46 



THE AMEEICAN ENTOMOLOGIST. 



of this particular Family of Insects — were pro- 

 nounced by him to belong to two distinct spe- 

 cies*. Yet they were all bred from the same 

 lot of galls, gathered off the same gronp of wil- 

 low bushes, and preserved in the same breed- 

 ing-vase. Hence we may see how impossible 

 it sometimes is to distinguish species, from the 

 mere comparison of dried cabinet specimens by 

 the closet-entomologist. 



The perfect Fly makes its appearance about 

 the middle or latter end of April, when the sexes 

 couple as usual, and the female shortly after- 

 ward deposits a single egg in the leaf of the 

 Heart-leaved AVillow, or occasionally in that of 

 the Glaucous Willow (S. discolor). For cut- 

 ting the tiny slit, which is to receive the egg, 

 into the substance of the leaf, she employs the 

 small pair of saws which are found at the tail 

 of all female Sawflies, and which we figured 

 from a microscopic inspection of those of this 

 particular species on page 19 (Fig. 10, a). 

 Along with the egg she deposits a minute drop 

 of a peculiar poison, through the action of which 

 upon the vegetable tissues of the plant, com- 

 bined after the lapse of a few days with the 

 huugry guawings of the young larva that hatches 

 out from the egg, the apple-like gall is called 

 gradually into existence. By the end of July 

 the larva is full-grown, and is then about one- 

 fifth of an inch long, the body of a pale green- 

 ish white color and the head pale brown, with 

 the usual lateral eye-spots blackish. Besides 

 the six true or jointed legs in front, it has seven 

 pairs of .sham legs (pro-legs) behind, as usual 

 in larvas belonging to this genus. It generallj' 

 passes into the pupa state inside the gall, and in 

 the April of the succeeding year the pupa-shell 

 bursts open and the winged fly appears, to re- 

 iterate the same old cycle of oijerations year 

 after year. 



If we cut into a great number of these Wil- 

 low-apple galls early in July, we shall often 

 find a good many of them to contain, not 

 the 20-legged larva of the Sawfly that makes 

 the gall, but a small whitish legless grub very 

 similar to the grub of the common Curculio, 

 but of a much smaller size. In August there 

 is produced from this grub a small Snout-beetle, 

 which we may call the Sycophant Curculio 

 (Anthonomus sycoplianta, Walsh), about half 

 the size of the common Curculio, and nearly ot 

 the same general shape, but of a uniform brown- 

 black color, except that the wing-cases are 

 almost entirely blood-red. This Snout-beetle, 

 is what we have denominated a "Guest-beetle," 



*See the Paper on Willow Galls by the Senior Editor in 

 Proc. Ent. Soc. Phil. VI. p. 25i. 



that is, it does not make a gall for its own future 

 progeny like the Willow-apple Sawfly, but it 

 lays its egg in the immature gall of that unfor- 

 tunate insect, thus sponging upon the labors of 

 its more industrious compeer for food and lodg- 

 ing for its own ofispring. The intrusive egg 

 then hatches out into a minute larva, which has 

 the wonderful instinct to destroy the rightful 

 tenant of the gall, either in the egg or in the 

 early larva state ; thereby monopolizing for its 

 lazy self the delicious gall, wliich the provident 

 Mother Sawfly had intended for her own ofi'- 

 spring. The larva of the Sycophant Curculio, 

 when fully fed, changes into the pui^a state in- 

 side the gall, and in August, as already stated, 

 the winged beetle emerges, destined to pass the 

 winter in the ijerfect state, and in the ensuing 

 spring to rob another brood of the poor ill-used 

 Willow-apple Sawflies of their own rightful 

 tenements. 



" But," it will be asked, "how do you know 

 ftU this? How do you know that it is not the 

 Sycophant Curculio that is the veritable archi- 

 tect of this gall, and that the Willow-apple 

 Sawfly does not in reality sxJonge upon the 

 Snout-beetle for food and lodgings, instead of 

 the Snout-beetle, as you assert, sponging upon 

 the Sawfly?" We answer that we have reared 

 numbers of this same Sycophant Curculio. not 

 only from the Willow-apple gall, but fi-om two 

 perfectly distinct galls {S.desmodioideSyWsAsh, 

 and S. nodus, AValsh), one of which is peculiar 

 to the Humble Willow {S. humilis) and the 

 other to the Long-leaved Willow {S. longifolia). 

 Both these two galls produce Sawflies, one of 

 which belongs to the same genus (Nematus') as 

 the Willow-apple Sawfly but to a distinct spe- 

 cies, while the other one is not only specifically 

 distinct but belongs to a distinct genus (Uuura) . 

 Now, if it is the Snout-beetle, and not the Saw- 

 fly, that makes the Willow-apple gall, it must 

 be this same identical Snout-beetle that makes 

 these other two galls on two other species of 

 Willow. But, upon that supposition, we 

 should have the same insect generating three 

 entirely distinct galls, which is physically as 

 impossible as for the same cow to produce in- 

 differently either a calf, a lamb or a pig. There- 

 fore it necessarily follows that our Snoiit-beetle 

 cannot be a gall-maker, and as we find numbers 

 of them in all their stages in three perfectly dis- 

 tinct Willow-galls, it must be a Guest in each 

 of them. For, as it feeds upon the substance of 

 the gall, and not except incidentally upon the 

 larva that in reality generates the gall, it cannot 

 be a mere Parasite. 



Besides the 20-legged larva of the Gall-making 



