14 



have seen specimens of this or some other species so closely allied 

 to it as to be indistinguishable to the naked eye, when confined in 

 bottles, carrying around the victims which they had impaled upon 

 their piercing mouth parts, apparently being engaged in sucking 

 the juices from the bodies. 



Food Plants. 



This minute pest attacks a number of species of grass ; but by 

 far the greatest damage is done to June grass (Poa pratensis) 

 (Plate I., figs. 5 and 6), few fields of this escaping more or less 

 serious injury. After the first of July, by which time June grass 

 has usually matured, the insect changes to some later species, as 

 timothy {Phleum praiense) , when this is present. They maybe 

 found in abundance upon barn-yard grass (Panicum crus-galU) 

 from midsummer till late in the fall. About the middle of July, 

 1898, I found them quite common upon a field of young corn 

 which was nearly surrounded by grass land, but later in the season 

 they could not be found upon corn. Many other grasses show 

 unmistakable traces of the work of thrips by their whitened heads, 

 and a list of these, with the percentage of " silver-top," estimated 

 on June 29, 1898, is given below ; but I cannot positively connect 

 this species with all the injury. 



The percentages given were obtained by counting the injured 

 and uninjured heads upon a small area on which the damage ap- 

 peared to be of average severity. Slight traces of " silver top " 

 are indicated by a dash in the column of percentage. 



Poa seroiina, 

 Poa nemoralis, 

 Poa compressa, 

 Poa araclmifera, 

 Poa Fletcheri, 

 Poa aqicatica, 

 Poa j)ralensis, 

 Poa Irivialis, 

 Poa cassia, . 

 Agrostis alba, 

 Agroslis canina, 

 Agrostis slolonifera, 

 Agrostis vulgaris, 

 Festuca Olcoll, 

 Festuca heteroj)hylla, 

 Fesluca pratensis. 



Per Cent. 

 30 



80 

 40 

 20 

 10 

 35 

 75 

 10 

 10 

 30 

 20 

 25 

 25 

 20 

 35 



Festuca elatior, . 

 Festuca ovina, . . .95 

 Festtcca chiriicscoln, . . 95 

 Fesluca tenuifolia, . . 40 

 Festuca rubra, . . .20 

 Panicuin crus-galli. 

 Panicuni sangtiinale, . 

 Phleum j^ratoise, . 

 Elyinus striatus, . 

 Elijmus virginicus, 

 Bromus erectus, . 

 Bronius inermis, . 

 Avena flavesce?is-vera, 

 Agropyrum caniiium, . 

 Arrhenatherum avenaceum, - 

 Lolium pere7i7ie, ... - 



