190 



THE YOUNG NATURALIST. 



COMMON ICHNEUMONS 



By S. D. Baikstow, F.L.S. 

 II. METOPIUS DENTATUS. Pz. 



II.— Nine out of every ten collectors of Lepi- 

 doptera are acquainted with Metopius dentatus, so 

 called, perhaps, because of the Dragon fly 

 toothed conspicuousness of its jaws ; and for 

 this reason that almost every Entomologist 

 ••has reared the larva of Bombyx calluna, the 

 common Oak Eggar moth, and upon this 

 caterpillar Metopius dentatus is parasitic. It is 

 a very noble and commanding looking insect, 

 and well worth depositing in the cabinet of any 

 connoisseur of beauty. The markings are 

 well defined, and arranged with great regu- 

 larity, and prone to little deviation. A good 

 specimen will measure somewhat short of a 

 'complete inch from head extremity to ab- 

 dominal termination. The antennae (or horns) 

 are over half an inch long, whilst the distance 

 across from wing tip to wing tip is con- 

 siderablv more than an inch. The antennas 

 are black on the top, brownish yellow 

 underneath. Face, yellow, with black 

 markings; forelegs, yellow;; hinder ones, 

 yellow, and black ; thorax, black, with yellow 

 markings. The dorsal (top) segments of ab- 

 domen are black, with six yellow bands 

 •across, and the ventral (underneath) segments 

 of abdomen are black, with thick contracted 

 yellow streaks ; wings, brownish, with the 

 stigma darker brown, but not dense. May I 

 observe here that it is positively impossible to 

 avoid " terms" altogether. In order to assist 

 my readers with a little knowledge of these, 

 when I have dispensed with " common ichneu- 

 mons" I intend to give a few drawings, 



descriptive of the anatomy and form of 

 I Hymenopterous insects, which will doubtless 

 be serviceable to commencing Ichneumonolo- 

 gists. The difficulty in the way of beginners 

 I have myself had to combat, and this fully 

 explained will form a fair index to the ex- 

 periences of others. Now we are close upon 

 the eve of summer months when grubs will 

 be gorging themselves preparatory to the final 

 metamorphosis, and final pleasures of insect 

 life, and we must get all the caterpillars we 

 can, in order to breed them out "for their 

 parasites' sake." And to do this effectively 

 we must have a pupa cage divided into com- 

 partments, each compartment to contain 

 separate and individual larvae, with their 

 j names correctly attached. By this means 

 j whenever a parasite appears, by looking for 

 I the excavated cocoon ■■' from whence it came," 

 j we can then form a list of the parasites and 

 J their victims. In a large chrysalis cage, 

 ! where insects are constantly emerging it is 

 J out of all reason to suppose that we are able 

 ' to discern which of the many empty car- 

 I casses contained our ichneumon. I am 

 j sure this hint is sufficiently feasible, and 

 i necessary to carry weight. To return, the 

 J (female) dentatus is provided with a short, 

 ; sharp, incisor or sting (aculeus), very dif- 

 . ferently shaped to that of P. instigator, but it 

 j is admirably adapted for what it is required. 

 ; I am not as yet aware whether it is parasitic 

 j upon any other larva besides that of B. callune&, 

 \ and as the latter is within the reach of every 

 : collector we have plenty of scope wherewith 

 I to carry on business. The caterpillars will 

 ! soon be in full force, so that we may reason- 

 I ably expect very shortly to hear from our 

 j young naturalists. The genus Metopius was 

 i arranged by Panzer, and is quite a distinct 

 | order, and easily recognised. We have only i 

 j four British species recorded up to this time, 

 ! but observation will doubtless be the medium j. 

 I of results, and of rendering additional ones. J 

 Iai setting dentatus for the cabinet care must j 

 ; be taken to place it in reverse attitudes, s<M 

 \ that we can inspect the underneath part as Ij 



