Tiger Beetle: The Beneficial Garden Beetle
The tiger beetle likes damp habitats. They tend to live on the shores of lakes and streams, sand dunes, salt flats and woodland paths. Although not generally brightly colored and not particularly rare, tiger beetles are probably the most studied of friendly insects.
Although it doesn’t seem to be the case, tiger beetles are colored so that they match the type of area they are living in – almost as though they are camouflaged. Some beetles do have more flamboyant coloring and can run from bright green, orange and black to blue and golden colored. Like many predators, the tiger beetle often relies on speed to capture its prey. They also use their speed to escape if they feel threatened.
Short Life Span
The tiger beetle has a very short life span – only about six weeks – and spends much of that time mating and laying eggs. The tiger beetle larvae take up to four years to mature after hatching from an egg that the female will have laid separately into a mall hole in damp sand or soil. The selection of the egg laying site is very careful because the hatched larva needs to be able to dig a burrow when it hatches.
As soon as the tiger beetle larva hatches it starts to dig a burrow. The burrow can be foot deep or more but the larva spends most of its time at the entrance waiting for victims to walk past. The larva anchors itself to the wall of its burrow and, when it sees suitable prey attacks with lightning speed, capturing the victim in its curved jaws. The victim is dragged into the burrow and injected with digestive enzymes so that it is pre-digested. If there is plenty of food about the larva will be ready to pupate after two years but this can extend to four or five years. When it I ready to pupate the larva plugs the entrance to its burrow and develops a pupa cell. After three or more weeks the adult is ready to emerge. It will stay in the burrow for a further three days to let its exoskeleton harden.
When it is not mating the tiger beetle is a deadly hunter. The beetle will find a good place from which to watch for suitable prey. It will either pounce upon the prey and use its powerful curved mandibles to capture it or will run the prey down if it tries to escape. The prey, ants, other beetles, caterpillars, flies and spiders is consumed where ever it is caught.
The tiger beetle is a beneficial garden insect because it devours a wide range of harmful insects and does no damage itself. Even the pupa burrows help to aerate the soil. The major breeding zones of the tiger beetle are slowly disappearing, especially the sea and lakeside locations so attention might have to be turned to creating undisturbed areas of damp sand. The tiger beetle is one ‘good’ bug we cannot afford to lose.