044 PHILOSOPHICAL TRANSACTIONS. [anNO iG/l. 



Ohservatioiis ahout that Kind of Wasps called Vespce Ichneumones. 

 By Francis JVilloughby, Esq, N" 76, p. 2279- 



Mr. Lister's opinion is, that the muscae ichneumones lay their eggs in the 

 bodies of caterpillars; which I look upon as true and very ingenious, and must 

 suhscribe to it, though I cannot yet absolutely demonstrate it, as I hoped I 

 should have done before this. These ichneumones have all four wings and an- 

 tennae, like bees; their body hanging to their breasts by a slender ligament, as 

 in wasps; most, if not all, have stings, and are made of a maggot that spins her- 

 self a theca before she turns into a nympha. There is great variety of them ; 

 some breed as bees do, laying an egg, which produces a maggot, which they 

 feed till it comes to its full growth : Others, as we guess, thrust in their eggs 

 into plants, the bodies of living caterpillars, maggots, &c. For it is very sur- 

 prising to observe, that a great caterpillar, instead of being changed into a 

 butterfly, according to the usual course of nature, should produce sometimes 

 one, sometimes two or three, and sometimes a whole swarm of ichneumones. 

 I have observed this anomalous production in a great many sorts of caterpillars, 

 both hairy and smooth ; in several sorts of maggots, and which is most strange, 

 jn one water insect. When there come many of these ichneumon maggots out 

 of the body of the same caterpillar, they weave all their thecas together into one 

 bunch, which is sometimes round, with web about it, just like a bag of spider's 

 eggs; but 1 dare venture to answer Mr. Lister negatively, that none of them 

 feed upon spiders' eggs; but it is the similitude of those thecas, conglobated to- 

 gether, to the eggs of spiders, that has occasioned the conjecture. 



One of the green caterpillars, common in the heaths in the north, went so 

 far on to her natural change, that she made herself up into a large brown theca, 

 almost of the shape of a bottle, which was filled with a swarm of ichneumones. 

 And I have observed in one or two other sorts, that from the very aurelia itself 

 has come an ichneumon; which is very odd, that the caterpillar stung and im- 

 pregnated by the ichneumons, should be yet so far unhurt, and unconcerned, 

 as to make herself a theca, and to be turned into an aurelia. 



I have often seen a large ichneumon dragging a caterpillar in the highway. 

 This year Mr. Ray, in company with a neighbour, observed one hauling a large 

 green caterpillar much larger than herself, which after drawing the length of a 

 perch, she lays down, and then takes out a little pellet of earth, with which 

 she had stopped the mouth of a small hole like a worm-hole; then she goes 

 down into it, and staying a very little, comes up again, and draws the eruca 

 down with her into the hole, and there leaves her; and afterwards not only 



