Structures and Terminology of Immature Stages

Eggs of bees are described in Sections 4 and 8. They are not rich in external characters, although size varies as described in those sections, and the chorion of some clep-toparasitic bees is variously modified (Sec. 8). Rozen (2003a) and Rozen and Ozbek (2003) have investigated

Figure 11-1. Diagrammatic lateral view of a bee larva.

eggs of numerous, especially parasitic, bees and in addition to characters of the chorion in general, have found interesting differences in the structure of the micropyle.

Larvae, as described in Section 4, are generally soft and grublike and superficially seem rather devoid of differentiating characters. However, as shown by Michener (1953a) and especially by the many works ofJ. G. Rozen, they have numerous characters that, for phylogenetic studies, are well worth investigating because they appear to be independent of the characters of adults usually used in such work. Special features of larvae of various bee taxa (e.g., Allodapini and young larvae of various cleptopara-sites) are described in the accounts of those taxa. What follows here concerns the morphological features and terminology of ordinary larvae, primarily mature larvae or prepupae (see Sec. 4). Most comparative work has been based on prepupae, partly because, as compared with earlier stages, they are larger, tougher, and found more often because they are commonly longer-lived.

Larvae or prepupae of bees are legless and grublike, most of them shaped about as in Figure 11-1, although a

Figure 11-2. Diagrammatic frontal and lateral views of the head of a bee larva.

few are slender and almost wormlike (Emphorini) and others are extremely fat, only about twice as long as broad (predefecating larvae of Holcopasites, Ammobatoidini). Some have very strong tubercles (Panurginae, especially Perditini; also many Allodapini) and some have conspicuous hairs or spicules. Most segments are divided by an intrasegmental line (Fig. 4-2), usually weaker than the in-tersegmental lines, into cephalic and caudal annulets. Spiracles, which have some useful characteristics, can be seen by clearing in a 10-percent aqueous solution of KOH and then examining them with a compound microscope. Longitudinal series of tubercles, if present, may be dorsolateral, ventrolateral, or sometimes ventral; rarely, there are also mid-dorsal or midventral tubercles but usually not in series.

The terminology of the cephalic structures is shown in Figure 11-2. In forms that do not spin cocoons, the labium and maxillae are reduced in size and by partial fusion.

Pupae (Fig. 4-1e) have received little study compared with larvae (see Michener, 1954a; Michener and Scheir-ing, 1976; Rozen, 2000). Because they are short-lived, they are found less often than mature larvae. Also, most of their features are essentially those of the adults and hence of little importance for phylogenetic studies. They do, however, often have large, robust but soft (like the rest of the integument) spines on the legs or body that seem quite different from structures of adults. Even these spines, however, may usually relate directly to adult features, for they seem to be places in which the long hairs of adults can develop. In particular, at the ends of leg segments, long hairs directed apically would have no place to develop were it not for pupal spines.

Early pupae are yellowish white, like larvae, but as they get older the integument of the adult aquires its coloration, which shows clearly through the pupal integument.

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