[23]

Augt 1842.

Waterhouse says in one difficult genus two species had been doubted whether distinct, until caterpillars had been examined, when they were at once seen to be different apparently more so than in imago. In two spinxes Sphinxes, which are quite like except in markings wh are very different; the caterpillars are very like, but yet can be distinguished. Caterpillars of Moths butterflies & Sphingidæ almost as readily distinguished as imagos - in the geometric caterpillars much similarity - but imagos differ much in their markings. Question hard to settle. How is it in young birds?

In one of Doubleday letters there are cases of moths very like with unlike caterpillars & I think reverse case