164 INDIRECT BENEFITS DERIVED FROM INSECTS. | 
pierces its wall, however thick, and commits the destroying egg to its 
offspring. Even the clover-weevil is not secure within the legumen of that 
plant ; nor the wire-worm in the earth, from their ichneumonidan foes, 
I have received from the late Mr. Marwick that of the former, and 
Mr, Paul has shown me the destroyer of the latter, which belongs to 
—\Latreille’s genus Proctotrupes. Others arenot more secured by the repulsive 
mature of the substance they inhabit ; for two species at least of Ichneumon* 
‘know how to oviposit it in stercorarious laryae without soiling their wings 
or bodies. ; 
~The ichneumonidan parasites are either external or internal. Thus the 
species above alluded to, which attacks spiders, does not live within their 
bodies, but remains on the outside? ; and the larva of Ophion luteum, 
which adheres by one end to the shell of the bulbiriferous egg that pro- 
duced it, does not enter the caterpillar of Huprepia villica, the moth upon 
which it feeds.§ But the great majority of these animals oyiposit within 
the body of the insect to which they are assigned, from whence, after 
having consumed the interior and become pup, they emerge in their 
perfect state. An idea of the services rendered to us by those Ichneumons 
which prey upon noxious laryz may be formed from the fact, that out of 
thirty individuals of the common cabbage caterpillar (the larve of Pontia 
Brassice) which Reaumur put into a glass to feed, twenty-five were fatally 
pierced by an Ichneumon (Microgaster globatus*). And if we compare the 
myriads of caterpillars that often attack our cabbages and brocoli with the 
small number of butterflies of this species which usually appear, 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 Hymenoptera: 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 Bchinomyia, Nemor@wa, &c.),as well as of Anthrax, and other genera 
depositing their eggs in caterpillars and other larva, often in such great 
| numbers, that from a larya of Sphinw atropos, bred by M. Serville, and 
which had sufficient strength to assume the pupa 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 paradowus, 
which is found in the nests of wasps; those of the genus Sifaris, which are 
found in the nests of wild bees of the genus Anthophora®, and those of 
Brachytarsus seabrosus, which feed on Coccide’, &c. : 
1 Alysia Manducator; and another species allied to Alomyia Debellator, which 1 
haye named A. Stercorator. 
2 De Geer, ii. 863. ‘ 5 Ibid. 851—855. 
4 Reaum. ii, 419. 
® Macquart, Dipteres, ii. 105. Comp. De Geer, i. 196. vi. 14. 24. Reaum. ii. 
440—444, 
6 Ann. Soc. Ent. de France, viii. Bull, xvii. xlvii. Mucb obscurity exists as to 
the economy of these insects, chiefly in consequence of the curious facts observed by 
my friend M. Peechioli of Pisa with regard to his new species Sitaris solieri, de- 
scribed by him in the Ann. Soc. Hint. de France, viii. 5. 27. He always found both 
sexes of this species, even in distant localities, on plants of rosemary; and these 
For note 7 see p. 155. 
