ON THE SPECIES OF TELEAS. 341 



one its prey. You see Providence has foreseen that the earth 

 might at any time be desolated, actually unpeopled, by the 

 natural increase of many kinds of insects, and has provided 

 against it. I have calculated that the common tiger moth 

 caterpillar is every year produced in this island in sufficient 

 numbers to eat up every green leaf or blade of grass ; to starve 

 all our sheep, cows and horses, and so to deprive us entirely 

 of either animal or vegetable food. You know this caterpillar 

 eats almost every thing ; well, of all caterpillars this has the 

 most parasites, so many, that not more than one egg out of 

 fifty thousand produces a moth ; thus its voracity and its pro- 

 ductiveness are rendered harmless. I'll be bound you would 

 laugh when I tell you I breed lady-birds on purpose to destroy 

 aphites ; but it is true, and I assure you it answers capitally. 

 You may depend on it the blacks have some natural enemy 

 besides ducks : if not, ducks would do very well, except that 

 the demand for ducks would be greater, I fear, than the supply ; 

 but a farmer, especially if he has water, ought to keep an 

 immensity of ducks, they are always useful, as they eat such 

 lots of slugs and other vermin, and if within a moderate 

 distance of London, always saleable at a paying price. 



Art. XXXII. — On the Species of Teleas, &;c. By Francis 



Walker. 



The upper abdominal segments form an edge to those 

 beneath in this tribe, as in Platygaster, &c. but the Teleadidce 

 possess a more developed structure, their feelers and antennaj 

 generally have more joints, and a nervure runs along the 

 upper border of each wing ; that of the fore wing sends forth a 

 little branch, and is often continued to near the tip ; some of 

 them have an outward likeness to Encyrtus, Mymar, &c. and 

 are parasites of the eggs of other insects ; they have also the 

 faculty of leaping, which the Platygastres have not : Scelio, 

 however, possesses this faculty only in a very small degree, 

 and differs in other respects from the type : Sparasion has the 

 parts of the mouth much more developed, and can hardly be 

 considered to belong to the same tribe; it runs with great swift- 

 ness, but does not leap. 



