Contents > Butterflies > Resident > Blues > Long-tailed Blue
Distribution & Status
Common throughout its range. It is known to be a migratory species, so the native population possibly has a boost with migrants from Australia.
Scientific Classification More info
Pea Blue and Pea-pod Argus (Aust)Description
The Long-tailed Blue was first observed in New Zealand on Waiheke Island in November 1965. It is self-introduced, so is considered native. It is one of the commonest blues in the world, as it is found in Europe, Africa, Asia, Australia and islands of the Pacific, including Hawaii. Somehow it has got on biosecurity's non-actionable pest list (5/12/97) (page 12). This is strange considering it should be viewed as a good biological control agent for Gorse (Ulex spp) which is certainly a invasive plant in New Zealand. It can be easily confused with the Common Blue at first glance.Ovum In English
Laid individually usually on unopened flower buds, but sometimes on open flowers. The colour is initially pale greenish-grey, but this turns to a blue-white after a few days. It has a round shape with a flattened top and bottom with short spines on the side. The top is slightly depressed with a dark central area. They hatch in about 7 days.Larvae In English
After hatching, they are a pale yellow colour, but when they start eating this soon changes between a green and pink-brown depending on the foodplant. In the early instars the head is large, exposed and black in colour. But the head doesn't grow at the same speed as the body, so appears to become smaller in size and becomes hidden beneath the body as the larva grows. Older larva also change appearance to a smooth brown-yellow head and the body becomes covered in minute brown spots and dark longitudinal stripe. They have 4 instars and live about 3-4 weeks. Freshly emerged larvae will bore into flower buds to eat the inner parts of the flower buds of the foodplant. When they grow, they will also eat the immature soft seeds within developing seed pods. Their presence can be spotted by the holes in flower buds and seed pods they leave when boring into them. If the larvae runs out of food, then they can pupate successfully, resulting in smaller imagos. Others can become cannibalistic and eat smaller larvae, especially those that are moulting including those that are going into pupation. (This cannibalistic trait is something that many of the Lycaenidae species have). They have been known to have Ants attend to them, but this relationship is yet to be completely understood in New Zealand, however in Australia they are attended by species of Sugar-Ant. Larvae of the Common Blue are often found on the same foodplant, however the Common Blue eat the leaves and flower petals so do not provide competition for food. Grows up to 13-16mm when fully grown.Pupa In English
Variable in colouration from green-brown through pink-brown to brown with darker brown/black markings which are most predominant on the thorax. It is mainly smooth with rounded ends and has a few bristles near the head. It is weakly attached by a girdle to a cocoon amongst leaves and other debris near to the base of the foodplant. They will sometimes pupate inside a seed pod if there is enough room, however they have to stay until the pod bursts or falls to the ground. This causes the adult to start emerging since it can then escape from the seed pod. This wait can be anywhere from 2 weeks to a year, even from the same brood! The pupa is about 8-10mm long.Imago In English
The imago has a 20-36mm wingspan, the average being 28-30mm. Like most Blue Butterflies, the females have only a small amount of blue colouring near the centre of the upperwings, whereas the males have mainly blue upperwings, apart from the brown edges. There is supposed to be a sexual dimorphism on the underside markings of the wings, but I find it very hard to tell them apart this way. The tails (with 2 spots at the base) are rumoured to help in its self-preservation as they could be taken as antennae. They have a rapid jerky flight usually more than 1 metre above the ground. The females will generally stay close to the foodplant, whereas the males will travel further afield. Males are very territorial and will chase off other males who come too close. On settling, they sometimes rub their hind wings up and down, especially if there is another Long-tailed Blue around (the pictured male was doing this when I took the photo, so he looks lob-sided). They normally rest with their wings closed or partially open.Habitat
Open country and gardens where foodplants grow.Food Plants
Broom (Cytisus spp), Peas (Pisum sativum), Sweet Pea (Lathyrus odoratus), Broad Bean (Vicia faba), Gorse (Ulex spp), Lupin (Lupinus spp), Tree Lucerne (Chamaecytisus palmensis) and Rattlepod family (Crotalaria spp).Lifecycle
Note: this is a guide only based on Australian populations and general flight times of imagos. New Zealand records show all stages can be found all year round. A lot more research needs to be done to improve accuracy.
The Long-tailed Blue is a species of Butterfly that still needs further study.
Unanswered questions are;
- Are there any distinct generations in New Zealand?
- How many generations do they have in New Zealand?
- Do they prefer to spend winter as pupae here like they do in cooler climates in Australia?
Please contact nzButterfly.info if you can answer any of the above questions.