The Origin of the Markings of Caterpillars. 291 



more common than defensive weapons. Thus, 

 the caterpillars of the Noctuce belonging to the 

 genus Catocala and its allies, feed only at night on 

 the green leaves of various forest-trees ; by day 

 they rest in crevices of the bark on the tree trunk, 

 which they resemble so perfectly in the colour of 

 their peculiar glossy dull grey or brownish skin 

 beset with small humps, that only sharp eyes can 



of the larger ants. ... At less than two inches behind the larva, 

 on the stem, was a large ichneumon-fly, watching its chance to 

 thrust its ovipositor into the larva. I bent down the stem, and 

 held it horizontally before me, without alarming either of the 

 parties. The fly crawled a little nearer and rested, and again 

 nearer, the ant making no sign. At length, after several 

 advances, the fly turned its abdomen under and forward, thrust 

 out its ovipositor, and strained itself to the utmost to reach 

 its prey. The sting was just about to touch the extreme end 

 of the larva, when the ant made a dash at the fly, which flew 

 away, and so long as I watched at least five minutes 

 did not return. The larva had been quiet all this time, its 

 tubes out of sight, and head buried in a flower-bud, but the 

 moment the ant rushed and the fly fled, it seemed to become 

 aware of the danger, and thrashed about the end of its body 

 repeatedly in great alarm. But the tubes were not protruded, 

 as I was clearly able to see with my lens. The ant saved the 

 larva, and it is probable that ichneumons would in no case get 

 an opportunity to sting so long as such vigilant guards were 

 about. It strikes me that the larvae know their protectors, 

 and are able and willing to reward them. The advantage is 

 mutual, and the association is friendly always." Those who 

 are familiar with Mr. Belt's description of the standing armies 

 of ants kept by the "bull's-horn thorn" ("Naturalist in 

 Nicaragua," pp. 218 222) and by certain Cecropice and Mela- 

 stomtz, will be struck with the analogy between these and the 

 foregoing case. R.M.] 



U 2 



