[ 698 ] 



on the sap of plants, and exude a sweet secretion. Some 

 species produce galls. Psylla isitis which is extensively 

 destructive to indigo in Bengal, is a gall-forming Psyllid. 

 The Psylla cistellata is a small black fly-like insect which 

 attacks young shoots of mango and makes them abortive. 



(3) The Cicads are unable to leap, and they are larger than 

 aphides or psyllids and sometimes very large. The males 

 are provided with conspicuous drum-like appendages to their 

 abdomen. They are black, green, or yellowish in colour and 

 the wings are either transparent or marked with a row of 

 moderate sized black spots on the nervures. The larvae and 

 pupse resemble the imago in general appearance except that 

 the wings are undeveloped. Some large-sized cicads keep 

 up a perpetual chirping in the silence of forests. Although 

 cicads are commonly to be seen feeding on the saps of plants 

 none of them have been described as injurious to crops. 



(4) Membracidae, which we have already spoken something 

 of in p. 696. (5) The Coccidae or scale-insects are often very 

 injurious to cultivated plants and specially to trees and 

 perennials. The males have two wings. The females are wing- 

 less and scale-like in appearance. Eriochiton cajani attacks 

 the arahar. Aspidiotus destructor is destructive to cocoanut 



7 o. APHIDES AND SCALE-INSECTS. 



(a) Ceylonia thesecola (female and male). 



(b) Icerya ^gyptiacum. (c) Aspidiotus flavescens. 



palms. Chionaspis aspidistras is injurious to the areca nut 

 palm. Dactylopius Bromelii, causes the curling disease of 



