128 PKOCEEDIXGS ENTOMOLOGICAL SOCIETY 



had arrived at the same conclusions in regard to many of the other 

 Coleoptera from the same clays. 1 



Dr. Hopkins remarked that, in his opinion, it is not safe to draw 

 conclusions on any evidences of evolution from fossil forms, stating 

 that he believed that as a rule only the highly specialized species 

 were preserved and that the small and less specialized forms from 

 which present species may have evolved, were not preserved. He 

 added that he was glad to have the additional evidence on parallel 

 evolution brought out by Professor Cockerell in his reference to the 

 resemblance of Florissant forms to those of other countries and 

 continents. 



The second paper, ''Efficiency of a Tachinid Parasite, on the 

 Last Instar of Laphygma'' was read by Mr. Walton. 



EFFICIENCY OF A TACHINID PARASITE ON THE LAST INSTAR 



OF LAPHYGMA. 



BY W. R. WALTOX, Bureau of Entomology. 



During the latter part of August, 1912, an infestation of Laphyg- 

 ma frugiperda occurred on the grounds of the Department of Agri- 

 culture at Washington, D. C., in close proximity to the quarters 

 occupied by the Bureau of Entomology. Observations indicated 

 that the larva? were parasitized in a high degree by Tachinid flies. 

 The occasion was therefore grasped as an opportunity for securing 

 data on the relative efficiency of these parasites in the last instar of 

 the caterpillar. It has been remarked by various observers that 

 caterpillars frequently cast off the eggs of Tachihids with the pelli- 

 cle during ecdysis, before they have hatched or at least before the 

 young larvae have been able to gain entrance through body walls 

 of their host. But as the last instar of some caterpillars is of longer 

 duration than the earlier moults, and as in this stage the larva? 

 are, on account of their larger size, method of feeding, etc., more 

 open to the attack of Tachinida?, it seemed possible that oviposition 

 might prove more effective in this instar than in the earlier moults. 



Accordingly efforts were made to secure information on the 

 following points: (1) Effectiveness of parasitism; (2) maximum 

 number of adult Tachinids to issue from one individual of host; 

 (3) what effect if any had the deposition of supernumerary eggs on 



: A. D. Hopkins. Contributions to Canadian Palaeontology, vol. n, 

 pt. ii. Canadian Fossil Insects. Appendix: Work of the prehistoric Scoly- 

 tid, Phloeosinus squalidens Scudd. pp. 91-92., plate XIV.; XV. 



