102 



THE PRACTICAL ENTOMOLOGIST. 



There is no instance on record where, having esta- 

 blished itself in any settlement, it afterwards leaves 

 that settlement and passes on elsewhere or disap- 

 pears. Colonies are from time to time pushed for- 

 ward in all directions, especially towards the unoc- 

 cupied region that lies to the eastward. But the 

 old original homestead is never deserted. Farmers 

 and others will govern themselves accordingly. On 

 the whole, I am satisfied that in a region of coun- 

 try which has been already fully occupied and pos- 

 sessed by this little pest, it will not pay to attempt 

 to grow potatoes in towns and thickly settled sec- 

 tions, where one is surrounded by neighbors who 

 plant potatoes, and think it too small business to 

 make war upon such an insignificant creature as a 

 Bug. In that case, no matter how much pains the 

 farmer may take to clear his own vines, fresh armies 

 will be perpetually invading him from the fields of 

 his less diligent neighbors, and finally he nill have 

 to give up in despair, and own himself beaten. 

 The best chance is where a farm is located several 

 miles from any potato-growing neighbor. In such 

 a situation 5Ir. Brown, of Woodbury Co., Iowa, 

 states that he raised a moderate crop in 1866, in 

 spite of the Bug. " As soon as the first rows 

 could be seen," he say.s, "the bugs were found on 

 nearly every plant. A day's work at this time, 

 before eggs are laid, i.s equal to weeks of work 

 later. [Yes, for these are the ones that have passed 

 the winter underu;round, and start the first brood. 

 B. D. w.] These earliest bugs were picked 

 closely, but for the first week they increased. After 

 this eggs were found, but the bugs decreased in 

 number, with each picking. A small black-winged 

 yellow bug appeared soon after eggs were found, 

 and fed upon them, rendering valuable assistance. 

 [Probably some species of Ladybird. B. d. w.] 

 The good bug was kindly treated. There were 

 scarcely any potato-bugs seen after the 1st of July, 

 but all that were seen were destroyed." (^Ibid, 

 March 9, 1867 j. 



The Law lays it down as a general rule, that a 

 man must so use his own property as not to damage 

 his neighbor. But the Law does not always pr:ic- 

 tice what it preaches. If it did, it would prohibit 

 every man from keeping cattle which are notori- 

 ously breachy. If it did, it would inflict capital 

 punishment upon all the sheep-killing dogs in the 

 country. If it did, it would make it a penal of- 

 fense to allow a single Canada thistle to run to 

 seed. If it did, it would not permit a slovenly 

 orchardist to grow, every year, millions of the moth 

 which produces the " Caterpillar'' of the Apple- 

 tree, so as to stock the whole country with hun- 

 dreds of millions of " (!aterpillars" next season. 

 If it did, it would compel every fruit-grower to 

 gather up and destroy all his wormy fruit, so that 

 his neighbors might not be plagued next year with 

 the Curculios which he has raised. If it did, it 

 would prohibit every man from growing potatoes 

 in the infested district, unless he destroyed all the 

 Potato-bugs that he raised, so that they should not 

 trouble his neighbor. But we must console our- 

 selves with the reflection that this is a free country, 



and that every free-born American citizen claiii; i 

 the privilege of making himself a public nuisanci', 

 as often as he chooses, and to as great an extent as 

 he chooses. b. i>. w. 



answUks to cokeespondents. 



M. W. Philips, Mississippi. — The little thorn-like, coni- 

 cal, green "galls," about i inch long, growing in bunches 

 of three or four from the under side of the leaf of the 

 "Texas Mustang" Grape-vine, are made by some unde- 

 scribed species (if Gall-gnat (Cc6'/rfo»«yia). I formerly re- 

 ceived very similar ones from Mr. Foster, of Pennsylva- 

 nia, which grew on the Isabella grape-vine, a cultivated 

 variety of the noi-thern Fox grape. (See Practical Ento- 

 mologist, Vol. I, p. 101.) Whether the two are identical, 

 I should not like to decide positively, but I incline to 

 think that they are not. The general rule — to which, 

 however there are numerous exceptions — is that each spe- 

 cies of gall is confined to a distinct sjiecies of plant; and 

 even when the .-^ame gall occurs on distinct species of 

 plants, those species invariably belong to the same bota- 

 nical genus. There are whole hosts of these "galls," as 

 naturalists call them, or unnatural growthsof every concei- 

 vable shape, size and color, nihde by insects belonging to 

 many different Orders. The great bulk of those found in 

 the United States are at present undescribed and unknown 

 to science. Baron Osten Sacken enumerates no less than 

 58 species made by different species of Gall-Hy {Cynijis) 

 on different species of Oak, and I am myself iicciuaiuled 

 with many others which are undescribed. The well 

 known "Oak-apples," which grow exclusively on the 

 Black Oak, are a familiar example of a "gall ;" and there 

 is another very distinct kind of "Oak-apple" growing OD 

 the Red Oak, which differs in containing no sjiongy sub- 

 stance inside it, the central cell, in which the larva of the 

 Gall-fly lives, being only connected with the skin of the 

 Oak-apple by regularly radiating lilaments, instead of the 

 interval between the two being filled up with dense 

 brown sponge. Both the above galls are made by a Gall- 

 fly (O/nips, Order Ilymenoptera.) Other galls on other 

 genera of plants are made by Sawflies (JenMrrf/o family 

 in the same Order). Others by Plant-lice (Aphin family. 

 Order Heteroptera). Others by small moths (Order Le- 

 pidoptera). Others by diHercut groups of two-winged flies 

 (Order Diptera),and especially by the Gall-gnats (Cccido- 

 mt/ia). all of which are slender, long-legged insects, hav- 

 ing much the appearance of a common Musketo, except 

 that they lack his long blood-thirsty beak. In every ease 

 the larva or larvai'of the parent fly lives inside the gall, 

 deriving nourishment from the unnatural growth which 

 is technically termed a "gall." In the case of the Plant- 

 lice, the mother insect lives and jiropagates inside the 

 gall, bringing forth alive therein a numerous progeny of 

 young plant-lice. One gall of this kind, shajied some- 

 what like a cock's comb, is very abundant on the upper 

 surface of the leaves of a species of Elm, and many other 

 kinds may be found on Poplars and Hickories. In most 

 other cases the Jlother-fly simply deposits an egg or eggs, 

 along with a drop of poison, in the infested part of the 

 plant, and then goes off and dies. In due time tlie egg 

 hutches out into a larva, and the larva subsequently 

 changes into a fly — destined to run through the same cy- 

 cle of changes as the Mother-fly from which it took its 

 origin. Thus year after year the breed is propagated. 

 Taught by a mysterious instinct, every kind of gall-pro- 

 ducing insect knows the particular kind of plant in which 

 alone its future larvpe can subsist, and selects that kind 

 with as unerring certainty as the best Botanist in the 

 whole world could do. 



Besides the Grape-vine gall which you send, and the 

 similar ones received from Mr. Foster, I ani acquainted 

 with a very much larger one which is undescribed, and 

 Osten Sacken has described two other kinds, all of the 

 above being made by Gall-gnats. You may ask how I 

 know that your galls'are made by Gall-gnats, seeing that 

 I cannot have had time as yet to breed the fly from them. 

 The answer is, that there is a peculiar "breast-bone," as 

 it is called, found in the larv:c of all known (iall-^nats 

 (Cearfomj/ia family), .and never in any other kind ot lar- 

 va. Consequently, I had but to open one, of your gall.-;., 



