The Family Cordulegastridae are a family of Odonata (dragonflies) from the suborder Anisoptera. They are commonly known as Spiketails. Some vernacular names for the species of this family are biddie and flying adder. The family is distributed world-wide; all eight species in North America belong to the genus Cordulegaster.

The name Cordulegastridae comes from the Greek kordylinus, 'club-shaped' and gaster, belly. The common name spiketails refers to the females' prominent ovipositor.
 
 
 
 

A striking, black insect with yellow rings along the length of the abdomen. Both the thorax and abdomen are black with bright yellow bands, the legs are black with yellow bases and the abdomen is swollen towards the tip. The large green eyes meet in a point at the top of the head. Females can be identified by the presence of a long pointed ovipositor at the tip of the abdomen. As with other dragonflies, the large wings are held outstretched when at rest, not folded back over the body as in damselflies. 

This dragonfly is found in heathland and moorland habitats. They are often seen flying leisurely over mountain streams or a river; they also occasional show up at a pond. They are also typically seen flying over heath land. Their bright yellow and black stripes make them easy to identify, even from a fair distance away. They feed mainly on insects ranging from small prey such as midges to flies, butterflies and even bumble bees. This strikingly-coloured insect is incredibly aerobatic and they sometimes fly very high up into the sky.

The large aquatic larva is hairy, and spends most of its life partially buried in the sediment with just the eyes and tip of the abdomen visible. The short head has prominent eyes, and in common with other dragonfly larvae it is armed with fearsome mouthparts. The larvae inhabit small streams that are typically less than 2m wide and overhung with vegetation. They are not found in still water. 
 
 

Females lay their eggs alone, typically in the morning. The eggs are laid into the sediment of the stream, and the female hovers vertically over the water thrusting her ovipositor downwards into the sediment with a stabbing motion that has been likened to the action of a pneumatic drill. The eggs hatch after a few weeks. 

Larvae live partially buried in the sediment, waiting for suitable prey to pass by, which they then ambush. Their development can take as long as 2-5 years, being slower in colder waters. They undergo several moults during their development, which allows them to grow. These aggressive ambush predators feed on insect larvae, snails, tadpoles and even small fish. 

When fully developed and metamorphosis has taken place, the larva crawls up bankside vegetation and the adult stage emerges, leaving the shed skin of the larval form, known as an exuvia, behind on the vegetation. Emergence usually takes place at night in order to reduce the high risk of predation. Occasionally, larvae may crawl quite a distance away from the water before selecting an emergence site, and may even climb trees. The newly emerged adults, or tenerals do not become sexually mature for around ten days. Like the larvae, the adults are also highly efficient and fearsome predators, feeding on large insects such as damselflies, other dragonflies, wasps, beetles and bumblebees. They are fast, agile and powerful flyers and can be seen on the wing from late May to September.