VII 



BOMBYLIIDAE ACROCERIDAE 



489 



spretus are emptied of their contents by the larvae of Systoechus 

 oreas and Triodites inns. A similar observation has been made 

 in the Troad by Mr. Calvert, who found that the Bomhyliid, 

 Callostoma fascipennis, destroys large quantities of the eggs of 

 Ccdoptenus italicus. Still more recently M. Kiinckel d'Herculais 

 has discovered that the destructive 

 locust Stauronotnx nuifoci-tinns is 

 kept in check in Algeria in a 

 similar manner, as many as 80 

 per cent of the eggs of the locust 

 being thus destroyed in certain 

 localities. He observes that the 

 larva of the fly, after being full 

 fed in the autumn, passes the 

 winter in a state of lethargy- 

 he calls it "hypnody" -in the 

 egg-case of the locust, and he 

 further informs us that in the 



FIG. 233.- 



Africa. 



-Kystropus crudelis. South 

 A, Pupa ; B, imago, ap- 



pendages of the left side removed. 

 (After West wood.) 



case of Anthrax fenestralis, which 

 devours the eggs of the large 

 Ocnerodes, the lethargy may be prolonged for a period of three 

 years. After the pupa is formed it works a way out of the case 

 by means of its armature, and then again becomes for some days 

 immobile before the perfect fly appears. Lepidopterous larvae 

 are also attacked by Bombyliid flies. A species of Systems has 

 been recorded as destroying the larva of Limacodes. Several of 

 the Bombyliids of the genus just mentioned are remarkable for 

 the great resemblance they display to various Hymeiioptera, some 

 of them being very slender flies, like the thin bodied fossorial 

 Hymeiioptera. The difference between the pupa and imago in 

 this case is very remarkable (Fig. 233). 



Fam. 21. Acroceridae or Cyrtidae. Flies, of the average size, 

 of peculiar form, the small head consisting almost entirely of the 

 1'i/i's, and bent down under the humped thorax : wings small, halteres 

 entirely concealed ly the very large horizontal squamae; antennae 

 very diverse. The peculiar shape of these flies is an exaggeration of 

 that we have already noticed in BonibyUus. The mouth in Acro- 

 ceridae is very variable ; there may be a very long, slender proboscis 

 (Acrocera~), or the mouth-parts may be. so atrophied that it is 

 doubtful whether even an orifice exists (Of/codes^). There are but 



