Aphids and white flies, Hemiptera (bugs)

Uniramia

--Centipedes

--Hexapoda 1 (insects)

--Hexapoda 2 (insects)

--Hexapoda 3 (insects)

--Identification to order level

--Insect orders

----Lepidoptera (butterflies, moths)

----Ephemeroptera (mayflies)

----Hemiptera (bugs, cicadas)

----Hymenoptera (bees, ants, wasps & saw flies)

------Bumblebees

----Coleoptera (beetles)

----Dictyoptera (mantids, cockroaches)

----Diptera (true flies)

----Neuroptera (lacewings, ant lions)

----Orthoptera (crickets, locusts)

----Thysanura (bristletails, silver fish)

----Strepsiptera (stylops)

----Thysanoptera (thrips)

----Odonata (dragonflies, damselflies)

----Trichoptera (caddis flies)

----Siphonaptera (fleas)

----Isoptera (termites)

----Phasmida (stick & leaf insects)

----Dermaptera (earwigs)

----Anoplura/siphunculata (sucking lice)

----Mallophaga (biting lice, bird lice)

----Psocoptera (book, bark, dust lice)

----Mecoptera (scorpion flies)

----Collembola (springtail)

----Embioptera (web spinners)

----Plecoptera (stone flies)

----Diplura (bristletails)

----Protura

----Zoraptera

Fast facts about Hemiptera (true bugs)

Have piercing mouthparts, called a rostrum which contains 2 pairs of stylets. The outer pair have serrated edges for piercing, the inner pair form a canal for food to pass up and saliva to pass down. The tip pf the rostrum has receptor cells to assess the suitability of the food source.
Mouthparts usually fold under the body like a clasp knife.
Adults usually have two pairs of wings, the front pair may be partially hardened.
The plant feeders can be serious agricultural pests as they can transmit viral diseases.
Divided into two sub-orders; Heteroptera and Homoptera.
Cuckoo spit is made by a Homopteran bug.
Over 82 000 species worldwide, over 7 000 in Europe, 1 650 in British Isles.

Aphids.

There are about 4000 species world wide, but only about 250 of these are serious plant pests. They feed on the phloem sap of plants. This liquid is very sugar-rich, (think of maple syrup), has a high water content, but is low in nitrogen. So the bug must eat large quantities to get sufficient nitrogen. The gut is modified so that the excess water and sugar can quickly pass from foregut to hindgut then rectum, bypassing the midgut (see right which shows the sap feeding hemipteran digestive tract). The midgut is where the nitrogen and the amino acids are absorbed. This means that the excreted liquid is very sweet, and it is sometimes called honeydew. Some aphids can excrete as many as seven droplets of this sugar-rich liquid an hour - that can be as much as 133% of the insect's weight! And some hemipterans consume more than 100 times their body weight per day.

Ants collect or "milk" aphids, but when there are no ants around to collect the honeydew the aphids flick or squirt the droplets away. Sometimes the honeydew is in quantities large

The Hemiptera are divided into 2 sub orders.

Heteroptera	Homoptera
Wings divided into 2 parts, one part being leathery. Includes shield bugs, bedbugs, water striders, pond skaters.	Wings entirely membranous or hardened. Includes cicadas, leafhoppers, froghoppers, aphids. All homoptera are plant feeders.

Hemipteran (aphid) digestive tract showing the passage of sap through the aphid gut

wingless aphid

Rhopalosiphoninus latysiphon - the bulb and potato aphid

enough to be used by man. In the Old Testament the manna given to the Israelites was probably anal excretions of Trabutina mannipara, which feeds on the tamarisk. The Arabs still collect it today, and call it "man". The Australian aborigines also collect honeydew.

Some aphids have wings and others are wingless, see the drawings below.

They are also prodigious breeders. Females can give birth without mating (parthenogenesis). During summer the young are born live, and one female can give birth to numerous females in a day.

On the right is a drawing showing the position of the stylets as it enters the plant cell wall to suck sap.

greenfly, aphid

Rhopalosiphoninus latysiphon - the bulb and potato aphid

On the left is Rhopalosiphoninus latysiphon - the bulb and potato aphid. As its name implies it is commonly found underground - note how its antennae are flexed backwards to ease movement in hte soil.

Whiteflies belong to the Aleyrodidae family.

They look like minute white moths from 1 - 3 mm long. Their wings are covered in a waxy white powder, and their antennae have 7 segments. They suck from the undersides of leaves, and exude a large amount of honeydew. And often it is this sticky honeydew that is the first sign of whitefly that the gardener notices when there is a whitefly infestation. The Cabbage Whitefly, Aleyrodes brassicae, attacks cabbages and related plants. The Greenhouse Whitefly, Trialeurodates vaporariorum, attacks cucumbers, tomatoes and many other plants.