Back to: O level Biology NOTES Uganda syllabus
CITRUS BUTTERFLY(Papilio demodocus)
The citrus butterfly is also referred to as lime butterfly because it feeds on lime and citrus.
Classification
Kingdom : Animalia
Phylum : Arthropoda
Class : Insecta
Order : Lepidoptera
Family : Papilionidae
Genus : Papilio
Species : demodocus.
Characteristics of orderLepidoptera
- They are small to large insects with entire covering of powdery scales on their wings. (lepis-scale and ptera-wing)
- Wings are fastened together.
- No anal cerci.
- metamorphosis is complete.
- Sucking proboscis straightened when feeding but coils underneath the head when not actively feeding.
Habitat
Butterflies live in gardens and forests and where they can feed on nectar from flowers. They are active during day.
External features
The butterfly has three body divisions the head, thorax, and abdomen.
The head
- The head bears two large, bulging brown compound eyes.
- There are two simple eyes (ocelli) behind the compound eyes.
- Above eyes is pair of antenna. These are long jointed and lobbed at the ends. They are sense organs for touch and smell.
- The head also bears the mouth part specially adapted for sucking nectar. The sucking part is long, hollow and flexible tube called proboscis. This has a modified pair of maxillae which coils up when not in use.
- The mandibles, the labium and labrum are poorly developed and hardly used.
The thorax
The thorax consists of prothorax, mesothorax and metathorax. These segments are covered by hairs and divisions are not clearly seen.Each thoracic segment bears a pair of jointed walking legs. The mesothorax and Metathorax in addition bear a pair of wings each which are large and membranous.They are veined and covered by colored scales. When the butterfly is flying, the wings are spread out but when at rest, the wings are raised and held vertically above the body.
The abdomen
The abdomen has ten segments and each bears a pair of spiracles. It is hairy and obscures the segmentation.
Butterflies and moths
Butterflies and moths are both members of the Lepidoptera. Although they appear verysimilar, there are differences in their bodies and behaviour.
Differences between a butterfly and a moth
| Butterfly | Moth |
| It is diurnal i.e. active during day time | Nocturnal i.e. active during night |
| Wings are held upright at rest. | Wings are held horizontally at rest. |
| Small body | Fatter body |
| Body brightly colored | The body is dull |
| Antennae are clubbed or knobbed at the tip | Antennae are pointed at the tip and feathery |
| Pupate above the ground | Pupate in cocoons or in the soil |
The life cycle of a butterfly
A butterfly undergoes complete metamorphosis.A female butterfly ready for reproduction produces a peculiar scent that attracts the male for mating.During mating, the male butterfly deposits the sperms in the genital opening of the female. The eggs are then fertilized internally.The eggsare laid singly or small batches on the under surface of young leaves of citrus plant. This protects them from damage by heat of sun or rain. The eggs are tinny, spherical, white or greenish-white in colour.
The eggs hatch into larvae (caterpillars) after about 3days.
The newly hatched caterpillars are small and black. They have powerful mandibles for feeding, first, the egg shell and later young leaves. The young caterpillar has horn-like body with head,thorax, and abdomen. The thoracic segments bear each a pair of true walking legs and abdomen bearing a pair of claspers on the last segment.The caterpillar moults four times in three weeks before changing to a fully mature caterpillar which majorly feed on leaves
The caterpillar then pupates into pupa.
The fully developed caterpillar stops feeding and finds a suitable place usuallyavertical twig to pupate. It spins a silk pad on the twig and attaches its claspers to it. It then spins its thorax and suspends itself in a slanting position with anterior end pointing upwards. The caterpillar then moults for its last time and changes into pupa (chrysalis). The pupa is inactive i.e. it does not feed nor move.During pupa stage-there is internal reorganization of tissues involving the formation of wing, compound eyes, proboscis and reproductive organs. This lasts for about 7-10 days after which the pupa case split along the dorsal region.After about 1 hour while the wings expand and dry, the adult butterfly emerges ready to fly away, feed, mate and lay more eggs.
Economic importance of citrus butterfly
- From the cocoons of butterfly, silk threads are obtained for making silk clothes.
- The larvae spoil the leafy vegetable with fecal drops such as dodo.
- The scales may be respiratory hazards when inhaled.
- The caterpillar stage of a butterfly is significantly destructive on vegetables including crops such as cabbages, maize, millet sorghum etc.
- Some caterpillars feed on insects thus help in destroying insect pests.
- Butterflies can also be used as decorations because of their beautiful colour patterns (ornamental purpose) used in art industry.
- The butterflies also are of much importance to the farmers in pollinating flowers of the crops
Control measures against butterflies
- Apply environmental friendly insecticides
- Use of biological control methods
- By hand picking of the infected leaves and burning or burying them. This destroys the eggs and some leaves.