406 RHYNCHOPHORA. 



by a rapid movement of the abdomen against the elytra, the loudest 

 sound being produced by S. intricatus. 



The Scolyti are very much infested by parasites, and but for this fact 

 their ravages might be much more serious ; these parasites consist in 

 great measure of Hymenoptera of the family Chalcididae ; half-a-dozen 

 species of these were bred by Dr. Chapman, Cheiropachus quadrum 

 being much the most numerous ; he found the larvae of S. rugidosus the 

 most liable to attack, a fact explained by its being notable among the 

 Scolytidas for not taking any pains to hide the entrance to its galleries ; 

 this again is explained by the fact that this species attacks fruit trees 

 the bark of which is often very smooth, and affords no crevices such as 

 those afforded to S. destructor by the elm. 



Miss Ormerod (" Manual of Injurious Insects," p. 184) refers to 

 several methods for preventing or lessening the damage done by 

 S. destructor ; as above remarked, healthy trees often repel the attack of 

 the beetles by pouring sap into the burrows ; a Frenchman, M. Robert, 

 acting upon this principle, adopted the plan of removing the whole of 

 the rough outer bark from elm trees (which can be done conveniently 

 by a scraping-knife shaped like a spokeshave) ; this operation caused a 

 great flow of sap in the inner lining of the bark, and the grubs were 

 found to perish in almost all cases soon after ; the application of coal- 

 tar, whitewash, &c , might be in some cases of service, but only to a 

 limited extent ; the greatest preventive of all, however, is to clear 

 away and burn all the old elm trunks which are left everywhere lying 

 on the ground in our parks and fields and wood -yards with the bark 

 still on ; these in most cases are soon found to be swarming with 

 Kcolytus maggots, which will very soon infest and destroy numbers of 

 neighbouring trees. 



The British species are usually regarded as six in number, but I 

 believe that S. carpini exists in our collections, and have added it 

 doubtfully in the hope that it may be confirmed as indigenous. 



I. Second ventral segment of abdomen without pro- 

 jection on its posterior margin. 

 i. Elytra shining with the dorsal striae very distinct 

 and regular and in no way confused with the 

 punctures of the interstices which are evidently 

 finer. 



1. Sutural region of the elytra with a fine series 

 of punctures behind scutellum ; abdomen of 

 female simple, of male with a strong tubercle 

 on the tbird segment and a transverse raised 

 prominence on the fourth segment; size 



larger S. RATZEBUEGI, Jans. 



2. Sutural region of the elytra thickly punc- 

 tured behind scutellum ; third and fourth 

 segments of abdomen in both sexes furnished 



with a small tubercle S. DESTKTTCTOK, 01. 



(Gaoff'royi, Goeze). 



