228 



SCIENCE. 



[Vol. XIX. No. 481 



The annual report of the trustees, containing an account 

 of the organization and work of the Laboratory, may be 

 obtained from the secretary. 



HOMOPTERA INJURIOUS TO GRASSES. 



Among the many insects that are destructive to the grasses 

 the little leaf-hoppers take a very prominent place, and the 

 writer is of the opinion that, although their work is often or 

 for the most part entirely overlooked, they are really re- 



PIG. 1. 

 Diedrocephala molllpes (Original). 



sponsible for much of the damage accredited to other insects 

 or to drought. Studies carried on during the last few years, 

 and which have been reported in bulletins of the United 

 States Department of Agriculture ' ° and of the Iowa Experi- 

 ment Station, ^■' lead to the opinion that from one-fourth to 

 one-half of the crop is lost regularly as a result of their work, 

 and that a large part of this loss could be saved by the adop- 

 tion of remedial measures. It seems also, at least for blue- 

 grass in Iowa, that the common affection known as "silver- 

 top" is to be charged against these same insidious enemies.^ 

 While there are many different species concerned iu this 

 work, many of which have still to be studied, and repre- 

 senting the families Jassidce, Cercopidce, and Jfulgoridce, 



Deltocephalus Inimi- 

 cus (Original). 



the most numerous, and I think the most destructive, fall in 

 the family Jassidce, and a few of the more common ones 

 may be enumerated here. 



Diedrocephala mollipes is a grass-green species about one- 

 third of an inch in length, and its general form, as well as 

 the larva and pupa are shown in the accompanying figure. 

 It occurs abundantly all over the country, but may be no- 

 ticed more abundantly some seasons than others, and it shows 

 a preference for ground that is moist rather than for very 

 dry localities. 



A quite similar species, Diedrocephala noveboracensis, is 



• Bulletin No. 22, Division of Entomology, United States Department ol Ag- 

 riculture, pp. 20-41. 



^ Bulletin No. 23, Division of Entomology, United States Department of Ag- 

 riculture, pp. 58-59. 



2 Bulletin No. 13, Iowa Experiment Station, pp. 95-101. 



' Bulletin No. 15, Iowa Experiment Station, pp. 25S-26I. 



' Proceedings of tlie Society for Promotion of -Agricultural Science (1890). 



also quite abundant and widely distributed, but seems to oc- 

 cur more especially around the borders of thickets and in 

 grassy woodland. 



Perhaps the most abundant and widely distributed species 

 of all is the Deltocephalus inimicus of Say. Its work ranges 

 all through the season, and it may even be found on warm 

 days in winter. 



The insect is nearly a fourth of an inch in length and of a 

 grayish color, the most distinctive marks being the black 

 dots on head, front portion of thorax, and on the scutellum ; 

 two on each, as shown in the accompanying figure. 



Another species which occurs, at times in immense num- 

 bers, is the Deltocephalus debilis of Uhler. This is smaller 

 than the preceding species, but without a careful examina- 

 tion may be very easily confused with it. It is quite uniform 

 in color, and without the black dots characteristic of that 

 form. Its distribution is probably very wide, though it has 



Deltoceptialus de- 

 bilis Ulil. 

 (Original.) 



not as yet been reported from as many localities as the pre- 

 ceding species. 



Aside from these especially abundant species there are 

 many others belonging to the genus Deltocephalus, which 

 seem to be confined to grasses as their food plant. D. sayi, 

 D. harrisii, D. melsheimerii, and others having been taken 

 in greater or less abundance in sweepings from grass. 



Cicadula exitiosa Uhler was first described as a wheat 

 pest, but it has proven a general grass feeder, and must be 

 enumerated among the species affecting this crop. It is 

 about two-tenths of an inch in length, of a brownish color, 

 and the wings are quite distinctly marked with dark veins. 



Cicadula exitiosa Ubl. 

 (Original.) 



The figure shows its form and the arrangement of the mark- 

 ings of the body. 



Agallia sanguineolenta Prov. is an interesting little spe- 

 cies, often secured in grass and conspicuous in very early 

 spring, as the adults can be seen in great numbers under the- 

 grass or, on warm days, hopping about on the leaves. It 

 has proved, however, to favor clover as its food plant, and 

 probably feeds on grass only during fall, winter, and early 

 spring. It is about one-eighth of an inch in length, quite 

 broad, about half as wide as long, and marked with numer- 



