INSECTS. 



163 



green or reddish brown, also reddish brown -with green 

 abdomen; June to August on rye, barley, oats and 

 several grasses; sucks the axis of the ears, and the 

 flower-stalks; as the (black) eggs remain on the 

 stubble during the winter, it is advisable to plough 

 this deeply in immediately after harvest. The Oat 

 Aphis {Aphis avenm), ^J^ inch, dark green, speckled 

 with white ; on oats and barley, scarcely ever on the 

 ears, but on the leaf-sheaths and the upper sides of the 

 rolled-up leaves. The Hop Aphis {Aphis humuli), -^^ 

 inch, green ; on the under side of the hop leaves, and, 

 when very abundant, on the scales of the fruit. The 

 Cabbage Aphis {Aphis hrassicce), ^ inch, dark green, 

 speckled with grey; from May to September on all 

 kinds of cabbage, and also on other crucifers. 



Seventh Order : Physopoda (Bladder-footed 

 Insects). 



Very minute insects, possessing a characteristic jaw 

 apparatus, with which they pierce the outer skin of 

 leaves or the parts of flowers, and 

 suck their juices. The four small 

 wings have long fringes at their 

 edges; the fore wings are tolerably 

 hard. The ends of the feet do not 

 possess claws, but small bladders or 

 suckers. The metamorphosis is in- 

 complete. In some years, one or 

 other of the species may increase to 

 a very large extent, and these minute 

 insects then fly about in swarms, 

 especially on very hot days; and 

 they also wander about in large 

 flocks. If they settle on the face or 

 hands of human beings, they cause a 

 disagreeable and persistent itching, as they continu- 

 ally walk about. 



The Corn Thrips {Thrips cerealium), ^^ inch. Dark 



Fio. 109 Com Thrips 



i^Thrips cerealium). 



