6o 



THE AMERICAN ENTOMOLOGIST. 



^■^cea piirpui-iella Cham, is a leaf-miner of 

 the Locust ; that is, it burrows in the sub- 

 stance of the leaves between the upper and 

 lower cuticles. Its mine is small and placed 

 at the junction of a vein and the midrib, 

 if this is indeed the work of this species, 

 the history of which has not yet been suf- 

 ficiently investigated. There is also a small 

 larva which is sometimes found inhabiting 

 a tube made of " frass " inside the mines of 

 LithocoUctis robiniella and L. ornatella, and 

 it is possible that this may prove to be the 

 larva of A. purpuriella, as to the larval 

 habits of which nothing can be said with 

 certainty except that it feeds on locust 

 leaves. Gclechia pseudacaciella Cham, is 

 another locust-feeding larva, which when 

 very young, may be found under a minute 

 web which extends a little way along the 

 side of the midrib on the under-side of the 

 leaf, and later in life may be found feeding 

 between two leaflets or inside of the mine 

 of L. robiniella, the pupa of which it fre- 

 quently eats. Dr. Packard mentions another 

 larva, that of Depressaria robiniella, as feed- 

 ing on locust leaves, but it is unknown to 

 me. The larva of Xylesthia Clemensella 

 burrows in the dead locust timber, and pos- 

 sibly also in the living wood, and there is a 

 singular larva, the imago or moth of which 

 is unknown, which burrows in locust twigs, 

 eating the pith. Its jaws, head and thor- 

 acic segments are large and nearly black, 

 and its feet are well developed ; the abdo- 

 minal segments are yellow, marked with 

 spots like those many Gclechia larvge, and 

 the larva is about half an inch long. All 

 of the foregoing species, except perhaps the 

 last and Hispa suturalis, belong to the Le- 

 pidopterous family Tincidce. Besides these 

 the moth Xylcutes robinice, and the butterfly 

 Eiidamus tityrus also feed in the larval 

 state on the Locust ; the former boring 

 in the wood, the latter feeding exter- 

 nally on the leaves. Besides the Hispa 

 before mentioned, another beetle, Clytus 

 robinice, feeds on or rather in the Locust in 

 its larval state, burrowing in the wood. 

 There are also some small Homoptera of 

 the genus Etythroneura Fitch, which suck 

 the juices of the leaves ; but possibly the 



Locust may not be their only food-plant ; 

 and there are two species of Diptera {Ceci- 

 dofnyia pseudacacice and Cecidomyia robinice) 

 which feed exclusively on locust leaves in 

 the larval state. The first of these {C. pseud- 

 acacice^ is not very abundant in this local- 

 ity, but C. robinice is quite abundant and no 

 doubt contributes to the destruction of the 

 trees. It feeds externally on the leaves, 

 causing them to curl and turn pale yellow 

 over the affected part ; but the burnt ap- 

 pearance which the trees present is not 

 attributable to them, but to Hispa suturalis, 

 Lithocolletis ornatella, and L. rolmiiella 

 and Gracilaria robiniella. Prof. Haldeman, 

 in the Pennsylvania Farm Journal, VI, men- 

 tions this appearance, and attributes it 

 chiefly to Cecidomyia robinice and Hispa 

 suturalis; but the two species of Litho- 

 colletis and the Gracilaria were probably 

 unknown to him, and their work was attri- 

 buted to the beetle, which has sins enough 

 of its own to answer for in this respect. 



Locust groves are not so numerous in 

 this region now as they were twenty-five 

 years ago, but whether the insects above 

 referred to have had anything to do with 

 their decrease, I do not know. Their depre- 

 dations only began to attract attention some 

 ten or twelve years ago, and they have been 

 on the increase ever since. By the ist of 

 August the groves look as if a fire had 

 swept over them ; and on examining the 

 leaves in many groves almost every leaflet 

 will be found to contain a "mine," as the 

 burrow of the larva is technically called, 

 and many of them will contain three or 

 four ; while the imago or mature insect of 

 Hispa suturalis will be found in great 

 numbers feeding externally on the leaves. 

 The mine of this species is a large blister- 

 like spot of a brown or grayish-brown color, 

 and the larva contained in it is somewhat 

 flattened, and has large jaws as compared 

 with the other leaf-miners found in the 

 same leaves, and it passes the pupa state in 

 the mine. The mine of Lithocolletis orna- 

 tella is a flat, pale yellowish blotch, and the 

 larva up to its fifth stage is whitish, flat, 

 and small ; after that time however it be- 

 comes green and more cylindrical. It leaves 



