454 



fly) caused considerable damage to pumpkins, marrows, etc. The 

 duration of the stages was as follows : — Egg, from 3 to 4 days ; 

 larva, from 18 to 29 days ; pupa, from 12 to 24 days. The larvae were 

 attacked by a predaceous ant and by a Hymenopteron, parasitic on the 

 pupae. D. brevistyhis, Bez., was found associated with D. bivittatus, 

 but in smaller numbers. The duration of the stages was as follows : 

 larva, 22 days; pupa, from 9 to 11 days. Adults of both species 

 were found on the flowers of Euphorbia sp. A species of Stratyomyiid 

 was reared from marrows infested with D. bivittatus and was probably 

 predaceous on the latter. An arsenical spray recommended for 

 treating fruit trees is prepared according to the formula : — 4 oz. lead 

 arsenate, 3 lb. treacle sugar or 5 pts. unrefined treacle, and from 5 to 8 

 gals, water. Marrows should be protected by cheese-cloth or mosquito- 

 netting placed at a short distance from the fruit. 



OsBORN (H.). Studies of Life Histories of Leaf hoppers of Maine. — 



Maine Agric. Exp. Sta., Orono, Bull. no. 248, March 1916, 

 pp. 53-80 8 figs., 5 plates. [Received 5th September 1916.] 



Leafhoppers are serious pests of grasses and cereal crops in Maine, 

 in that they cause the stunting of affected plants and a reduction in 

 the proportion of proteid and fatty constituents. Cicadula sexnotata, 

 Fall., occurs in Europe and throughout North America. The food- 

 plants are numerous, but in Maine the most serious damage is caused 

 to meadow grasses and oats. Adults are numerous in oat-fields at the 

 end of June and the beginning of July, and deposit eggs in the tissue 

 of the leaf-sheath and leaf-base. Adults in captivity oviposited on 

 oats on the 10th July. The number of eggs laid in any one leaf-sheath 

 or leaf-base is considerable, 37 having been counted in one inch. The 

 average duration of the egg-stage is about seven days. The nymphs 

 upon hatching emerge from the leaf tissue and feed by puncturing the 

 surface. Injury results in the production of whitish areas which 

 gradually become brown and finally black. A poisonous substance is 

 probably secreted while feeding, since there is a tendency for affected 

 leaves to wither and change colour at the tips. Adults appear about 

 20 days after hatching and are probably ready -to begin egg-laying 

 in a week or 10 days. A generation of C. sexnotata probably develops 

 in grass land before 1st July ; adults of the second generation migrate 

 about the middle of August from the oat crop to self-sown oats or 

 other cereals or to grass land. A third generation develops between 

 this date and the beginning of October, and may deposit eggs among 

 the bases of grass plants and pass the winter in this stage. Both 

 nymphs and adults are capable of very active movements ; they drop 

 readily when disturbed and the adults can fly for considerable distances. 

 The species is thus easily distributed to new fields, while control by 

 crop rotation is probably rendered less effective. Adults on young 

 oats can be captured in considerable numbers by the use of a hopper- 

 dozer and the destruction by ploughing of stubble and self-sown crops 

 reduces the numbers of the autumn generation. 



Acocephalus albifrons, L. (timothy crown leafhopper), is apparently 

 restricted to timothy grass and is characterised by the subterranean 

 habit during the nymphal and part of the adult stage. A single 

 generation occurs annually. Eggs deposited in late summer and 



