228 INDIRECT BENEFITS DERIVED FROM INSECTS. 



gaster globatus'^y And if we compare the myriads of cater- 

 pillars that often attack our cabbages and brocoli with the 

 small number of butterflies of this species which usually ap- 

 pear, we may conjecture that they are commonly destroyed 

 in some such proportion — a circumstance that will lead us 

 thankfully to acknowledge the goodness of Providence, which, 

 by providing such a check, has prevented the utter destruction 

 of the Brassica genus, including some of our most esteemed 

 and useful vegetables. 



The parasites are not wholly confined to the order Hyme- 

 noptera : a considerable number are also found amongst the 

 tribe of flies, many of the species of the Dipterous genera 

 Tachina Meig. ; and those separated from it (as Echinomyia, 

 Nemoroaa, &c.), as well as of Anthrax, and other genera 

 depositing their eggs in caterpillars and other larvae, often 

 in such great numbers, that from a larvae of Sphinx atro- 

 pos, bred by M. Serville, and which had sufiicient strength 

 to assume the puj^a state, not fewer than eighty flies of 

 Senometopia atropivora came out of it. ^ Many beetles also 

 are parasitic in their larva state, as the singular Ripiphorus 

 paradoxus, which is found in the nests of wasps ; those of the 

 genus Sitaris, which are found in the nests of wild bees of 

 the genus Anthophora ^ ; and those of Br achy tarsus scahrosus, 

 which feed on Coccidce'^, &c. 



1 Reaum. ii. 419. 



2 Macquart, Dipteres, ii. 105. Comp. De Geer, i. 196. vi. 14. 24. Reaum. 

 ii. 440—444. 



3 j4nn. Soc. Ent. de France, viii. Brit. xvii. xlvii. Much obscurity exists as 

 to the economy of these insects, chiefly in consequence of the curious facts ob- 

 served by ray friend M. Pecchioli of Pisa with regard to his new species Sitaris 

 soZier/, described by him in the Ann. Soc. Ent. de France, viii. 5. 27. He always 

 found both sexes of this species, even in distant localities, on plants of rosemary ; 

 ■and these plants, when M. Audouin examined them with him near Pisa in 1835, 

 were covered with eggs, which the former recognised as altogether similar to 

 those of Sitaris humeralis, with which he was well acquainted. As the species of 

 Sitaris are known to be found in the nests of different Hymenoptera, and particu- 

 larly in those of a wild bee (Anthophora) on the larvae of which their larvae are 

 probably parasitic, the question occurs, with what view these eggs were placed 

 on the rosemary ? The most plausible supposition perhaps would seem to be 

 that after the eggs are hatched the larvee attach themselves, like the supposed 

 larvae of Meloe ( Pediculus Melittce K, ) to which they are related, to the Anthophorce, 

 frequenting the rosemary for honey, and are thus conveyed into their cells ; but 

 nothing certain can be inferred on this head till the contradictory statements as 

 to these last-named larvae are cleared up ; and it seems as yet almost equally 

 doubtful, (as it is also in the case of the other parasitic coleopterous genera Horiuy 

 Jiipiphorus, and Zonitis,) whether the larvae are parasitic on the larvee of the in- 

 sects in whose cells they are found, or on their stored-up food. 



4 West wood, Mod. Class, of Ins. i. 332. 



