1882. J 



THE LANCASTER FARMER. 



131 



possessed so much vitality uiuler such di'.- 

 plcting circumstances. The worm was brought 

 to us, witli a part of the tomato i)lant on 

 wliicli it was found, on the 9th of August, 

 and on the morning of the 12th most of the 

 cocoons were deftly cut off at the upper ends 

 and fully three hundred small four-winged 

 (lies had issued forlli, and were vainly trying 

 to make their escape from the glass jar in 

 which we had conlined the worm. Tlic worm 

 still continued to crawl over the plant but 

 was evidently much weakened. It seem(;d 

 also to be annoyed by the pressure of the Hies, 

 and feobly struck about witli both ends, as 

 though it desired to get rid of something very 

 disagreeable. 



The worm belongs to the crepuscularian 

 Lepidoptcra (Twilight-flying moths) and the 

 little four-winged flies belong to their para- 

 sitic Hyriunoptera, of which there is a very 

 large family [U-lmcionoiidin') — the Mknnjaster 

 congrcgatn, or a specific closely allied. Suj)- 

 posing the worm to be about dying we at- 

 tached it to a cork and suspended it in a small 

 jar of alcohol ; and, although it suffered us to 

 run a needle and thread through its head, and 

 by a similar process attach a small leaden 

 weight to its tail, with almost entire impunity, 

 yet, when we suspended it in the alcohol, it 

 writhed vigorously for live minutes, and de- 

 tached about twenty-five of the follicles from 

 the thoracic segments. The worm and all the 

 flies are carefully jirescrved in alcohol. There 

 cannot be much less than three hundred and 

 fifty of them, but we shall base our estimates 

 on the round number of three hundred in our 

 remarks. This phenomenon surely furnishes 

 food for practical reflection in its connection 

 with insect economy. Suppose this worm to 

 have been a female, which, had she developed 

 the moth, would have been able to have de- 

 posited at least three hundred eggs (on one 

 occasion we counted more than that number) 

 the possibilities, therefore, existed to have re- 

 produced three hundred horn-worms at least. 

 Now, we will suppose that one-half of that 

 number would have been females endowed 

 with the same reproductive powers, and the 

 result would have possibly been an increase 

 of forty-five thousand horn-worms for next 

 season, aud all the legacy of a single worm. 

 Perhaps out of these forty-five thousand not 

 five thousand would have fallen victims to the 

 most efficient remedies, nor yet that number 

 have reached maturity. What then would 

 have become of the other thirty thousand. 

 Let us see. It would be going too far beyond 

 the pale of probability to suppose that only 

 one-half of the parasites would have been 

 females, for the females among these insects 

 always greatly exceed the males in number — 

 a hundred, a thousand, and often ten thous- 

 and to one. This has especially been the case 

 among the gregarious gall-insects which are 

 parasitic on plants. Out of these three hun- 

 dred little microyasters we must, therefore, 

 claim two hundred aud seventy females at 

 least, capable of reproducing eiglity-one thous- 

 and parasitic enemies to the three hundred 

 horn-worms, or over seven millions against 

 the forty-fly e thousand horn- worms, perhaps 

 not as probabilities, but as ultimate possibili- 

 ties, all other things being equal. 



Now, we advise tobacco-growers, gardeners, 

 fruit-growers and agriculturists in general, 



that, whenever they discover a horn-worm, or 

 any other kind of worm, infested with these 

 or similar parasites, tliey "severely let it 

 alone," and allow nature to take its course. 

 There is no danger of such worms ever doing 

 any further damage, and by crushing them or 

 tramping them under foot, they may be only 

 destroying a multitude of little insect friends. 

 During the past foi'ty years we have liad at 

 least one hundred worms of different kinds 

 infested by parasites brought under our-ol> 

 servation, and we never knew a single in- 

 stance in which any of them survived. All 

 eventually perished. Therefore, the wisest 

 economy is not to distur1)them, but to permit 

 the parasites to develop, and when developed 

 they will find another or scores of other 

 worms that will serve as niduses for future 

 generations. They will find those, perhaps, 

 that eluded the utmost vigilance of the to- 

 bacco cultivators, who generally relax their 

 watchfulness as soon as the crop is harvested, 

 after which hundreds of worms, left in the 

 field, are permitted to mature and go into 

 winter pupation in the ground. Should any 

 of these late worms go into the ground, car- 

 rying in their bodies the eggs or immature 

 larva; of the parasites, althoush they might 

 be able to eftect their pupal transformations, 

 yet the moths will never be evolved. 



Perhaps tlie naked caterpiliars (those quite 

 or nearly destitute of hair) are more liable to 

 these parasitic infestations than iliose that 

 are protected by long stiff hairs, but even 

 some of these will develop a fevi'. We have 

 found on opening the tough follicle of the 

 " sack worm " [Thyridopicryxephemariformis) 

 on several occasions, that the inner cavity 

 was packed nearly full of the small cocoons 

 of a hymenopterous parasite. Now, no bird 

 can dislodge the larva; of this insect from its 

 strong cocoon, which it always carries with it 

 wherever it goes. We have seen both chickens 

 and birds attempt it, but they always have 

 abandoned it without accomplishing their 

 object. But it seems these parasites can cir- 

 cumvent those almost otherwise unapproach- 

 able worms, which affords an ample illustra- 

 tion of the superiority of parasitic infestation 

 over all other known remedies, either natural 

 or artificial. Of course, there are different 

 genera and different species even among those 

 that affect worms in a similar manner. Those 

 before us now constructed white cotton-like 

 cocoons, but there are others more silky. 

 They are, however, not all white ; some are 

 difl'erent shades of yellow, some drab-colored, 

 and some brownish. 



Of course, in one sense, parasitic infesta- 

 tions may be classed among natural remedies, 

 but in this paper wc wish them imdenstood as 

 entirely distinct. Natural remedies may 

 therefore be interpreted to mean those ani- 

 mals that naturally or incidentally feed on in- 

 sects themselves or provide them for their 

 young — such, for instance, as birds, poultry, 

 skunks, moles, swine, etc., and may also in- 

 clude such predaceous insects as capture or 

 feed upon other insects for their own suste 

 nance, such, for instance, as dragon-flies, 

 tiger-beetles, ant-lions, wheel-bugs, camel- 

 crickets and many others. But all these are 

 either spasmodic or indiscriminate, or both, 

 in their antagonism to the insect world. They 

 destroy friendly and innoxious insects, as well 



as those that are noxiou.s, and some of them 

 only devour insects when they can obtain 

 nothing better ; others survive only for a 

 brief season, and others again desist when 

 they are surfeited, so that they are inconstant 

 in their antagonism with insects. 



Nothing could be more spasmodic than the 

 application of artificial remedies for the de- 

 struction of our insect pests, for tliese are 

 mainly governed by the caprice of man. They 

 seldom if ever anticipate the eflluxor influxof 

 noxious insects, and are generally only ap- 

 plied when the enemies of vegetation have 

 been augmented and have become destructive. 

 The remedy is then liable to be applied at the 

 wrong time and place, or the quality of the 

 material used may be inferior, or the quantity 

 may be excessive or insufficient, or it may 

 not come in contact with the subjects int- 

 tended to be destroyed. Many people use a 

 remedy as a patient takes a pill— shuts his 

 eyes, swallows it at random, and then lets it 

 work its way through the stomach and bowels 

 as best it may. We by no means intend to 

 disparage either natural or artificial remedies, 

 for often contingencies arise when it is abso- 

 lutely necessary to do sometliing, and that 

 pronijitly, too, in order to rescue a crop from 

 destruction; but when the evil is overwhelm- 

 ingly present, it is very seldom that artflcial 

 remedies ever amount to anything. The 

 Chinch Bug, the Rocky Mountain Grass- 

 hopper and the Colorado Potato Beetle have 

 not been exterminated beyond a perad venture, 

 and may become abundant whenever meteo- 

 rological aud other combmations are favor- 

 able. 



Parasitic infestation, however, occupies a 

 very different ground in its relations to the 

 noxious tribes; it is not merely spasmodic in 

 its operations, lint on the contrary, it is con- 

 stant aud continuous, and in obedience to an 

 unalterable dictate of nature. We might 

 almost as reasonably expect a fish to cast its 

 spawn in a hay-mow, or a robin to build its 

 nest on the bottom of a mill dam, as for a 

 parasitic insect to find any other nidm for its 

 eggs than the body of a living caterpiller, 

 grub or worm; and there is sufficient analogi- 

 cal evidence to lead to the conclusion that 

 there is not an insect species on earth that has 

 not one or more parasitic enemies. In the 

 general equipoise of nature's economy the 

 bane and antidote go hand in hand, but 

 through human intervention this equilibrium 

 is disturbed or entirely destroyed. This is 

 especially the case where the noxious insests 

 of one realm have, through commercial inter- 

 course, been introduced into another of a 

 similar climate. The bane may be introduced 

 and not the antidote, and hence an insect 

 that was not specially destructive in its native 

 country may become an unmitigated scourge 

 in a foreign one. The "white cabbage *but- 

 terfly," when first introduced into the United 

 States, increased more rapidly, and conse- 

 quently was more destructive than it is now. 

 This was supposed to be owing to the fact 

 that its parasite (Pleromahis pupantni) had 

 not yet been introduced. But that parasite 

 is in the country now, and through its inter- 

 vention the butterfly has, in some localities, 

 become almost exterminated. 



Three years ago we received from Franklin 



*Pieria rapu;. 



