THE AMERICAN ENTOMOLOGIST. 



105 



growth slioitl> iiftcrwiird 



Galls maile by fiall-snats (Crridomyia). 



TllK I'lXK-COMO AVii.i.ow-<;.\Li, 

 {Sfroliiloides, Ostun Sacken), 

 Fig'. 82.— Tliis gall grows, often 

 in the most profuse abundance, 

 on the tip of the twig of the 

 Ileuit-leaveil AVillow (Salix ror- 

 (lata). single bushes sometimes 

 bearing over a hundred galls, 

 but never more than one gall be- 

 ing found upon one twig. The 

 gall-gnat that produces it (Fig. 

 So) appears in April or early in 

 Max, and the gall commences its 

 1 is full sized by 

 the middle of Ju- 

 ly. AVhen young 

 and immature it 

 is spherical and 

 enveloped in a 

 dense ma.ss of 

 foliage, which 

 gradually falls 

 off towards the 

 autumn, and by 

 November the 

 ( oini — i!:.i. kisii twig on which 



it grows, il >.mall, is already killed for an inch 

 or two downwards. At this date the larva 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 tlu-ice as long as the larva itself. In tliis 

 cocoon it reposes without eating anything until 

 the following spring, when it changes into the 

 pupa, and shortly afterwards bursts the pupa- 

 shell and escapes in the perfect or winged state. 

 The gall itself is manifestly nothing but a de- 

 formed and enlarged bud : tor 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 arc always sharply toothed on their 

 edges, those of the gall tluit grows upon it are 

 never toothed at all. 



Thei-e is a species of green C'atydid inliabiting 

 "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 larvie leave 

 the dry galls, and disperse themselves in various 

 directions for the purpose of obtaining gi-een 



food. There is also a very minute Guest (iall- 

 gnat {Cecidonu/ia alborittata,y\'a\sh), scarcely 

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

 makes the gall, but otherwise very much of the 

 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, lu two 

 galls, each containing of course but a single gall- 

 making larva, we have counted as many as 

 forty-one of these guest larvic full fed and ma- 

 ture; and what is singular, numerous as the 

 guests often are, they never sccni to interfere in 

 any degree with the health and prosperity of 

 their host, by cutting oft' his due supply of sap or. 

 otherwise interfering with his domestic arrange- 

 ments. With such exuberant profusion has 

 Nature 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 

 1)0 lost, nothing be created in vain I 



The C.\BBAtiE-.si>uouT Wii.i.ow-GAi.i, {HuUvix 

 hnissicoides, Walsh). Fig.. 84. Unlike 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 

 spi'onts on ;i cabbage- 

 stalk. It differs from 

 that species also in not 

 being coiitiiied 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 

 bund exclusively upon 

 Long-leaved Willow 

 {Sfili'x kinijifdlla). and 

 wc have several times 

 noticed bushes of this and 

 of the Heart-leaved AVil- 

 ( „i,,i_(iivi)i j^j^^y (.[jjij jg inhabited by 



the Pine-cone (iall, promiscuously intermingled 

 and each bearing its peculiar gall alone, and 

 never that which is appropriate to its neighbor. 

 Fundamentally, the structure of the Cabbage- 

 sprout (rail is the same as that of the Pine-cone 

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

 it ditters from that species in the leaves being 

 more open and less deformed from their normal 

 shape, and also in their retaining their natural 

 green color instead of being covered with glau- 



