Dragonflies and damselflies are easily distinguished by their...