KEFORT OF THE ENTOMOLOGIST. 



401 



I have endeavored to find parasites that destroy these worms, but 

 have thus far been foiled in the attempt. 



I have, however, observed three species of Ichneumon flies creeping 

 about upon the plants, which may prove to be parasitic upon it. Two 

 of these are in considerable numbers, as many as fifteen or twenty of 

 each having been observed in a single morning, while but two or three 

 of the third have been seen. 



Besides P. rapce there are occasionally found the larvae of Mamestra 

 picta, J/, chenopodii, and Plutella erxicifcrarum. These do not occur in 

 hurtful numbers, and therefore amount to but a trifle as compared with 

 Pi rapev. 



Hand-picking is not an unprofitable means of ridding a small cab- 

 bage patch of these pests, but when two or more hundreds of the plants 

 are to be gone over, some other means of destroying the worms will 

 necessarily have to be resorted to, as, for instance, pyrethrum or petro- 

 leum. The substances, of course, can be best applied as described in 

 your various recent reports. 



FALSE-CATERPILLAR ON GRASS AND SEDGE. 



(Selandria sp.) * 



During June and the early part of July great numbers of saw-fly 

 larvae were observed to injure the grass on low, wet meadows at 

 various points in the Elkhorn Valley and the valleys of the Loups. 

 These were of two species, and evidently belong to the genus Selandria. 

 In Holt County, where these larva? were observed in the greatest num- 

 bers, the ground was entirely stripped of grass over small areas. 



Although all sorts of grasses were attacked and eaten by the worms, 

 they preferred the various species of Cyperus and Juncus to other 

 varieties. 



Whether these saw-fly larva 1 have been equally numerous heretofore, 

 or whether they have become so recently, I am unable to state. In 

 some localities where these worms appeared in force, it was supposed 

 that the army worm (Leucania unipuncta) had arrived, and therefore 

 much needless apprehension was felt among the settlers. 



No insect enemies were observed to attack them, neither could I 

 learn of* their being devoured by birds or reptiles. I have supposed, 

 though, that the American bittern fed upon them at times, as this bird 

 was frequently started from clumps of grass where the worms were in 

 force, and at other times it was seen picking at something among the 

 grass in which they were. 



I have often found these larvae in moderate numbers during other 

 years while beating for insects along the margins of ponds, but never 

 heretofore were they observed in such great numbers as they have been 

 the present year. 



INJURY TO WILLOWS AND COTTONWOODS. 



For some years the large saw-fly (Cimbex americana) has attracted 

 my attention at various points in Nebraska, by its habit of frequenting 

 hedges of white willow in preference to the various species of the native 



"The larvae forwarded by Mr. Bruner were unfortunately iu alcohol, and the imago, 

 therefore, not reared, and for the present undeterminable.— (J. V. R. 



26 A — '81 



