THE AJ^IEEICAN ENTOMOLOGIST. 



105 



Galls made by Gall-giiats (CWidomyia). 



Thk Fi\k-( <jxk AVili.ow-gali, 

 {Strohiloides, Osteii Sackcu), 

 Fig-. 8l'.— This p;all grows, often 

 in the most iirol'use abmulance, 

 on the ti|) ol' the twig' of the 

 llcart-Ieaved Willow {Sallxcov- 

 data), siiig'le Ixishes sometimes 

 bearing- over a iiundred galls, 

 but never more than one gall be- 

 ing found upon one twig. The 

 gall-gnat that produces it (Fig. 

 83) appears in April or early in 

 Coiur-Gi.r'ouewh.ic. Mav, and tlic gall commences its 

 rowth shortlv afterwards, and is full sized by 



[t'.g 



the middle of Ju- 

 ly. When young 

 and immature it 

 is spherical and 

 enveloped in a 

 dense mass of 

 foliage, which 

 g-radually falls 

 off towards the 

 autumn, and by 

 November the 

 twig on which 

 it grows, if small, is already killed for an inch 

 or two downwards. At this date the lai-va may 

 be found embedded in the very heart of the gall, 

 and enclosed in a delicate membranous cocoon, 

 somewhat of the texture of gold-beaters' skin, 

 and thrice as long- as the larva itself. In this 

 cocoon it reposes without eating anything until 

 (he following spring, when it cliauges into the 

 pupa, and shortly afterwards bursts the pup.i- 

 shell and escapes in the perfect or winged state. 

 The gall itself is manifestly noiliing lint a de- 

 formed and enlarged bud ; for leaf after leaf may 

 be peeled away from it any time in the winter, 

 as you would strip the leaves from a cabbage 

 one after the other, until finally the larva that is 

 quietly reposing in the very heart of the bud 

 becomes exposed to view. It is remarkable 

 that, although the leaves of the Heart-leaved 

 Willow are always sharply toothed on their 

 edges, those of the gall that grf)ws upon it are 

 never toothed at all. 



There is a species of green Catydid iidiabiting 

 Willows, which is peculiarly addicted to depos- 

 iting its elongate cylindrical eggs, for safe keep- 

 ing through the winter, under the scales of this 

 gall, as many as seventy-one of its eggs having 

 been counted in a single gall. In the spring 

 these eggs hatch out, and the young larviB leave 

 the dry galls, and disperse themselves in various 

 directions for the purpose of obtaining green 



food. There is also a very minute Guest Gall- 

 gnat {Cecidomyia albovi(tata,'\\a\%\\), scarcely 

 one-third as large as the species (Fig. 83) that 

 makes the gall, but otherwise very nuich of thi; 

 same appearance, which deposits its eggs in the 

 same situation. The larvie, however, that hatch 

 out from these eggs, instead of leaving the gall, 

 as do those of the Catydid just now referred to, 

 remain in it till they have reached maturity', de- 

 riving their entire subsistence from the sap that 

 they manage to extract from its leaves, in two 

 galls, each containing of course but a single gall- 

 making larva, we have counted as many as 

 forty-one of these guest laiwa? full fed and ma- 

 ture ; and what is singular, numerous as the 

 guests often are, they never seem to interfere in 

 any degree with the health and prosperity of 

 their host, by cutting off his due supply of sap or 

 otherwise interfering with his domestic arrange- 

 ments. AVith sudi exuberant profusion has 

 Xature provided for the multiplication of life 

 and happiness, and so carefully has she man- 

 aged that, whether in the animal or in the vege- 

 table kingdom, nothing shall go to waste, nothing 

 be lost, nothing be created in vain! 



TiiK Cabuagk-simjout Wii-Low-gali. (^Salich 

 brassicoides, "Walsh). Fig. 84. I'nlike the pre- 

 ceding, this gall is social in its location, as many 

 as a dozen of them some- 

 times growing from a 

 single twig, like the 

 sprout ^• on ;i cabbage- 

 stalk. It diti'ers from 

 that species also in not 

 being contined to the ex- 

 treme tip of a twig, but 

 more usually taking its 

 origin from the side of a 

 twig or sma'l branch. 

 Furthermore, it is always 

 found exclusively npou 

 the Long-leaved Willow 

 (Snlix lont/ifolia), and 

 we have several times 

 noticed bushes of this and 

 of the Ileart-leaved Wil- 

 r„ioi— Giwn iq^^- ji,j,( jy iniiabited by 



tlie Pine-cone Gall, promiscuously intermingled 

 and eacli bearing its peculiar gall alone, and 

 never that which is appropriate to its neighbor. 

 Kundamentally, the structure of the Cabbage- 

 sprout (iall is the same as that of thelMne-cone 

 Gall, but, as will be seen at once from the figure, 

 it difters from that species in the leaves being 

 more open and less deformed from their normal 

 shiipe, and also in their retaining their natural 

 green color instead of being covered with glau- 



