Chapter

Characteristics of Dipteran Insects

Murat Helvacı

Abstract

Diptera means two wings (Di: two, pteron: wing). They have complete
metamorphosis and they are holometabolous insects which means there are 4
stages (egg, larvae, pupae and adult). The name of larval stage is “maggot”. Some
of the dipteran insects cause damage in agricultural production. Some are harm-
ful for humans. Dipteran insects have two wings. Hind wings are reduced and
they are called “halteres”. Function of halteres is balancing when the insects fly.
Except mosquitoes, dipteran insects have sponging-sucking mouthparts. Important
examples for dipteran insects are Olive fruit fly and Medfly which cause damages in
agricultural production. OFF is the most destructive pest in olive growing areas and
Mediterranean fruit fly cause damages in fruit production.

Keywords: characteristics, diptera, haltere, holometabola, mouthpart

1. Introduction

Many insects are called flies such as butterflies and dragonflies, but only insects
belonging to the order diptera are known as “true flies.” Dipteran insects (flies and
mosquitoes) are holometabolous insects which means they have complete meta-
morphosis life cycle. Dipteran insects have 4 stages in their life cycle (adult, pupae,
larvae and egg). Name of larval stages of these insects is “maggot”. Adults of this
order are recognized according to wing types. Front wings are developed for flying.
Other pairs of wings are undeveloped and they have balancing function when
insects fly. These type wings give order its name: two (di-), wings (ptera). One pair
of wing provides flying of insects and other pair developed into balancing sturuc-
tures. The name of other pair of wings which provide balancing during flight, called
“halteres”. Except mosquitoes, dipteran insects have sponging-sucking mouthparts.
Mosquitoes and some other have piercing-sucking mouthparts. The Diptera order is
divided into two or three subclasses: Nematocera and Brachycera, the second being
Orthorrhapha and Cyclorrhapha [1]. There are approximately 152.000 identi-
fied species in this order which are distributed about 130 families [2]. Houseflies,
hoverflies, mosquitoes and fruit flies are the most important species which belong
to the diptera order. Houseflies carry diseases such as cholera and dysentery. The fly
cause serious problems by carrying disease organisms onto food. They take disease
organisms from leg hair or eat them and then feed them to other foods. The adults
of hoverflies feed mainly on pollen grains. The larvae of some species eat rotten
plant and animal materials in the soil or in ponds, lakes and streams.
Another species of hoverflies’s larvae are predators and feed on some harmful
insects such as aphids and thrips etc. So, the larvae of these species are important
for biological control as natural enemies.

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The females of mosquitoes suck the blood of human and several animals such as
farm animals and wild animals. Mosquitoes are vector insects and cause the spread
of serious illnesses such as malaria and leishmaniasis etc. [3]. Fruit flies are the most
destructive pests in horticultural growing. For example, Olive fruit fly are the main pest
in growing areas where table and olive oil production are made throughout the world.
General objectives of this chapter is to provide information about the habitats,
feeding patterns and life cycles of insects belonging to the order Diptera, and the
stages in which they exist in their life cycle; However, it is to provide information on
the characteristics of each stage (adult, egg, larva and pupa) in the life cycle of these
insects. In addition, to give information about the role of insects in this order for
human and animal health and agricultural production.

2. Characteristics of Diptera insects

Dipteran order has 125.000 insect species and is one of the biggest order
throughout the world and is highly diverse. Our world score is based on data from
higher than 152.000 known species and higher than 130 identified families and
these data are from the“World Diptera’s Bio Systematic Database” [2]. Diptera order
has the fourth place after the Lepidoptera, Hymenoptera and Coleoptera. Many
species belonging to the order Diptera are found in almost all zoogeographic regions
of the world. These species are well adapted to a broad range of habitats. Except
the depth of oceans, they can live many habitats on earth [1]. Maximum nutrient
and biomass formation occurs in the maggots of Dipteran order, and the adult this
order usually receives the energy which they need to feed their muscles which have
functions for flying. Widely the broad range of insects (flies) looking for food, the
food of those insects includes honey extract or nectar, blood of vertebrate, pollen,
hemolymph of other insects, and another liquefied or liquefied biological resources
which are suspended or dissolved in vomiting fluid or saliva. Few groups of adults
are predators. Other few groups are completely devoid of mouthparts, so they do
not receive food. Therefore, they have short life span. Larval stage of many species,
as they exist, live in water, alive plant tissues and rotten organic matter. Moreover,
they live as parasites or parasitoids of several animals. These larvae need a humid
and wet atmosphere. In addition, the eggs these species hatch in water surfaces and
larval stage occurs on the water surfaces. Maximum larvae live freely, also can be
found in water, sediments, trees, fruits or decaying biological material, while other
larvae are found in the tissues of living beings [2].

3. Life cycle of Diptera insects

Diptera insects are holometabolous (complete metamorphosis) which means that

they have 4 stages in their life cycles (adult, egg, larvae and pupae). Adult females lay
their eggs and the amounts of eggs vary according to species. The females of some
species lay a few eggs, some other lay thousands of them. Generally, females lay their
eggs near the water and lay them as a group or singly.

3.1 Egg

The eggs are laid grouped or individually by adult females, and the females
usually lay their eggs in water and are sometimes attached to materials. Except for
diapause eggs, eggs tend to stand only last for a few days, which are used to prevent
lack of water or unwanted temperatures in the ecosystem [4].

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Mosquitoes which belong to the order of diptera and Culicidae family, lay their
eggs in bunches or can lay singly in or near water (Figure 1). In contrast, some dip-
teran insects such as Olive fruit fly (B. oleae Rossi) (Figure 2), Medfly (C. capitata
Wiedeman) which belong to the Tephritidae family and Spotted wing Drosophila
(D. suzukii Matsumura) which belongs to Drosophilidae family, lay their eggs inside
the developed fruits.
Usually, adult flies lay their eggs, which will pass into the larval stage within a
few hours or days after hatching. Amounts of eggs which are laid by adult females
vary between 1 and 250.However, multiple sequential egg batches can be made.
Females of Medfly lay 300 eggs in her lifetime. Besides, the Green bottle fly (Lucilia
sericata Meigen) lay about 2000 eggs in confinement. However, in a casual environ-
ment where energy and time are beginning to look for suitable areas to lay their
eggs, the total number may be less than 1000 [2].

3.2 Larvae

Larvae of dipteran insects are easily known by the absence of thoracic structures
(legs). This type of larvae is called Apod larvae. Body parts of larvae are usually
fleshy (thorax and abdomen). The whole body of larvae is tubular and long. Larvae
are approximately 2 0r 25 mm, but some species can be reached about 10 cm length.
There are 12 segments in the bodies of larvae and that segmentation pattern is most
common. 3 of them is found in thorax and 9 of them in the abdomen [4]. Some true
midges, commonly seen in anoxic habitats such as blood worms, have an pigment
which has invertebrate form and respiration function. This is called “hemoglobin”
that helps to capture oxygen molecules [4] (Figure 3). After the eggs hatch, the
larvae of the maximum species pass 3 to 4 stages on land or close to the bottom or
above the water surface. For instance, females of Olive fruit fly And Spotted wing
Drosophila lay their eggs inside the developing fruit [5] (Figures 4 and 5). After the
emerging of larvae, they consume the rotten material in which they are laid. They
eat more foods to store energy and nutrients for pupa stage [1]. Larval period is
completed from nearly 2 weeks to several months. Larvae of Diptera insects do not
have wing pads but are found in pupae [4]. Respiration process takes place above the
skin of many larvae of dipteran insects. There are small gills above the skin of some

Figure 1.
Standing water mosquito and eggs.

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The Wonders of Diptera - Characteristics, Diversity, and Significance for the World’s Ecosystems

Figure 2.
Egg of olive fruit fly inside olive fruit.

Figure 3.
Places of respiratory spikes in Diptera larva. (A) Peripneustic, (B) Amphipneustic, (C) Metapneustic,
(D) Apneustic.

taxa. Other larvae of dipteran insects have spikes and they absorb oxygen from
atmosphere by using long or short breathing tubes.

3.3 Pupae

Pupae of dipteran insects have a non-functional mandible (adecticeous). Their

appendages can be independent from their body (externally) or attached to the body
(obtect). Pupae of exarate types are hidden inside the hardened skin (puparium) of
the final stage of larvae [2].
The pupae stage of dipteran insect varies significantly in shape. The pupae of
some flies look like cross shape between larvae and adult, while other pupae shape
of flies are featureless and they have a structure similar to seeds. The first forms
are typical for Nematocera and are defined as having obtect or body-attached

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Figure 4.
Larva of the olive fruit fly.

Figure 5.
Spotted wing drosophila: (A) egg-laying areas and (B) larvae of spotted wing drosophila.

appendages. For example, the pupae of a Crane fly (Tipulidae) have identifiable
head, thorax and abdomen, but covers of antennae, legs and wing pads attach to the
body of pupae. The exterior of the Nematocera pupa can be decorated with spines,
breathing apparatus which are similar to gill or locomotory paddles.
Brachycera and Cyclorrhapha form the pupal stage in a different and more
discreet way. The so-called higher Diptera family produces pupae that are described
as coarctates, meaning “compressed” or “constricted”. These taxa (eg Syrphidae,
Drosophilidae, Muscidae) form a puparium consisting of hardened skin of the late
larval stage [6] (Figure 6). The pupation of some flies occurs in the olive fruit or
under the soil [5]. After the oviposition, the eggs hatch and the larvae feed on the
fleshy part of the fruit, but leaves the fruit when ripe and some continue to appear
inside the fruit. Larvae fall to the ground and pupation takes place in the soil [7].

3.4 Adult

Adults of dipteran insects have segmented body which includes head, thorax and
abdomen parts. They have compound eyes which are found both side of head [1].
The size and shape of compound eyes are highly variable.

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Figure 6.
Female, serrate ovipositor, male with typical black spots, larvae inside the fruit and pupae of Spotted wing
drosophila.

Adults have dark reddish to black color compound eyes. Some families of
dipteran insects have crossbands or spots of different colors such as Tabanidae,
Syrphidae, Tephritidae, Sciomyzidae families [8].
There is small space in front of the head of adult dipterans. The function of this
small space is to help the adults to see wider area when insects fly. Body color of
adults changes from brown to black, orange or yellow, depending on the dipteran
species [1]. For instance, body color of adults of B. oleae is brown and there are
black spots in two sides of thorax and abdomen parts (Figure 7).
Thorax color of Spotted wing Drosophila is pale brown and there are horizontal
black lines in the abdomen. Males have spots on their wings. Adult males of the
D. suzukii are easily recognized a single black spots which are found on the outer
edges of wings. Furthermore, two dark spots (sex comb) are found both of the
forelimbs. Adult female of D. suzukii has a long, sclerotic, serrated ovipositor,
unblemished open wings and comb on their feet [9] (Figures 7 and 8). Adult
females of dipteran insects have ovipositor which is found at the end of abdomen.
Females use this organ to lay their eggs inside the fruit. Females of OFF and Medfly
lay their eggs (oviposition) inside the mature fruits by using their ovipositors.
Length range varies of adults varies according to dipteran species between 1
to 12 mm, but relative huge species are between 25–60 mm [4]. Sensory organ is
found in front of the head of adults which is called antennae. Antennae are filiform

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Figure 7.
General view of fruit fly adults. Euleia heraclei (a), Ceratitis capitata (b), Trupanea amoena (c), Bactrocera
zonata (d), Bactrocera oleae (e), Drosophila suzukii female and serrated egg laying organ (f) and male (g).

Figure 8.
Spotted wing drosophila: (A) the black spots in the wings of male, (B) female, (C) egg laying organ
(ovipositor) of female.

and front wings are developed to fly and hind wings are undeveloped (halteres) to
balance when insects fly and tarsi 5-segmented [2].

4. Conclusion

Dipteran order has 125.000 insect species and is one of the biggest order
throughout the world and is highly diverse. Diptera order has the fourth place after
the Lepidoptera, Hymenoptera and Coleoptera. Houseflies, hoverflies, mosquitoes
and fruit flies are the most important species which belong to the diptera order. Fruit
flies cause destructive damages in agricultural production. Besides, houseflies trans-
mit serious diseases transmits diseases by carrying disease organisms onto food such
as cholera and dysentery. Mainly, adult hoverflies consume pollen grains. Larvae of
some species feed on rotten plant and animal materials in lakes, streams and ponds
or inside the soil. Another species of hoverflies’s larvae are predators and feed on
some harmful insects such as aphids and thrips etc. So, the larvae of these species
are used in the biological control of harmful insects as natural enemies. The females

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The Wonders of Diptera - Characteristics, Diversity, and Significance for the World’s Ecosystems

of mosquitoes have piercing-sucking mouthparts and suck the blood of human,

livestock and animals by using their mouthparts. Mosquitoes are vector insects and
cause the spread of serious illnesses such as malaria and leishmaniasis etc. Many
of the flies which belong to Tephritidae and Drosophilidae families, cause serious
damages in the agricultural production such as Olive fruit fly, Medfly, Peach fruit fly,
Celery fly Spotted wing drosophila. Dipteran insects can be recognized by some fea-
tures such as developed membranous front wings and hind wings are undeveloped
and called “halteres” which have functions as balancing when insects fly. Dipteran
insects have complete metamorphosis (holometabolous) life cycle which means that
there are 4 stages (egg, larvae, pupae, adult). Females of the adults lay their eggs
into the food source or water. Eggs hatch and larvae complete their development.
Pupation occurs under the soil, plant and animal tissues and water. The richness of
the species in this order, the living in different ecological conditions and the mor-
phological differences show people that this order is economically important and
externalizes the diversity of invertebrate creatures in the world. There are insects in
the Diptera order that cause serious problems in human, animal health and agricul-
tural production. It is important to know the life cycles and habitats of these insects.
Accordingly, the issues are followed (life cycle and habitats) to minimize disease
transmission and damage in agricultural production. Another studies which will do
in the future, will be useful in determining the economic effects of diptera insects on
human health and agricultural production.

Conflict of interest

Author has no conflict of interest.

Author details

Murat Helvacı
European University of Lefke, Lefke, TRNC

*Address all correspondence to: mhelvaci@eul.edu.tr

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms
of the Creative Commons Attribution License (http://creativecommons.org/licenses/
by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,
provided the original work is properly cited.

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DOI: http://dx.doi.org/10.5772/intechopen.96448

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