In Manitoba, tiger beetle fauna is most abundant and diverse in sandy habitats. These habitats include sand dunes, borrow pits, roadside blow-outs and forest edges. Other tiger beetles are attracted to clay soil or salt flats and some prefer living near wetlands.
Markings on the elytra (wing covers) are especially useful in identifying species. Colour is also an important feature with some species having more than one colour form. For very similar species, features such as setae (hairs), etc, can be used to separate them. All are endowed with large, bulbous eyes and impressive mandibles. Sizes range from approximately 8mm to 21mm.
Several species emerge early in spring (mid-March to late-April), after having spent the winter in underground burrows they dig in the soil. Some of these include Sandy, Purple, Festive and Oblique-lined. Tiger beetles that pass the winter as adults mate and lay eggs in spring; their progeny emerge in autumn to carry on the cycle. Both adults and larvae overwinter in species that take more than one year to mature, like Big Sand Tiger Beetle. Others, like the rare Ghost Tiger Beetle, and Laurentian, are active only in summer. Their larvae overwinter.
These beetles are mostly dependent on external sources of heat to regulate body temperature, or ectothermic. On sunny, cool mornings, tiger beetles crouch against the substrate to absorb heat. As temperatures rise, they will adopt postures known as stilting (extending legs) or sun-facing (body held as vertically as possible) to limit exposure to the sun. If these activities fail to keep them at optimal temperature, they will seek shelter in a patch of shade, such as behind a grass stem, or dig a shallow burrow in which to spend the hottest hours of the day. Manitoba's tiger beetles are all diurnal.
Their prey, which is caught on the ground after swift pursuit or sometimes by ambush, consists of any insect they can overpower. They aren't above scavenging food from time to time.
Observing tiger beetles can be an absorbing pastime or diversion. Tiger beetles are charismatic insects and a favourite among beetle enthusiasts. Whether you are studying them or making casual observations, the experience is made all the more rewarding if you are in possession of a pair of close-focusing binoculars and/or a camera. If you can catch up to them, tiger beetles make engaging subjects.
photos and article by Deanna Dodgson