''Delphastus pusillus'' is a small

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

which preys on all species and stages of

whitefly Whiteflies are Hemipterans that typically feed on the undersides of plant leaves. They comprise the family Aleyrodidae, the only family in the superfamily Aleyrodoidea. More than 1550 species have been described. Description and taxonomy The A ...

, but prefers

eggs Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...

and

nymphs A nymph ( grc, νύμφη, nýmphē, el, script=Latn, nímfi, label=Modern Greek; , ) in ancient Greek folklore is a minor female nature deity. Different from Greek goddesses, nymphs are generally regarded as personifications of nature, are typ ...

. The adults are small ( in), shiny, black beetles. Newly emerged adults are pale-brown to almost white. They eventually turn black with a brown head. The eggs are 0.2 mm long, clear and twice as long as they are wide. The elongate larvae are pale yellow.

Life cycle

Female beetles live for about 2 months, during which time they lay 3 to 4 eggs per day; male beetles live for 1½ months. The females generally lay their eggs within clusters of

eggs, which makes it easier for the young larvae to find a food source. Each instar lasts 1½–3 days. ''D. pusillus'' pupates on lower leaves, in

leaf litter Plant litter (also leaf litter, tree litter, soil litter, litterfall or duff) is dead plant material (such as leaves, bark, needles, twigs, and cladodes) that have fallen to the ground. This detritus or dead organic material and its constituent ...

, or in other protected locations, often in groups. The

pupa A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their ...

l stage lasts approximately 6 days. Development from egg to adult takes approximately 3 weeks at 80–85 °F.

Use in biocontrol

Both larvae and adults are active

predator 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 th ...

s that can consume numerous eggs or nymphs each day. An adult ''Delphastus'' takes no longer than half a minute to handle a whitefly egg, and devours up to 160 eggs or 12 large nymphs daily. A larva consumes 1000 whitefly eggs (less if it also eats whitefly nymphs) during its entire development. Adults and larvae feed by piercing the insect with their mouthparts and alternately sucking and regurgitating the internal contents to digest and consume it. Adult females feed more on eggs and first

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 ...

s than on later stages. They are strong fliers that will migrate to areas that contain high densities of whiteflies. ''D. pusillus'' is most effective at high whitefly densities. Since adult female beetles must feed on over 200 eggs per day in order to reproduce, it may be of limited benefit in greenhouses where

populations are low. Both adult and larval beetles avoid feeding on whitefly nymphs

parasitised Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

wasp A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder. Th ...

s such as ''

Encarsia formosa ''Encarsia formosa'' is a species of chalcidoid wasp and a well known parasitoid of greenhouse whitefly, one of the first to be used commercially for biological pest control, from the 1920s. They can use at least 15 species of whitefly as a ho ...

'' and '' Eretmocerus eremicus'' when the wasps are in later stages of development.

Sources

Coccinellidae Biological pest control beetles Insects used as insect pest control agents Beetles described in 1852 {{Coccinellidae-stub