ZOOLOGY AND BOTANY, MIOEOSCOPY, ETC. 537 



become 2 in. long in four or five weeks. The full-grown larva ceases to 

 feed and digs a cavity in the mud in which pupation occurs, the process 

 lasting about a fortnight in summer, but months in winter. The fully 

 formed beetle that creeps out of the burrow is at first very light in 

 colour, and it takes several days before the familiar dark-bronze appear- 

 ance is assumed. The author's reference to the closed mouth during 

 the action of the hollow mandibles is not clear to the recorder. 



Life-history of Psylla isitis.*— A. J. Grove and C. C. Ghosh have 

 investigated the life-history of Psylla isitis Buckton (Psyllopa puncti- 

 pennis Crawford), the cause of the " Psylla " disease of Indigo. Eggs 

 are laid all the year round if suitable food-plants are available, and the 

 whole development may be gone through in fourteen days in hot 

 weather, but may take forty-six in cold weather. The number of broods 

 in a year is from twelve to fourteen. The eggs are laid in almost 

 any part of the plant. Each is attached by a curious protuberance 

 which is thrust into the tissues of the plant. The different larval and 

 nymphal stages are described. At all stages greyish-white globules of 

 fluid consisting of liquid excreta are extruded from the anus, and six 

 different species of ants were found to attend on the Psylla at different 

 stages and to lick up this fluid. Some species of Psyllidae only weaken 

 the plant by sucking its juices, others cause gall-like growths. The 

 species in question causes distortion of the leaves but no galls. Harm 

 is done chiefly by the larva?, but infection of fresh areas is mainly due to 

 adult females. The Indigo " Psylla " is attacked by a parasite in the 

 nymphal stage, and both nymphs and adults are preyed upon by 

 numerous enemies, but nothing has been found to attack the eggs. 



Egg-laying of Trichiosoma.f — T. A. Chapman has observed the 

 whole process of egg-laying in Trichiosoma betuleti (?), and describes the 

 exact action of the " saw " in cutting the leaf of the willow. The 

 insect chooses a spot quite close to the margin of the leaf and rests there 

 with two apical plates of the saw-sheath pressed closely against, but not 

 gripping the leaf. When the saw is first seen to have entered the leaf, 

 the darker, posterior (in the then position) portions of the saw (the 

 supports), advance slowly, steadily, and uniformly together, while the 

 anterior portions, the "saws," are seen to be in rapid motion. The saw 

 is curled right round the end of its support, and goes to and fro rapidly 

 without altering its position. One portion advances as the other retreats, 

 and the cutting is done by the margins of these two pieces. Actual 

 cutting occupied 1 minute 50 seconds, then a rest of 10 seconds inter- 

 vened, and in 15 seconds more the egg was laid, and the saw withdrawn. 

 Eggs laid on April 22, showed on May 1 a rhythmical to and fro move- 

 ment of the larva? within them, and on May 4 the larva? were hatched. 

 The cutting of the saws is really a scissor-like action. Each of the 

 projections of one of the saws, in passing a similar projection of the 

 other, acted with it as a pair of scissors, cutting through the scrap of 



* Mem. Dept. Agric. India, iv. (1914) pp. 329-57 (6 pis.). 

 t Trans. Ent. Soc. London, 1913, pp. 173-84 (7 pis.). 



