On the function and development of the sternal spatula in the Cecidomyiidae or gall midges as exemplified by Rhabdophaga saliciperda duf
✍ Scribed by P. Sen
- Publisher
- John Wiley and Sons
- Year
- 1939
- Tongue
- English
- Weight
- 808 KB
- Volume
- 65
- Category
- Article
- ISSN
- 0362-2525
No coin nor oath required. For personal study only.
✦ Synopsis
The sternal spatula has often been the cause of a great deal of disagreement among the workers on Cecidomyiidae, different authors interpreting its homology and function differently. The modern textbooks, consequently, sometimes make confusing statements and Comstock ( '30) ereii goes further to state that its homology and function are unknown. Williston ('08) also made similar statement. Harris ( ' 2 3 ) , working on Miastor, admits his inability to ascertain the function of this structure.
There a r e others who have brought forward some extraordinary theories, each having his own, mithout any cognizance to those that had already existed. Thus, Curtis (1845) thought that this structure was used for locomotion in the Hessian fly, Xayetiola destructor and mistook the anterior bilobed part for two rudimentary legs. While, according to Giard (1893), this structure in the Cecidomyiidae is utilized for leaping movements. He has furnished a n interesting account as to how the l a r r a leaps, which according to him takes place by the larva attaching this organ to certain papillae a t the anal end of the insect and then suddenly releasing the hold. The special advantage in this mechanism, as stated by him, is twofold, firstly it ensures sufficient food supply and secondly it helps in the distribution of the species. Enoch (1891) states that the anchor process is used in reversing the position of the larva whicli lies with the head downward in its burrow in the larval period and it is only later that the insect attains a n upright position within the cocoon prior to miergence. This statement was afterward supported by Marchal (1895). Recently IIetcalfe ( ' 3 3 ) also noted that in Dasyneura leguminicola this structure is used for reversal of position in larval cases.
Another school of thought, headed by Dufour (184.5) considered this as a buccal organ. This author helieved this structure to be the vestige of the retractile mandible as is found in the Muscids. Heeger and Giraud, as referred to by ICieffer ('OO), also held this view; the latter author, however,