''Toumeyella parvicornis'' is a soft

scale insect Scale insects are small insects of the order Hemiptera, suborder Sternorrhyncha. Of dramatically variable appearance and extreme sexual dimorphism, they comprise the infraorder Coccomorpha which is considered a more convenient grouping than the ...

in the family

Coccidae The Coccidae are a family of scale insects belonging to the superfamily Coccoidea. They are commonly known as soft scales, wax scales or tortoise scales. The females are flat with elongated oval bodies and a smooth integument which may be cover ...

with a wide host range. It is commonly known as pine tortoise scale because of the characteristic appearance of the mature females, which look like tiny tortoises 4–5mm long.

Description

The adult scale insect is a glossy reddish brown colour. It has an oval dome shape and is about three millimetres in width. The front end is rounded while the rear end has a distinctive groove. Adults retain their legs and antennae but mostly remain sedentary. The nymphs are a flattish oval shape, yellowish green, with six short legs. The nymphs shed their skin three times and each

instar An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or ass ...

is larger and more convex than the previous one.Fredrick, J. M. 1943. Some Preliminary Investigations of the Green Scale, ''Coccus viridis'' (Green), in South Florida. Florida Ent. 26(1): 12-15; 26(2): 25-29.

Biology

Males have not been recorded for this species so the populations are composed entirely of females. A mature female lays whitish oval eggs and keeps them underneath her body to protect them. She usually chooses the underside of a leaf and adult scales may often be seen in a line on both sides of the midrib and beside the lateral

veins Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated b ...

. Eggs hatch in anything between a few minutes and a few hours. The newly hatched crawlers wander off to find somewhere suitable to settle on a leaf or near the tip of a green shoot. Both nymphs and adults suck sap from the phloem of the host plant. When a large number of scale insects are present, their collective feeding causes a yellowing of the leaves which may later fall, a loss of plant vigour and a reduction in crop yield. The scale insects excrete honeydew on which bees, wasps, ants and other insects feed. Sooty mould fungus often grows on the honeydew and this decreases the area of leaf available for

photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...

, spoils the appearance of the plant and reduces the marketability of fruit. It is especially damaging to young trees after transplanting.LePelley, R. H. 1968. ''Coccus viridis'' (Green) - The Green Scale. pp. 353-355. In Pests of Coffee. Longmans, Green & Co., Ltd., London and Harlow. 590 pages.

Hosts

This scale is of North American origin. In 2021 it became a serious invasive species in Italy, doing much damage to the pines of Rome (''Pinus pinea'').

Ants

This scale is often associated with ants which feed on the honeydew excreted and defend the insects from attack by

predators Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill the ...

such as

lady beetles Coccinellidae () is a widespread family (biology), family of small beetles ranging in size from . They are commonly known as ladybugs in North America and ladybirds in Great Britain. Some Entomology, entomologists prefer the names ladybird be ...

References

{{Taxonbar, from=Q10700643 Hemiptera of North America Coccidae Insects described in 1887