60 



Figure No. 46. Figure No. 47. 



golden eyes (hence the name Chrysopa). It is seen flying lazily around 

 infected trees or plants. 



The larva of the Chrysopa is known to devour fruit and vegetables, 

 but this is an exception, it being a great help in the extermination of aphis, 

 and we recall the fact of their usefulness in South Africa, in preying on the 

 fluted scale, a habit they have sparingly taken to in this State also. 



PODABRUS BEETLES. 



The Podahrus is a genus of beetles, which also have several members 

 which play an important part in keeping the aphidians in check. In 

 Berkeley I have observed them to be very numerous certain seasons; large 

 patches of grain being cleaned of aphis chiefly by their agency. The Poda- 

 hrus is readily known by its yellow feathery antennae, yellow legs and body, 

 and black wing covers. Their flight is slow, and they are readily caught 

 when hovering over the grain. 



SYRPHUS FLIES. 



The appetite of the blind larvae of these insects is something enormous. 

 This spring, when they were found very abundant, feeding upon the plum 

 aphis, I took home at noon two leaves covered with the aphis and with 

 two larvae on each, and left them on a table. In the evening I examined 

 the leaves, and found nothing but empty skins of aphis. The aphis had 

 all been devoured by the syrphus larva?, and these were still hungrj^ for 

 more. In Mr. Hubbard's report of insects injurious to the orange, I find 

 the following; precise and interesting description of the syrphus flies: 



Whenever colonies of aphis are found on the orange there will almost invariablj' be 

 found among them slug-like larvne, which creep about among the plant lice with a leech- 

 like movement, now contracting into an almost globular mass, and again elongating like 

 the joints of a telescope. The minute terminal joint, which constitutes the head of the 

 larvae, is observed to possess a pair of retractile, horny hooks, which work forwards and 

 back, in and out of the mouth, like a rake. As the larva advances with a groping motion, 

 for it is quite blind and eyeless, the outstretched head and neck sweep the surface, and the 

 jaws continue their raking movement until they strike the body of an aphis. Immedi- 

 ately the jaw-hooks grapple their unresisting victim, and soon through the transparent 

 walls of the body the sucking stomach is seen pulsating and drawing through the oesopha- 

 gus, in a continuous stream, the green juices of the plant louse. 



When actively engaged in feeding these larvae continue with the greatest voracity to 

 empty one louse after another, until they have destroyed dozens of them : and their bodies 

 distended with the contained juices become translucent green in color. When lilled to 

 repletion, the larva falls into lethargy, lasting two or three hours; during which the pro- 

 cesses of digestion change the juices of the bodj' to varying shades of brown, and dark 

 masses of fecal matter gradually form in the intestines. The curious changes of color in 

 the semi-transparent larva? are therefore due entirely to the condition of the body con- 

 tents. The full fed individuals usually have a tinge of flesh color, owing to the formation 

 of glandular, creamy masses of fat, which have a roseate hue. When fasting through 

 scarcity of food the fat is absorbed, and the body becomes dark brown and opaque. When 

 feeding, the larva is translucent green; while digesting, the colors change to olive and 

 brown, with distinct nuirkings of reddish brown and black. 



Transformations. — When full fed, the larva attaches itself b.y means of a pair of terminal 

 prop legs, aided by a viscid secretion which it voids, and which, in drying, glues it to the 

 surface of the plant. The body becomes distended and thickened, losing in length what it 

 gains in girth. The skin of the larva is not split or shed, but hardens and forms the 

 puparium, which jirotects the true pupa within. In the puparium the shape of the larva 

 is jirofoundly altered, the l)ody joints are obliterated, the anterior end becomes swollen 

 and broadly rounded, and the'form tapers suddenly behind. 



