The Mosquito/Copepod Kit
  A resource for Florida teachers and students.

The Mosquito Life Cycle

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Mosquitoes undergo complete metamorphosis. As opposed to other animals, where the immatures live in the same habitat as the adult and share the same resources, in insects with complete metamorphosis the immature stages are adapted to a completely different life style than the adults and develop in different habitats.

After hatching from the eggs, the mosquito larva undergoes a series of growth stages with continuous feeding that eventually will transform the insect from a swimming aquatic form to a flying terrestrial one. Because the larvae are covered in a hard protective skin called the cuticle, they must undergo a series of molts in order to grow. Essentially, the larvae are enclosed in a hard inflexible box that must be shed if growth is to occur. However this hard exoskeleton, is absolutely essential for larval survival, so it can't just be discarded. To deal with this problem, mosquito larvae grow a new exoskeleton under the old one. This new exoskeleton is soft and flexible at first, thus allowing the larvae to grow. When ready to molt, the larvae then shed the old exoskeleton and the new one hardens when exposed to protect the larvae's internal organs. Mosquito larvae undergo four such molts. The stages between molts are called instars and are numbered from I to IV.

After the fourth instar, the development of the future mosquito adult is about to start. The process involves the breakdown of the larval organs (mouth parts, musculature, digestive system, etc.) and their replacement with the adult ones. During this process, the mosquito takes a new shape; the pupae. The pupa can be considered to be a sealed chamber, where the adult organs are formed at the expense of the larval tissues. The pupa does not feed or eliminate waste products. Its only contact with the outside is through breathing tubes located on the thorax. After 3 or 4 days, the adult mosquito emerge from the pupa, and after a period of rest, unfold its wings and flies away.

In addition to flies, other insects with complete metamorphosis include beetles, bees, wasps, fleas, lacewings, butterflies, and others.

ACTIVITY: Compare mosquito metamorphosis with that of butterflies. Butterfly kits are available at many locations including:

http://www.butterfly-gifts.com/live-butterfly-kits.html
http://www.earthsbirthday.org/butterflies/activitykit/contents.html

The Copepod Life Cycle

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Copepod eggs hatch into nauplius larvae and the life cycle typically includes 6 naupliar stages and 6 COPEPODITE stages, the last of which is the adult stage. There are marked changes between the last nauplius and the first copepodite stage. Development times from egg to adult are typically in the order of 1 to 6 weeks, but may take several months, and the lifespan of adults may be from one to several months. Developmental times are significantly affected by temperature and food.

During the naupliar stages, the copepod appears unsegmented and with few appendages. First nauplius has 3 appendages. Successive stages feed, moult, grow, and acquire more appendages. After the 6th naupliar stage, important morphological changes occur. The copepod becomes more elongated, segmentation becomes apparent, and the resulting copepodite resembles more or less the adult copepod in general shape. Five copepodite stages occur during which more appendages and body segments develop. The sixth and final copepodite stage results in an adult.