Immature Stages of Evaniidae
Detailed information on immature stages of Evaniidae is being acquired. However, Clausen (1940) noted that the egg is cylindrical, 1.0 mm. long X 0.25 mm. In the greatest width, slightly curved, and with one end clearly constricted and terminating in a broadly conical structure which bears a minute pedicel.
The 1st instar larva is slightly cylindrical with 13 distinct segments, simple but strongly extruded mandibles, and a complete internal tracheal system, but no spiracles. In this stage, feeding is confined to the contents of the single egg, but following the first molt the neighboring eggs in the capsule are attacked. In its first stage, the larva is thus a true egg parasite, while it becomes an egg predator after the molt. The 2nd instar larva is globular in form but otherwise closely resembles the preceding instar, the distinguishing characters being those of the head. The 3rd and last instar larva is very robust, ca. 2X as long as wide, with the head large and the mandibles still simple. There are no integumentary spines, sensory setae, or sculpturing upon the body. The tracheal system is open, with 9 pairs of spiracles located on the 1st and 3rd thoracic and the 1st 7 abdominal segments. In addition to the usual anterior and posterior commissures, each of the 7 abdominal segments possesses an accessory ventral commissure.