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File: <syrph1.ima.htm> [For educational purposes only] Terminology Glossary <Principal Natural
Enemy Groups > <Citations> |
Immature
Stages of Syrphidae
The eggs of the
entomophagous representatives of the Syrphidae are quite similar in form and
appearance, being sub cylindrical, about 1 mm. in length, 1/4th as wide as
long, and slightly arched, with a small conical micropyle. The surface bears a waxy covering which
ranges in color from a glistening white to grayish‑white, with fine
reticulations or longitudinal ridges, most frequently the latter. Heiss (1938) has given an extended account of the classification
of the larvae and pupae of the family, exclusive of the aquatic forms. Characters and keys are given by means of
which the various genera can be distinguished. An outstanding contribution to the biology, morphology, and
anatomy of the larvae of a series of aphidophagous species was presented by
M. L. Bhatia (l939). The reader is
referred to these two papers for a detailed discussion of the characters of
the larvae and pupae, which will be described here only in very general
terms. Please
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The
three larval instars are slug‑like
in general appearance, and those of the entomophagous species are very
similar in form. The larvae are
distinguished from those of other cyclorrhaphous families by two characters:
(1) The posterior respiratory tubes of the second and third instars are
contiguous and partly or completely fused.
(2) Each body segment bears 12 spines, in definite positions. Prolegs are lacking whereas they occur
frequently among the saprophytic species.
The body usually tapers anteriorly, and the body contents arc
distinctly visible through the thin integument. The anterior spiracles are relatively small, whereas the
posterior spiracles of the mature larvae (Fig. 181) are large, contiguous or
nearly so, and often situated at the tip of a sing1e heavy stalk. They bear three slits, which, among the
different species, vary in position and direction with respect to the
spiracular button. Many if not all
representatives of the Syrphidae possess so‑called rectal gills, which
are rarely found extruded in the entomophagous forms. Each gill consists of a pair of simple
finger‑like processes joined at the base. The body color and markings are typical for each species, the former usually
being due not to pigmentation of the integument but to coloring matter
contained in the fat bodies, the arrangement of which also differs among
species. There is likewise a
variation in color of the body fluids, which is often due to the food
consumed by the larvae. The
puparium (Fig. 182) consists of the indurated exuviae of
the 3rd‑instar larva and is of tear‑drop form with the posterior
segments markedly narrowed and the anterior portion broadly rounded. The integumentary spines and processes of
the larvae of the species that bear such ornamentation are shrunken and
distorted. The prothoracic cornicle
of the pupa does not protrude through the puparial wall, and the minute
anterior spiracles of the larva are almost invisible. The operculum is circular and divided
transversely into a dorsal and a ventral piece, which separate upon emergence
of the adult. References: Please refer to <biology.ref.htm> [Additional references may be found at: MELVYL Library] |
