Biodiversity – Oct. 29/12
- Order Diptera – Flies: Di means two and ptera means wing, so these are two-winged insects. A
synapomorphy for the Order Diptera is the hind wings modified/reduced into knob-like structures
called halteres. All flies have halteres. Halteres are flapped up and down during flight, as wings are.
The base of the haltere sits in a nerve-filled socket and sends complex messages to the brain about
flight position. It acts like the gyroscopic flight indicator on planes. It helps balance and stabilize the
fly during flight. Flies are sometimes called true flies to distinguish them from other insects that have
the word fly in their common name (ex. dragonflies, dobsonflies).
- What is a fly?: Flies undergo complete metamorphosis. Halteres are a synapomorphy of flies. Adult
produces egg, which becomes larva (maggot), which becomes puparium, which becomes adult. The
larvae of basal flies are varied. The larvae of advanced flies are maggots, which are featureless
feeding machines with chewing mouthparts. They live in their food. They live in and eat rotting
organic matter from plants and animals. Most larvae are aquatic. The puparium is like a cocoon, and
the pupa is located inside. Adult mouthparts are highly modified for various types of liquid food, for
example sponging liquid, lapping blood, sucking blood. There are no chewing mouthparts in adults.
There are 150,000 described species of flies worldwide. Many adults are day-active (diurnal). Many
adult flies are important pollinators, stopping at flowers to drink nectar and fuel-up for flight. For
example, Theobroma cacao is pollinated by a fly. The science of genetics was built on the “lab rat” fly.
Because of the few species of biting flies, some which transmit diseases to humans, and the pesky
house fly, flies are hated by most people. But flies were instrumental in building the science of
genetics and many are important pollinators of flowering plants. They are excellent fliers. Only some
primitive flies are blood-sucking. Examples of primitive flies are mosquito (Culicidae), crane fly
(Tipulidae), moth fly (Psychodidae), and non-biting midge (Chironomidae). Aquatic larvae are an
important food source for other aquatic animals. The more larvae there are in water, the better the
water quality (shows there’s no pollution). In derived flies, antennae are reduced.
- Family Culicidae – Mosquitos: There are 3000 described species worldwide. This is an extant basal
fly group. Adult females have long needle-like serrated mouthparts with a central sucking tube. They
required blood for egg development. Eggs are laid in standing freshwater. Larvae are air-breathing.
The have organs at the tips of their bodies that breathe in air. This is why they need to be in standing
water, because if they were in fast-moving water, they wouldn’t be able to get air. Larvae are an
important food source for aquatic animals such as fish, amphibians, and insects. Bats, birds, and
amphibians eat adult mosquitos. Mosquito-borne diseases include west nile virus and malaria. The
mosquito anti-coagulant saliva causes us to itch. The saliva also transmits Plasmodium. Mosquito
eggs are laid in salt marshes, freshwater marshes, bogs, ponds, lakes, and puddles with standing
water. Larvae feed on algae, organic debris, microorganisms, and sometimes on other larvae. It is
important to look at the ecological function of all life stages.
- Family Tipulidae – Crane Flies: There are 4500 described species worldwide and this is the largest
family of Diptera. They are often mistaken for mosquitos. They are non-biting, harmless, gentle, and
poor fliers. Most larvae are aquatic and semi-aquatic. Some adults are pollinators.
- Family Simuliidae – Black Flies: Females require blood. Eggs are laid in running water (ex. streams).
Larvae attach to rocks. Black flies are also hated by humans and transmit diseases such as river
blindness. They are small, black in colour, have short legs, and have a humpbacked appearance. They
insert anti-coagulant saliva into bite wounds.
- Family Ceratopogonidae – Biting midges, Punkies, No-see-ums: Females require blood. They are tiny
flies with adults being less than 1/8 inch long. Larvae live in moist habitats. These flies transmit
bluetongue virus to cattle and sheep. Males and females also feed on nectar and are pollinators of the plant that makes chocolate. Theobroma cacao is pollinated by a ceratopogonoid fly and seeds from
the fruits of T. cacao are the source of chocolate.
- All of the