Types of water garden pool – comparison 2
Caterpillars feed for a large part of their time, consuming an ever increasing amount of food plant as they get rapidly larger. Some species prefer the cover of night to avoid unwanted attention, the Comma, Polygonia c-album, spends most of its time underneath leaves for the same reason. Their excrement, usually called frass, is dropped all over the place in small lumps.
Caterpillars produce a silken thread from organs beside their jaws. This is used for a variety of purposes. It gives the caterpillars a good hold on their food plant and some use it to rest between bouts of feeding
When a caterpillar is fully grown it takes time to wander in search of a suitable pupation site. This stage is sometimes known as the pre-pupa. The larva will let all frass clear its system before pupation.
Different families pupate in different ways. A Nymphalid (left) spins a silken pad and hangs head down using its anal claspers to grip on. A Pierid (right) however spins a pad then attaches itself with head upwards, spinning a silken girdle for support.
A short while after the larva has attached itself the change to a pupa begins. It is thought a hormone is introduced into the system to begin this process. The word chrysalis is derived from a Greek word meaning gold, referring to the color of some Nymphalid pupae, whereas pupa is the scientific word describing this stage of a butterflies life.
Once the caterpillar has transformed into a pupa a remarkable process occurs transforming the contents of the pupa into an adult butterfly. This can take as little as two weeks, but some species over-winter (hibernate) in this stage, only hatching in the warmth of spring. As the pupa is unable to avoid any potential predators they tend to be quite well camouflaged, indeed some are form under the ground.
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