29 



it places side by side with, and close to, the preceding one. 

 This operation it continues as long as there remains any sap 

 in the body, it is very soon covered with a number of small 

 globules ; which, coming out of its body one after the other, 

 tend towards the front part, aided in this by the movement of 

 the abdomen. It is all these globules collected together which 

 form a white and extremely fine froth, whose viscosity keeps 

 the air shut up in the globules, and prevents its moisture from 

 easily evaporating. If the sap which the larva has drawn 

 from the plant, is exhausted before it feels itself sufficiently 

 covered with froth, it begins afresh to suck, until it has got 

 a new and sufficient quantity of froth, which it takes care to 

 add to its first stock. My own observation leads me to believe 

 that this frothy exudation is secreted by peculiar organs in 

 the tail of the larvae. This exudation undoubtedly serves to 

 protect them from the heat of the sun ; the soft body of the 

 larvae but for this would soon shrivel up ; it also conceals 

 them from birds, and other insects which would otherwise 

 prey upon them. Notwithstanding the concealment, wasps, 

 however, often get them out and carry them off. It is in the 

 froth that the larvae change into pupae, and do not leave their 

 strange habitation to undergo their final metamorphosis. It 

 is in this vaulted cell that the pupa disengages itself, little by 

 little, from its skin, and in the month of September we find 

 these creatures most abundant. Towards the end of autumn 

 the females become gravid : they are then so heavy that they 

 are scarcely able to fly or jump ; while the males, on the con- 

 trary, make prodigious bounds, springing sometimes two or 

 three yards. How few know that the little broad-headed, 

 brownish, frog-jumping insect now so common on plants is 

 the frog-spittle insect in its perfect state. Many good people 

 class these insects along with the Aphides, as species of the 

 very comprehensive, though most unscientific genus, vulgarly 

 called Blight." 



Mr. H. Janson, who was present as a visitor, exhibited a 

 specimen of Sphinx convohmli, taken on the knocker of a 

 door in Victoria Road, Finsbury Park. 



