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Signs of Spring

By Adie Leng for Guardian September 1st 2005

It is special to see one colourful, graceful butterfly flying close by and very special seeing dozens of Monarch butterflies chasing each other or resting on a large tree near the Marriner Reserve. One pair mating in the grass was quite oblivious to the many feet and dogs passing near them.

The Monarch butterflies swarm together to rest over winter on trees that provide nectar and protect them from wind and frost. The Monarch was first recorded in New Zealand in 1873 when the garden Swan plant became more readily available. It is the preferred food for the larvae or caterpillars, which can get sick with alternative food sources.

The adults lay the eggs on this plant then 5-10 days later they hatch into striped caterpillars to rapidly develop over 14 – 21 days before they leave their food plant and go quite some distance to make their pupa or chrysalis. Nine to 21 days later, depending on the temperature, they will mature into butterflies. The adult life expectancy averages 60-70 days for active Monarchs and about 6 months for over-wintering individuals. Now native in New Zealand, they are common in Australia (known as the Wanderer), North and South America, Asia and parts of Europe. Their long distance migrations from southern Canada to California and Mexico are impressive. 

We also have a rather beautiful endemic butterfly, the adult Red Admiral, kakahukura, (Vanessa gonerilla gonerilla) which is a rarer sight. Last autumn I saw one in Palmerston North, almost in a panic, trying to find the right plant to lay its eggs so that its larvae could grow before it died.

The adults are long lived and survive on leaking sap from trees such as Pittosporum and Hebe especially in the autumn and blooms of Buddleia during the summer months but their larvae depend on the New Zealand stinging nettle or ongaonga, (Urtica ferox and Urtica incise) although they can also feed on exotic nettles. Ongaonga is nasty to touch so it is not usually grown in our gardens. Thankfully some do just for the Red Admiral to survive. Our obsession with removing weeds reduces their food sources but the major threat is from parasitic wasp larvae, which eat the larvae of the Red Admiral, when they take over this butterfly’s chrysalis to pupate. To enjoy these butterflies we need to encourage the plants they require although the Buddleia is now a plant pest.

For more information check out this link on NZ Butterflies

Autumnal Equinox

The science and significance of the autumnal equinox

Adapted from http://www.infoplease.com/spot/equinox1.html ________________________________________

 The autumnal equinox is a sure sign of autumn or fall.
In the language of science, an equinox is either of two points on the celestial sphere where the ecliptic and the celestial equator intersect. For the rest of us, it's one of two times a year when the sun crosses the equator, and the day and night are of equal length.

At the autumnal equinox (March 21, 2005, 6:23 P.M. EDT), the sun appears to cross the celestial equator, from north to south; this marks the beginning of autumn in the Northern Hemisphere.

The vernal equinox, also known as “the first point of Aries,” is the point at which the sun appears to cross the celestial equator from south to north. This occurs about September 22, marking the beginning of spring in the Southern Hemisphere.

On the date of either equinox, the sun is above the equator and night and day are of equal length (12 hours each); the word equinox is often used to refer to either of these dates.

The equinoxes are not fixed points on the celestial sphere but move westward along the ecliptic, passing through all the constellations of the zodiac in 26,000 years. This motion is called the precession of the equinoxes. The vernal equinox is a reference point in the equatorial coordinate system.