#Agronomics sub-headlines ##| Learn about field pests --- aphids
There are many common pests in the field. For example, grasshoppers, dice, aphids, big green insects and so on. They wreak havoc in the fields and harm crops.
Let's start with an aphid.
Aphids, also known as greasy insects and honey worms, are a class of plant-eating insects that include all members of the Aphid family (also known as Aphididae, scientific name: Aphidoidea). Aphids have been found in a total of about 4400 species in 10 families, most of which belong to the aphid family.
Aphids are also one of the most destructive pests on the planet. About 250 of these are pests that are seriously harmful to agroforestry and horticulture. Aphids vary in size and range in length from one to ten millimeters.
Aphids' natural enemies are ladybirds, aphid-eating flies, parasitic wasps, aphid midge larvae, crab spiders, grasshoppers, and insect pathogenic fungi (containing green zombie fungi).
Aphids are widely distributed worldwide, but are mainly concentrated in temperate regions. In addition, species diversity is much lower in the tropics than in temperate zones. Aphids can migrate remotely, mainly by spreading in the form of winds; for example, lettuce aphids are thought to have spread from New Zealand to Tasmania in this way. And some human activities can also help with the migration of aphids, such as the process of transporting plants attached to aphids.
Aphids – the fastest-breeding insects. Aphids, commonly known as greasy worms or honey worms, belong to the order Hemiptera (formerly homoptera). The 4 to 5 oblique veins of the forewings, the sensory circle born at the junction of the base of the 6th segment of the antennae and the whip is called the "primary sensory circle", and the one born in the remaining segments is called the "secondary sensory circle". Aphids are polymorphic insects, the same species have no wings and wings, winged individuals have one eye, wingless individuals have no single eyes. Winged individuals have 2 pairs of wings, the forewing is large, the hindwing is small, and the forewing has a thick vein formed by the combination of longitudinal veins near the forewing edge, and there is a winged nevi at the end. There is a pair of abdominal tubes on the dorsal side of the 6th ventral segment and a tail piece at the end of the abdomen.
The body length is 1.5 to 4.9 mm, most of which are about 2 mm. Sometimes wax powder, but wax flakes are missing. Antennae 6 segments, a few 5 segments, rare 4 segments, sensory circle-shaped, rarely oval, terminal ends often longer than the base. The eyes are large and small, and there are often prominent 3 small eye surface eye tumors. The beak segment is short blunt to long pointed. The abdomen is larger than the sum of the head and chest. There are often marginal tumors in the segments of the anterior chest and abdomen. The abdominal canal is usually tubular, often larger than wide, thick at the base, tapering toward the ends, sometimes swollen in the middle or end, often with marginal protrusions at the apex, smooth or tiled surfaces or reticulated at the ends, rare with few or more hairs, and rarely with rings or absences of the abdominal canal. The tail is rounded, finger-shaped, sword-shaped, triangular, pentagonal, helmet-shaped to half-moon shaped. The tail plate end is rounded. The epidermis is smooth, reticulated or wrinkled, or a streak consisting of slight spines or granules. The body hair is sharp or the apex is inflated to the head or fan. Winged aphid antennae usually have 6 segments, and the 3rd or 3rd and 4th or 3rd to 5th segments have secondary sensory circles. The midrib of the forewing is usually divided into 3 branches, and a few are divided into 2 branches. The hindwings usually have 2 elbow veins, and rarely the hindwings become smaller and the wing veins degenerate. The wing veins are sometimes black-edged. The body is translucent, mostly green or white.
