150 [July. 



They had, however, a parasitic enemy of quite an unusual kind ; 

 this was a larva of a Syrphus fly, that preyed on the larvae, by 

 hunting and eating them, just as so many Syrphid larvse do with 

 Aphides. I was, of course, somewhat struck by this fact and made 

 various observations and experiments to satisfy myself that it was 

 not a mere accidental occurrence, or that I was not in any way 

 mistaken. I found the SyrpTius eating (sucking ?) the Tortrix larva, 

 I found remains of Tortrix larvae that had been eaten (partially eaten 

 or sucked). I found larvse in a plant disappear, and nothing to show 

 for it but their remains and a larva of Sijrplius. I searched 

 sedulousl}' for any Aphides or Coccids, or other possible prey of the 

 Syrphus, not only on my plants with hyerana larvae, but over many 

 plants at large, but could never detect any, nor could I find larvae of 

 the Syrphus except with H. hyerana. A few Syrphus larvae placed in 

 a box with some larvae of the Tortrix soon managed to catch and 

 demolish the latter. As soon, as by the lashing movement of its head, 

 the Syrphus touched a Tortrix, the latter was captured and unable to 

 escape, a position of affairs of which I was much reminded when, 

 later in the year, I fed some Myrmeleon larvae with caterpillars. 



I found the Syrphus larva in the living tubes of hyerana, but 

 did not learn how they got in, and am unable to say whether their 

 entry is due to some accident, or whether the best defences of the 

 Tortrix are useless against the fly. These Syrphids pupated as soon 

 as full-fed, they began to emerge as imagines April 24th, and had all 

 come out in another week or two. I bred nearly a score. The fly is 

 Xanthandrus comtus, Harris, a species that I learn from Verrall's 

 work on Syrphidce is a rather rare British species, and is held to be 

 seen only in autumn. 



Of course, the climate of Hyeres is so different from ours, that 

 no conclusions can well be drawn from the one to the other. One 

 thing, however, seems so probable that one may almost say it is 

 certain, and that is that the flies that emerge in April and early May 

 do not survive to lay eggs the following February or March on the 

 Asphodels, so that there must be an intermediate brood, one at least, 

 that lives on some other plant, and eats some other insect, aphis, or 

 larva. 



I, reared, after I got home to Reigate, a number of Syrphus larvae 

 from eggs found on Veronica chamcedrys. These larvae throve well on 

 Aphides, amongst which the eggs were found, but also eat larvae, 

 when supplied with them and deprived of Aphides. Several other 

 captured Syrphus were experimented with, and some of them would 



