THE ENTOMOLOGIST 



Vol. XLIL] OCTOBEE, 1909. [No. 557 



SOME POINTS IN THE LIFE-HISTOEY OF ANTHOMYIA 

 SPRETA, Meig. 



By W. J. Lucas, B.A., F.E.S. 



(Plate VI.) 



In the early summer there may not infrequently be seen 

 a curious white fungus which engirdles the culm of certain 

 grasses for nearly an inch of its length (pi. vi, fig. 1). This 

 is parasitic on the grass, causing injury to it by checking its 

 growth above the part affected by the fungus. A glance at the 

 figure shews that the parasite and its host, the grass, bear no little 

 similarity to a miniature bullrush, and this resemblance, we may 

 assume, suggested the name Epichloe typhina, Tul., for the fungus. 



To get rid of this fungus is not an easy matter for the 

 agriculturist, but fortunately he has somewhat of an ally in 

 a small diT[>tei'on, Anthomyia spreta, Meig.* This fly lays its eggs 

 on the surface of the fungus. They are somewhat cylindrical 

 pale bodies, one of which may be seen unhatched on fig. 2a 

 magnified about six times. When it hatches, the egg splits 

 along the side attached to the fungus, and the egg-shell does not 

 fall away, but remains where it was first laid. An egg-shell may 

 be seen at fig. 2& a little above and to the left of the unhatched 

 egg. When they enter the world the little larvsG find beneath them 

 an immediate supply of suitable food, on which they literally make 

 incursions, traces of which may be seen below the egg-shell. 



As the larva (fig. 6a, b) grows, the egg-shell does not properly 

 cover it, and it builds a waxy tunnel with the egg-shell on its 

 surface, and within this it shelters when not making incursions 

 into its food. In consequence of this the egg-shell, which was 

 cylindrical at first, now has its two broken edges separated from 

 one another. The upper surface falls in as it becomes approxi- 

 mately fiat, and then a ridge in the shape of a long ellipse is 

 formed surrounding the depression. This is very well shewn in 

 fig. 4. The traces of the incursions made by the larva to obtain 

 food are also very clear in this figure, and in the preceding one 



* The first aud fairly full account of the life-history of this fly is given 

 by M. le Docteur Giraud in the ' Annales de la Soc. Ent. de France,' 1872, 

 p. 503. 



ENTOM. — OCTOBER, 1909. X 



