Bulletin STATE OF ILLINOIS DEPARTMENT OF REGISTRATION AND EDUCATION DIVISION OF THE NATURAL HISTORY SURVEY STEPHEN A. FORBES, Chief Vol. XVII. BULLETIN Article VI. Some Causes of Cat-facing in Peaches BY B. A. PORTER, U. S. Bureau of Entomology, Vincennes, Indiana S. C. CHANDLER. Illinois Natural History Survey. Corbondale. Illinois R. F, SAZAMA, U. S. Bureau of EntomoloBy. Vincennes, Indiana PRINTED BY AUTHORITY OF THE STATE OF ILLINOIS URBANA, ILLINOIS March, 1928 STATE OF ILLINOIS DEPARTMENT OP REGISTRATION AND EDUCATION A. M. Shelton, Director BOARD OF NATURAL RESOURCES AND CONSERVATION A. M. Shelton, Chairman William Teelease, Biology Henry C. Cowles, Forestry Edson S. Bastin, Geology William A. Noyes, Chemistry John W. Alvord, Engineering Chaeles M. Thompson, Representing the President of the University of Illinois THE NATURAL HISTORY SURVEY DIVISION Stephen A. Forbes, Chief SCHNEPP & Barnes, Printers Springfield, III. 192S S2971—3M i Volume XVII. Artkle VI. SOME CAUSES OF CAT-FACING IN PEACHES* B. A. Porter, S. C. Chandler, and R. F. Sazama Introduction For a number of year.s the peach growers of .southern IlHnois and southern Indiana, as well as those of some other sections of the Middle West, have been suffering losses from a peculiar deformation of the ])eaches that generally has been supposed to be caused by the feeding of thrips. The injury has been named "cat-facing" by growers in several localities, and this term is now in common use in the Aliddle West. Simi- lar injuries occur in peach orchards in the Northwest, in Georgia and the Carolinas, and probably in other localities, but the present paper reports investigations restricted to southern Illinois, southern Indiana, and west- ern Kentucky. Nature of the Injury The injury known as cat-facing usually consists of scarred sunken areas around which the tissues are more or less distorted, but it sometimes takes the form of closed lesions, which vary from slight dimples or de- pressions to extensive puckered areas. No pubescence develops on an in- jured area, and in most cases the area is brown, corky, and harder than the normal flesh of the fruit. Such injury is obviously the result of the feeding of insects when the peaches are small. The more open scars sug- gest surface feeding by some kind of chewing insect, but the other scars look more like the work of sucking insects. On a given tree, the injury sometimes tends to be localized ; while some ])arts may be free of injury, almost all of the peaches on other parts may be disfigured. Apparently, the insects causing the injury often move from peach to peach, injuring almost every one they encounter. Different varieties of peaches appear to be injured in varying degrees. The J. H. Hale often shows more cat-facing than the Elberta grown nearby. One instance has been observed in which at least 2T per cent of * The inve.stigatioiis on which this paper is based were conducted simul- t.ineously at two place.s—at the entomological field laboratory maintained by the Illinois State Natural History Survey at Carbondale, Illinois, under the direction of Mr. W. P. Flint, and at the field laboratory maintained at Vincennes. Indiana, by the U. S. Bureau of Entomology, under the general supervision of Dr. A. L. Quaintance, and in cooperation with the Purdue University -Agricultural Experi- ment Station. Acknowledgment is made to Mr. W. L. McAtee, of the Bureau of Biological Survey, for the determination of the species of Lygus and Euschistus referred to in this paper. (261) 262 Illinois Natiral History Sikvey Billktix the peaches on Redbird trees were injured, while only 1 1 Jjer cent of those on the J. H. Hale nearby were injured, and only 5 per cent of those on the Elberta next to them. Losses The commercial losses resulting- from cat-facing are hard to estimate. The percentage of peaches damaged is very variable. Although in indi- vidual orchards the injury has run as high as 50 per cent or even 66 per cent, the general average in this region is less than 15 per cent. Table I CorxTS OF Cat-Faced Peaches ix Represextative Orchards IX JACKSOX, JoHxsox, Uxiox Axn Pulaski Cocxties, Ozark Peach Sixtiox of Southerx Illixois j Per cent of peaches cat-faced Year Orchards examined Maximum Minimum Average 1925 Some Caisks of Cat-facing in Pkaciies 263 at one end with a cloth sleeve. (See Figure 1.) Such cages may be made readily to enclose a twig bearing tw-o to four small peaches. In most cases the cages were put into place immediately following petal fall. W'herever it was necessary to cage larger peaches, they were carefully examined, and all those showing any sign of injury were removed. In no case did injury appear in check cages. Several seasons of experience were recjuired to enable the writers to manipulate the cages so as to produce the maxinumi number of typical in- juries. Comjjiete proof of the "guilt" of insects suspected as agents is not obtained as easily as may be supposed. The mere fact that an in- sect injures a peach when caged with it and deprived of other food, is not in itself complete proof that the insect is causing cat-facing in the orchard. Fig. 1. Tree showing cages used in determining wliat insects cause cat- facing in peaches. Carbondale, Illinois. 1926. Field obser\ations are necessary in order to determine v>hether or not it normally feeds on peaches in the open. On newly formed peaches it is difficult to adjust the period of insect feeding so that the injury will not be overdone and cause the peaches to drop. When the peaches are fur- ther developed before being injured, they are less likely to drop; but the normal feeding period of certain of the insects, at least, is then nearly over, and the resulting lesions are not so closely similar to typical cat- facing. All of the insects that we consider resjxMisible for cat-facing have been observed repeatedly in the orchard in the act of feeding on peaches, with their mouth parts actually inserted into the peach tissue. This is the tinal step in determining the causal agents. 264 Illinois Natukal Hi.story Suuvky Billetix SOME INSECTS THAT CAUSE CAT-FACING The Takxished Plant Bug The Tarnished Plant Bug {Lygus pratcusis L. ) has been recorded a number of times as feeding on peaches, particularly by Lowe' and Taylor.- This small, inconspicuous bug (see Figure 2) came under suspicion sev- eral years. ago as a possible cause of cat-facing, and the type of injury done by it was described in a previous paper by Porter.'* The fresh injuries consist of rather extensive irregular areas of broken-down tissue. In some cases the skin is left intact except for a central puncture, but in Fig. 2. Tarnished Plant Bug, Lygus prateiisis L. (Insert is approx- imately natural size.) Fig. 3. Stink bug, Eiischisttts ser- viis (Say). (Insert is approx- imately natural size.) others the skin as well as the underlying tissue is broken down. The fuzz over the lesion is usually undisturbed, although the point where the beak of the bug was inserted may be marked at first by a yellowish or brown- ish stain, which later turns black. If the skin has not already broken down, it dries and sloughs off, and the inner surface of the cavity becomes corky and rough as it heals over. The surrounding tissues usually grow more rapidly than the injured spot, producing more or less distortion. The bugs in feeding apparently inject some poisonous material that causes 'Lowe, V. H., 1900. Miscellaneous Notes on Injurious Insects. New York Agr. Exp. Sta. (Geneva) Bull. 180. p. 135. = Taylor, E. P., 1908. Dimiiles in Apples from Oviposition of Lygus pratensis L. J. EC. Ent. 1, p. 370. = Porter, B. A., 1926. The Tarnished Plant Bug as a Peach Fruit Pest. J. Ec. Ent. 19, pp. 43-48. Some Causes of Cat-facixo ix Peaches 265 the tissues to disintegrate. Hypodermic injections of the juices of crushed bodies of the bugs produced lesions somewhat similar to cat- facing, but injections of distilled water, as well as injuries produced by probing with a sterile needle, failed to result in such lesions. Peaches injured in cages by the Tarnished Plant Bug were carried through to the mature cat-face stage in i;c2G and 19-37. thus completing the proof that this insect plays a part in the production of cat-facing. Two of these peaches are shown in Figure 4. The bugs that feed on peaches in s])ring are those that have become full-grown in the previous autumn and have passed the winter in the adult stage in or near the orcharu. The Tarnished Plant Bug normally passes its life on \arious weeds and other succulent ]ilants. It seems to be especially fond of the plants in the daisy family, such as wild asters and Fig. 4. Peaches injured in cages by Tarnished Plant Bug. Illinois. 1926. Carbondale. fleabancs. as well as the leguminous plants, such as red clover, alfalfa, and sweet clover. These last two also provide the bugs with very acceptable hibernating quarters, since, in addition to winter protection, they furnish satisfactory food verj- late in fall and very early in spring. Many of the hibernating bugs are attracted to the ])each blossoms, and for a period of two or three weeks thev do the feeding that results in the injuries just described. The appro.ximate period during which the bugs are present on the trees, as indicated by the number of bugs caught on the sheets when jarring for curculio, is shown in Figure 5. Very few eggs are laid on the peach trees, and after a short time most of the bugs desert the trees and return to various weeds or cultivated crops to lay their eggs. The Tarnished Plant Bug is said to pass through several gen- erations during a season, and to hibernate almost entirely in the adult stage. 266 Illinois Natural Histohy Sirvky Billktin Plum Curculio Tarnished Plant Bug Pig. 5. Graphs showing numbers of Tarnished Plant Bug and Plum Curculio caught on sheets by early-morning jarring of 10 unsprayed peach trees, Carbondale, Illinois. The jarring was done between 6:00 and 7:00 a.m. The insects were turned loose after counting, in order to keep conditions as near natural as possible. So.MK Causes of Cat-facing in Pkaciiks 267 Fig. 6. Peaches injured in cages by three kinds of stink bugs: top row. Euschistus viiridUiriuf,- : middle row. £.'. tristirimus : bottom row. E. sei'vus. Vinceunes, Indiana. 1927. Photon bij R. L. Coffin, of Jap- anese Beetle Laboratory. 268 Ili.i.nois Natural Histohy Sihvf.v Bvli.etin Stink Bugs Four species of stink bugs* produce cat-facing. ( See Figures 3 and (i. ) These large, angular bugs, gray to brown in color, are often verj' abundant in peach orchards in spring, and we have observed them re- peatedly in the act of feeding on small peaches. When the peaches are very small, most of the injured ones shrivel and drop, but when the peaches are larger, most of those that have been fed upon remain on the tree and become distorted or cat- faced. The stink bugs continue to pro- duce cat-facing for five or six weeks after petal fall, or until the peaches become an inch or more in diameter. Feeding continues after this stage of development, in diminishing amounts, and the lesions produced later are less extensive. Two of the species involved, E. variolarhis and E. fristigmus, were very abundant during 1927 in southern Indiana, and the Fig. 7. Colony of small stink bugs, clustered on leaf near egg mass from which they hatched. Vincennes, Indiana. 1927. (About six times natural size.) other two species mentioned were probably responsible for very little of the cat-facing there in that season. A few of the stink bugs lay eggs in small groups on the leaves of the peach trees. The egg masses observed have usually been in multiples of seven, fourteen being the most common number. On hatching, the young bugs remain clustered around the egg mass for a few days until they un- dergo the first molt ( see Figure T ) ; they then disperse and feed for a short time on the leaves and on the young peaches, if they find any nearby. * Eu^chistus variolarhis (Palisot de BeauvoLs) ; E. euschistoides (VoUenhoven) : E. servus (Say); and E. IrisHgmus (Say). Tliese are tlie more common membei-s of this genus in southern Ulinois and southern Indiana. Some Causes of Cat-facing in Peaches 269 Their feeding may cause slight dimples on the fruit, out of which ooze small quantities of gum ; this kind of injury, however, is not very common, since the small bugs disappear from the peach trees soon after the first molt. They are found in abundance on weeds in the orchard in early sum- mer, particularly on the young plants of one of the fleabanes. Erigcron canadensis L. Later on, bugs of all ages may be found in large numbers in fields of soy beans and cow peas. In 1!)2T, one of the stink bugs {E. variolarius) was found in large numbers in red clover fields. They may be found, however, to a greater or lesser extent on almost any grow- ing plant. Stink bugs are said to pass usually through two generations during a season, and they hibernate in the adult stage. CURCULIO The Plum Curculio, Conotrachclus nenuphar Herbst. so well known to all peach growers, produced cat- facing on peaches in our cages. The Fig. 8. Peach injured in cage by curculio. Carbondale, Illinois. 1926. Fig. 9. Curculio ovipositing on a peach. (About four times nat- ural size.) work of this insect is best known to the growers by the dropping of peaches early in the season and the occurrence of wormy fruit at harvest. When the injured fruit remains on the tree, it is more or less distorted. (See Figures 8 and 9.) Other Possible Causes While we are confident that the list of insects already named includes the important causes of cat-facing in southern Illinois and southern In- diana, it is probable that further in\-estigations will show that other in- sects are also capable of producing cat-facing. 270 Illinois Natithal HisTdiiy Si'UVEY Bii.i.ktix The Green Soldier Bug, Acrostcnium hilarc (Say), one of the largest of the stink bugs, is occasionally seen in peach orchards, and its young stages sometimes cause considerable injury to the fruit* in the form of numerous small dimples (see Figure 10). None of the mature bugs have been available for caging tests in spring. A few peaches may be cat- faced by this species, but it is so scarce in the peach orchards of this section that it cannot be an important factor. A species of thrips, FranklinicUa tritici (Fitch), which is often jjres- ent in large numbers in the peach blossoms and around the small fruit, was at first suspected as the cause of cat-facing, but we have been unable to connect this insect with the trouble. In one season in particular (1925) thrips were very abundant in our cages (they are so very small that they can pass through the ordinary screen cage), but no sign of injury ap- peared until other insects were introduced. Even when the normal popu- lation was augmented by the addition of fifteen to twenty thrips to each Fig. 10. Peaches injured by young of Green Soldier Bug, Acrosternum hilare (Say). Vincennes, Indiana, 1927. Photo hy R. L. C'offln, of Japanese Beetle Laboratory. peach, no injury appeared. Field observations and counts have failed to show any relation between thrips abundance and amount of cat-facing. The fruit in some orchards in which thrips have been almost entirely ab- sent has suiTered severe cat-facing. As a result of these studies, we believe that the work of thrips is a negligible factor. Relative Importance of the Different Insects We can make no definite statement at present that will hold true for every year, or in every peach section, or even in all parts of the same section, as to the relative importance of the different species implicated in 'Whitmarsh, R. D., 1917. The Green Soldier Bug. Ohio Agr. Exp. Sta. Bull. 310. Some Causes of Cat-facixg ix Peaches 271 producing cat- facing. The curculio is probably of less importance in this respect than the sucking bugs—a belief which is supported by the fact that serious cat-facing injury occurs in some peach orchards in the Pacific Northwest where the curculio does not occur. If it were possible to distinguish the injury caused by each of the dif- ferent insects, it could be determined which insect is of the greatest im- portance in individual orchards. Although the different injuries when fresh may be identified with some degree of certainty, they cannot be dis- tinguished one from another after they have healed over. Host Pl.axt Rel.^tioiXS \\'ith the excei)ti(_)n of the I'lum Curculio. which is probably a lesser factor, the insects involved in this problem do not breed to any extent on peach. They are very genera! feeders, and may be found on any one of a long list of food plants. The Tarnished Plant Bug seems to favor plants in the family Compositae. especially the daisies, the fleabanes, and the wild asters. It also breeds freely on the legumes, but may be found on almost any other plant. ^ The stink bugs are, likewise, very general feeders and may be found on a great many different kinds of plants. Among their preferred host plants may be mentioned red clover, cow peas, and soy beans. The pres- ence of these bugs on jieach fruit in the spring is merely incidental and in no way essential to their life cycle. The plant relationships of the Plum Curculio are not as extensive as those of the other insects involved. Of the cultivated plants aside from peach, the curculio feeds regularly on apple, plum, cherry and other fruits, vvhich are often planted close to peach orchards. Of the wild host plants, wild haw and wild plum are ])robably the most important. HiBERN.MION OF THE T.M