Common Bristletails

Immature stages: Similar to adult stage.

Habits: Most species occur in leaf litter, under bark and stones, or in debris; some species may be found in buildings. Importance: A few sometimes are pests in houses. Classification: Two suborders, Ectognatha and Entognatha, differing in the number of terminal abdominal appendages and the segmentation of the tarsi. Many authors give these groups order rank, the Thysanura including only the Ectognatha and the Entognatha being placed in the order Diplura. No. of species: World, 700; N. America, 50.

Common Bristletails: Suborder Ectognatha

Three tail-like appendages at end of abdomen (cerci and a median caudal filament). Compound eyes usually present. Body generally covered with scales. Tarsi 3- to 5-segmented. Mostly active, fast-running or jumping insects.

SILVERFISH Family Lepismatidae Identification: Compound eyes small and widely separated. Ocelli absent. Tarsi 3- or 4-segmented. Coxae without styli.

The Silverfish, Lepisma saccharina Linn., and Firebrat, Thermobia domestica (Packard), the most commonly encountered members of this group, often are pests in houses and other buildings, where they feed on all sorts of starchy substances. They are 10-12 mm. The Silverfish is silvery, usually occurs in cool damp situations. The Firebrat is brownish, inhabits warm situations around furnaces and steam pipes.

62 THYSANURA AND COLLEMBOLA

NICOLETIIDS Family Nicoletiidae Not illus.

Identification: Similar to Lepismatidae but compound eyes lacking and body sometimes not covered with scales.

Nicoletiids may be elongate or oval: elongate forms lack scales, occur in caves and mammal burrows; oval forms have scales, live in ant and termite nests. All are quite rare but have been found in Florida and Texas.

PRIMITIVE BRISTLETAILS Not illus.

Family Lepidotrichidae Identification: Similar to Lepismatidae but body lacks scales, ocelli are present, and tarsi are 5-segmented.

A single rare species occurs in n. California, under bark and in rotting wood of fallen Douglas fir. Yellowish gray, 12 mm., with antennae and tails quite long.

JUMPING BRISTLETAILS Family Machilidae

Identification: Similar to Lepismatidae but compound eyes large and touching and there are styli on middle and hind coxae. Tarsi 3-segmented.

Machilids are active jumpers usually found in leaf litter, under bark and stones, or among rocks along the seashore. Most are brownish.

Diplurans: Suborder Entognatha

Only 2 appendages (cerci) at end of abdomen. Body without scales. Compound eyes lacking. Tarsi 1-segmented. Slender whitish insects about 6 mm. or less. Usually found in soil and leaf litter, under bark, or under stones and logs.

0 0

Post a comment