PDF - Wallace Online

70 NATURAL SELECTION inas the British genus Volucella and many of the tropicalBombylii, and most of these are exactly like the particularspecies of bee they prey upon, so that they can enter theirnests unsuspected to deposit their eggs. There are also beesthat mimic bees. The cuckoo bees of the genus Nomada areparasitic on the Andrenidse, and they resemble either waspsor species of Andrena ;and the parasitic humble bees of thegenus Apathus almost exactly resemble the species of humblebees in whose nests they are reared. Mr. Bates informs usthat he found numbers of these " cuckoo " bees and flies onthe Amazon, which all wore the livery of working beespeculiar to the same country.There is a genus of small spiders in the tropics which feedon ants, and they are exactly like ants themselves, which nodoubt gives them more opportunity of seizing their prey and;Mr. Bates found on the Amazon a species of Mantis whichexactly resembled the white ants which it fed upon, as wellas several species of crickets (Scaphura), which resembled ina wonderful manner different sand-wasps of large size, whichare constantly on the search for crickets with which toprovision their nests.Perhaps the most wonderful case of all is the large caterpillarmentioned by Mr. Bates, which startled him byitsclose resemblance to a small snake. The first three segmentsbehind the head were dilatable at the will of the insect, andhad on each side a large black pupillated spot, which resembledthe eye of the reptile. Moreover, it resembled apoisonous viper, not a harmless species of snake, as wasproved by the imitation of keeled scales on the crown producedby the recumbent feet, as the caterpillar threw itself backward !The attitudes of many of the tropical spiders are mostextraordinary and deceptive, but little attention has beenpaid to them. They often mimic other insects, and some,Mr. Bates assures us, are exactly like flower buds, and taketheir station in the axils of leaves, where they remain motionlesswaiting for their prey.Cases of Mimicry among the FertebrataHaving thus shown how varied and extraordinary are themodes in which mimicry occurs among insects, we have now