1SG4.] 619 



lines ill those galls, just as Antlionomus KrufrNnfiis Schonh. is inqui- 

 linoiis in the Tenthredinidous "-all S. j)omimi^ and in several other 

 Tenthrediuidous willow-galls, and as the snout-beetles enumerated in 

 this Paper under Coleoptern are inquiliuous in their respective galls. 



INQUILINOTJS CECIDOMYID.E OR GUEST GALL-GNATS. 

 Genus CECIDOMYIA— Subgenus CECIDOMYIA. 



A. The following occurs in prodigious abundance under the scales 

 of the pine-cone like Gall, *S'. strobifokhs 0. S., but not imbedded in 

 any cell, and is probably the species found in the larva state by Baron 

 Osten Sacken in that situation, but not named or described by him, 

 except as being '• reddish." T have also bred a few iiuagos of it from 

 the galls »S'. brassi'coi'h's and *S'. rhoJoidrx, and as I found. May 12th, 

 four of its pupal integuments in a vase containing the small variety of 

 the (lall iS'. batatas — which integuments are readily distinguished from 

 those of C. s. batatas, not only by their much smaller size, but also by 

 the thoracic bristle and antennal horn being only h as long, and immac- 

 ulate instead of black or tipped with black — I must also have bred them 

 from that gall, though the imagos escaped me. As noticed below, the 

 species is double-brooded, the spring brood coming out from last year's 

 galls, and the autumnal brood from the galls of the same season, so as 

 to be in time to oviposit in the same galls for the brood of the follow- 

 ing spring. The two broods were obtained from two distinct lots of 

 galls, each gathered only a few weeks before the insect appeared ; so 

 that it must not be supposed that they bred artificially in confinement. 

 Those bred from the aalls ^S'. brassicoides and S rhndoidrs belonged 

 exclusively to the autumnal brood. Other double-brooded Cecidomi/ia 

 are stated to exist by Osten Sacken {Dipt. N. A. p. 186.) There can 

 be no possible mistake about the identity of the larva, pupa and imago, 

 because on May 3 I bred % 9 imago from cocoons which I had previ- 

 ously extracted from between the scales of the gall ;S'. strobiloides and 

 isolated in a vial, and the other Guest Gall-gnats Obtained from this 

 gall occurred exclusively in the autumn. The very general coexistence 

 of these pupal cocoons with the eggs of an OrchcUmvm (see Proc. Ent. 

 Soc. Phil. III. p. 232) under the scales of the gall *S'. strobiloides^ both 

 of them in very large numbers, was at first very puzzling; and I origi- 

 Qally guessed that the Orthopterous eggs were the pupae of some inqui- 



