50 



THE PRACTICAL ENTOMOLOGIST. 



coat or not." So now do I send the picture of the 

 true "Thrips" to the vine-growers, and enquire of 

 them — "Judge ye, if this be the image of your foe, 

 or whether you have not confounded one of your 

 best friends with one of your bitterest enemies." 



The true Thrips of Entomologists, of which the 

 annexed highly-magnified figure will give a very 

 good idea — the hair-line showing its real length, 

 and the two wings on the right side being still more 



Color — blackish. 

 highly magnified, and detached from the body to 

 show their hairy fringes — is an exceedingly minute, 

 four-winged, active, blackish insect. In the larva 

 or imperfect state it differs chiefly in having no 

 wings, and in being then of a reddish or purplish 

 color, like the larva of a Chinch-bug, {Micropus Icu- 

 coptcrvs Say.) There are a great many species of 

 them, belonging to different genera of the Thrijis 

 family; but as no one hitherto has investigated and 

 named our common North American species, we may 

 for the present call them all Tlirlps. 



Naturalists hitherto had always supposed, that 

 these Thrips were vegetable-feeders and injurious 

 to plants. In the Proceedings (III, pp. 611 — 612) 

 I suggested "that they are generally, if not uni- 

 versally, insectivorous, and that those that occur on 

 the ears of the wheat, both in the United States 

 and in Europe, are preying there upon the eggs or 

 larvae of the Wheat Midge {Diplosis trilici), and arc 

 conseijuently not the foes, as has been generally 

 imagined, but the friends of the farmer." At the 

 conclusion of this passage I gave several reasons 

 for my belief; and I have since found Thrips prey- 

 ing upon the gall-making larvje of more than twen- 

 ty diiierent galls, growing on different trees and 

 other plants; so that there is now no manner of 

 doubt in my mind, that Thrips is a true Cannibal 

 insect. The importance of this discovery may be 

 seen at once. The larva of a minute flea-beetle 

 (Haiti/a) often grievously infests clover-blossoms, 

 feeding upon and destroying a large portion of the 

 seed. A Thrips occurs also sometimes in large 

 numbers on these same blossoms. Hitherto, firm- 

 ers, when they detected Thrips on their clover, had 

 supposed that a new enemy was invading it. Now, 

 when they see the Thrips there, they may go to 

 bed and sleep comfortably, satisfied that the depre- 

 dations of the real enemy arc about to be checked. 

 And in the same way, whenever in wheat fields in- 

 fested by the larva of the Wheat Midge, (popular- 

 ly known in the East as the "Milk Weevil" and in 

 the West as the "Ked Weevil,") Thrips are disco- 

 vered in the ears of the infested grain, the farmer 



may know that a friend has come to his rescue, and 

 that the Great Author of Nature is saying to the little 

 pest, through the mouth of the minute and almost 

 microscopic insect which He has appointed to do H is 

 work — "Thus farshalt thou go, but no farther, and 

 here shall this grievous Plague of Flies be stayed." 



I may remark here, that I have found a fiew 

 Thrips haunting the leaf-galls, which have so 

 abounded everywhere in I860 on the Clinton 

 grape-vine, and which have been named viti/olise 

 by Dr. Fitch.* There can be little doubt that 

 tliey were preying here upon the minute Barklouse, 

 which produces this leaf-gall. I have also noticed 

 them to be very abundant in the flowers of the 

 Bracted Bindweed, (Calystegia sepium.) As a 

 small plant feeding beetle (the Conotelus ohscurus 

 of Erichson) also occurs in great numbers in the 

 same flowers, it is not improbable that the Thrips 

 may feed upon its larva. 



So much for the true Thrips. Now for a notice 

 of the two very distinct insects, which I guess to 

 have been mistaken for Thrips by the vine-grow- 

 ers. I am sorry that I can only guess in this mat- 

 ter. But it is not I, but Congress that is to blame 

 here. Congress ought to have long ago invested 

 the Practical Entomolochst with plenary pow- 

 er to send for persons and papers, and to commit 

 any body to jail, for contempt of court, that refuses 

 to answer such questions as may be propounded to 

 him. In the present inefficient state of the la^, I 

 ask the vine-growers what on earth they mean by 

 a "Thrips?" " They defy the Great High Court of 

 Science, and contemptuously refuse to answer the 

 question. And yet — will it be believed in future 

 ages ? — }he Court has not even power to fine the 

 recusant witnesses a few thousand dollars, much 

 less imprison them till they come to their senses, 

 and humbly answer the important questions which 

 have been propounded to them. 



The annexed figure represents the Grape-vine 

 Flea-beetle, (^Holtica rha/j/bea,) in its perfect or 

 winged state. As will be noticed, the hind thighs 

 are enlarged, so that the insect can jump quite vi- 

 gorously ; and of course it is to this jumping pro- 

 pensity that the name of " Flea-beetle "refers. The 

 figure is considerably magnified, to exhibit the true 

 shape and structure of the insect, but the annexed 

 hair-line shows its natural length. The larva, 

 (which is not shown in the figure,) 

 light-brown, with numerous rows of 

 black spots, and has six legs in front /hpiv t 

 and a pro-leg or sham leg at its tail. Ex- /ML |V 

 ccpt that it is of course much smaller <-*•*** 

 it is not very unlike the larva of thi 

 New or Colorado Potato Bug, as figur- Color— steel- 

 ed in the Practical Entomologist blue. 

 (Vol II, p. 1:!.) In April this larva 



* According to the great Missouri Vine-grower, Mr. 

 Geo. Husmaiin, this same gall is also found on the Taylor 

 grape-vine. As I have already stated, I also found it iu 

 limilfd numbers on the Delaware grape-vine. It does 

 not appear to occur on any other cultivated variety ; so 

 that Dr. Shimer's aupiehensious that it will eventually 

 prove us destructive to the grape-vine, as the liurklouse 

 13 to the Apple-tree, arc measurably unfounded. (See P. 

 E. II, p. 18.) 



