Most spider mite infestations are intitally noticed by seeing damage to the leaf where the mites have sucked dry the tissue leaving yellowing and dead spots. The leaf will yellow, wilt and finally fall off. In extreme cases you will see spidermite webbing. At this point it is too late to introduce predators.
First indication of a fungus gnat infestation are the harmless flying adults.
Secondary indication is wilting of the plant as the roots are being eaten away by the fungus gnat larvae under the soil.
Due to the tiny size of young thrips, you will likely first notice a silvery or transparent area with black dots on the leaf surface. They can also cause deformation of shoots and flowers.
Whitefly are usually first noticed as tiny white moths that flutter up when the plants are disturbed. Upon further inspection you will notice discolored patches and sooty mold growing from their secretions. The larva appear as a small scale on the underside of the leaf.
You will never see a Broadmite unless you have a microscope. They announce their presence by making the leaves of the plant curl inward from the edges and become shiny almost waxy looking.
Weevils are double the trouble. They are destructive as adults and larva. The adults look like a long nosed beetle and chew on leaves and new growth. The larvae are a cream colored grub with a brown head and chew on roots and soft plant tissue near the soil surface.
These pest are the larvae of the click beetle. Damage is found as holes chewed into root vegetables, or root damage to plants. Easy to spot in the soil as light tan, shiny skinned "worm"
Most people don`t understand why crows and raccoons are digging up their lawn. They are usually after the large grubs that are feeding on the turf roots.
Seen as cream colored maggots up to 8mm long chewing tunnels in root vegetables including carrots, celery and parsnips. The adults are a shiny black fly 6mm long with a redish head and yellow legs.