THE HOP FLEA-BEETLE. 81 



year would tincloubtcdly be a more opportiine lime for getting the younger 

 stages, but our rearing-cage experiments, starting with the beetles in mating, 

 should give us ample material for the study of the younger stages. The scarcity 

 of the larvae at the time when sought is attributed by the writer to the fact 

 that it was too late for the large numbers of spring and too early for those 

 expected to appear about six weeks later, according to reix)rts of previous years. 

 Those few which were obtained are probably late individuals of the last brood. 



Two other kinds of larvjie are taken commonly in the ground, these being wire- 

 worms and carabid larvte. Many of these are very small, just about the size of 

 our flea-beetle larvae, and the wireworms, when first hatched, are of the same 

 white color, but both of these forms of larviis can be readily distinguished from 

 the flea-beetle larvae. The few pup* obtained are undoubtedly those of what 

 we consider the flea-beetle. 



Development. — From all accounts this flea-beetle keeps emerging continuously 

 throughout the season, though there are periods when the beetles occur much 

 more abundantly than at others. Last year Mr. Hulbert stopped using the 

 tarred boards June 1, when practically all of the beetles had disappeared. They 

 did not reappear until the last week in July, when the jarring method was 

 resumed. This year (1908) he continued the use of the tarred boards up to 

 the second week of July, this difference over 1907 being attributed to the cold 

 wet season. According to this, the next lot of beetles may not appear before 

 the last of August of the present year. Beetles have been seen breeding con- 

 tinuously during the past two weeks, though not abundantly, one pair being 

 seen out of seventy-five or one hundred beetles. Beetles are usually present in 

 considerable numbers in the fall, when the hops are mature, and do much direct 

 injury to the product. 



NOTES ON OTHER SPECIES. 



A few remarks in regard to the larval habits of our other American 

 and some European species of Psylliodes ma}" be interesting. The 

 writer has several times observed the beetles of the equally well- 

 known Psylliodes convexior Lee. in numbers on shepherd's purse 

 {Bursa hiirsa-pastoris) in June near the District of Columbia, and 

 it is probable that this is the larval food plant. Until the publica- 

 tion of Mr. Quayle's article ^- there was no record of any of our four 

 species having been reared; hence, the natural conclusion that they 

 were root-feeders. In Europe no less than fort3'-nine species of 

 Psylliodes are recognized in a recently published catalogue,* and the 

 habits of those which have been studied indicate a preference for 

 cruciferous plants, although several are attached to widely differ- 

 ent groups of iDlants. Thus among European species are the hop 

 flea-beetle {Ps. attemmta Koch), the potato flea-beetle {Ps. a finis 

 Payk.), and a species which is mentioned and figured by Taschen- 

 berg^ as the " raps-erdfloh " {Ps. chrysocephala L.). The last is 

 very abundant and has been known for years to attack edible crucif- 

 erous crops. It has been recently treated (190G) by Mr. Geo. 



" Keitter, Catalogus Coleopterorum EuropiB, pp. 572-574, 1906. 



^ I'raktische Insekten-Kunde, I't. II, p. 303, flg. 79. Bremen, 1879. 



