'? -J : )<- U.S. DEPARTMENT pF AGRICULTURE, BUREAU OF HJT0M0L9GY CIRCULAR Ko. 148. L O. I l< >W AKI >. I ntomoWM «ikI ( h.rf ol Burcu. TWO DESTRUCTIVE TEXAS ANTS. \V. I). HUNTER, //i Charge of Southern Field Crop J . OFFKE : 1*12 BUREAU OF C\ TO UOLOGY. L. O. Howard, Entomologist and <'hi. Hopkins, in charge of forest insert investigations. VV. I>. Hunter, in charge of southern field crop insect investigations. F. M. Websti b, /'// charge of cereal and forage insect investigations. A. I,. Qttaintance, tn charge of deciduous fruit insect investigations. E. F. Phillips, in charge of bee culture. D. M. Kot.i ss, in charge <>f previ nting spread of moths, field worfo, Rolla P. Cubbie, in charge of (tlitoriu! work. Mabel Colcobd, in charge of library. Southern Field Crop [nsect Investigations. W. I >. Hunter, in charge. V. V. Bishopp, A. II. Jennings, II. 1'. Wood, \V. V. King, engaged in tick life- h istory in vest i<) Hi mi it In (Itiinjt nf Southern Field-Crop Insiii Investigation*. THE CUTTING OR PARASOL ANT. i l tin texana Buckley. » The so-called cutting or parasol ant (Atta fa xana Buckle} | is well known to residents i>t" the region in which it occurs. The colonies are located in sandy soil, generally in the timber, and consist of kyvi mounds of considerable extent covered with numerous craters about 1^ Inches in diameter. The ants have the habit <>f cutting the leaves from a great variety of plant > and of carrying them to their nests. In many case- the attack i- concentrated on one tree, which may be entirely defoliated in a single night. The species is of a reddish- brown color. The colonies contain individuals showing great dif- ferences in size. as will be explained later. DISTRIBUTION. The range of this species is rather restricted. It is known only from a limited area in south-central Texas, This area extends from the Brazos River as far north as Waco to the Gulf, westward as Ear as San Antonio, and southward to the vicinity of Alice. The ant is most common in the valley- of the Colorado. Guadalupe, Comal, and San Antonio Rivers. In these situations it i- evidently increasing in numbers from year to year. In many cases the nests occupy the land practically continuously for many mile- up and down the valley-. II \1MT-. The nests consist of underground chambers with several openings or craters. The surplus openings seem to he provided for the pur- pose <»f ventilating the underground passages. The nest- are located 28482*— Cir. US- 12 Z TWO DESTRUCTIVE ANTS. generally in sandy soil. The more compact soils seem to be un- favorable for their construction. A very common location for a colony is a sandy promontory, well lighted by the sun, in the bend of a river. The large irregular mounds arc due to the leveling by the wind and rains of the circular ridges of sand, brought from beneath the surface, which surround the openings. Consequently, each of the mounds is an indication of the activity of the ants for many years. Beneath these mounds are numerous chambers connected by narrow passages, and there may he direct connection by these channels over an area of several hundred square feet. The habits of this insect have attracted great attention from scien- tists and others. The ants cut the leaves from trees and carry them to the nests. Each leaf is finely divided and made into small pellets. In this work the mandibles and legs of the ants are utilized. The small masses are placed upon the so-called fungus garden, where they furnish a growing medium for the growth of a fungus which furnishes the colony with food. As the supply of fungus is con- sumed the ants add to the old mass, so that eventually the nests are found to contain large spongy formations on the outer portion of which the slender threads of the fungus are growing. Evidently the ants exercise great care in preventing the contamination of the fungus garden by any but the sole species of fungus that is utilized. The ant is active throughout the greater part of the year. In fact, it becomes quiet for only a very short time when the winter cold is most severe. It is disinclined to work during very hot weather. During the cooler months its activity extends through- out the day, but during the summer it is confined to the night. The distance over which foraging expeditions take place may be 200 yards or even more. Practically all species of plants seem to be suitable for food, although it is noticeable that only one species is attacked at a time. Dr. W. M. "Wheeler, who has made very careful studies of these ants, has noted that the same colony may feed upon a wide variety of plants at different times, but he never observed the individuals of a colony collecting different varieties at the same time. 1 Among cultivated crops, cotton, corn, fruit trees, sorghum, and many others are attacked. Among wild plants, forest trees are favored, and frequently the Spanish moss is used. The various species of oaks seem to be more or less immune, either on account of the texture of the leaves or the tannic acid they contain. This immunity is by no means absolute, however, as Dr. Wheeler and Mr. J. D. Mitchell have observed the ant- making use of such rough leaves as those of the live oak. i Wheeler, W. M. The Fungus-Growing Ants of North America. Bui. Amer. Mua, Nat. Hist., vol. 23, Article XXXI. pp. 7J!l-742. PWO DESTRUCTIVE AHTB. 8 The colonies of this ant are formed bj the ili^lit of the females to some point imi far distant from the nest. The queen alights, digs beneath the surface, deposits a small quantity of the fungus from the original nest, and on it deposits a number of egg i ORMS. This ;mt occurs in five forms, namely, soldiers, large workers (media), small workers (minima), males, and females. The soldiers are from 1" (<> 12 mm. in length, with enormously developed heads. The large workers, or media, resemble the soldiers, although 1 1 • » - head is somewhat smaller, and the length of the body is between ■\ ;iii(l 9 nun. The small worker forms, called minima, are from t.5 to 2.5 nun. in length. The head is >till -mailer than in the media. Each of these three forms has a special function in the nest. The soldiers are concerned primarily with the protection of the nest. They do not sting, l>nt bite with their mandibles, which arc strong enough to draw blood. The large worker- and small workers are busied principally with the gathering of lease- for the fungus garden ami the preparation of the material on which the fungus grows. The remaining form- are the male- and female-. These are much larger than the other form-. The female is about I s nun. in length. The color i- dark brown, although the legs are somewhat reddish. The body i- covered with dense tawny hair. The wings, which are shed soon after the flight of the queen, are reddish In-own. especially along the anterior borders. The male- are from 13 to 1 I nun. long with a head of -mall -i/e which contrasts greatlj with that of the worker form-. The body is densely covered with long yellowish hair-, a- i- the case with the female-. l:l PR] S8ION. The fact that tlii- ant doe- not continue to attack one specie- of plant continuously, but changes from one to another at frequent interval-, causes it to he of less importance in the destruction of vegetation than it would he otherwise. Nevertheless, the damage to growing crop- i- frequently heavy, ami complaint- have become more numerous in recent year- on account of the greater abundance of the ant.-. In many place- considerable area- of land are not planted to crop- on account of the danger of attack. In all such situations it i- necessary to resort to repressive mean-. The best method of control i- undoubtedly by mean- of potassium eyanid.' Mr. .1. 1). Mitchell ha- conducted the experiments upon 'Tin' nae of potassium cyan Id In water notation against n i-r followed by Messrs. i; S Woglum and Win Wood (See Journal of Economic (Entomology, v. a. 1, ■ i'"'- \i,- ii i) Marsh b d It. (Se< Bui 04 Pi i v i s Depl Agr . Boj Knt . pp. Tt 78, L910 I 4 TWO DESTRUCTIVE ANTS. which this conclusion is based. He used 98 per' cent potassium cyanid at the rate of 1 ounce to 1 quart of water. After careful mixing this liquid was poured into each of the openings in several nests, a quart to each opening. In every case it was found that the destruction of the colony followed after one or two applications. The cost of this method is small, but of course will assume consider- able proportions in areas where the ants are very numerous. Even under such conditions it will undoubtedly well pay for the expense and is advised above all methods that can be followed. The use of carbon bisulphid is not practical on account of the very extensive excavations the ants make in the sand. Some may be killed, but effective work can not be done unless the insecticide is forced into the earth by pressure, and this requires special apparatus. Moreover, the expense would be much greater than in the case of the cyanid method just described. Some years ago certain persons in southern Texas followed the destruction of this ant as a regular business. They used sulphur and a special apparatus for forcing the fumes into the nests. The ma- chine consisted of an oven in which the sulphur was burned. The fumes were passed through a pipe by forced draft, and the end of this pipe was inserted into the ground in the middle of the colony. Before the oven was started all of the openings of the nest were care- fully closed. It is said that remarkable success accompanied this method. It may be found to be advisable to use this method for large areas of the infested lands or where several planters can cooperate. Mr. C. L. Marlatt has described a method of destruction of ants which is in use in Cuba : It consists in digging a hole C, feet deep by 3 or 4 feet wide in the midst of the colony. This hole is filled with dry brush and a roaring fire started. Into this is then poured a bucketful of powdered sulphur. The opening is closed with a large iron plate. Through a hole in the center of this plate air is forced down into the burning mass with a large bellows. 1 THE AGRICULTURAL OR HILLOCK ANT. (Pogonomyrmex barbatus molefaciens Buckley.) The nests of the agricultural or hillock ant (Po77. 1010. PWO DESTRUCTIVE ANTS. D in- 1 kii'.i noN. The agricultural anl occurs from the Brazos River westward. West of San Antonio it is replaced l>\ closely allied forms. Farther north, in Kansas and Nebraska, a distinct species i/'. occidentalis Cress.) occurs. The agricultural an( is conspicuously a residenl of open places and does not occur in wooded localil it \r.i i-. This iint -warm- early in the season, generally after a rain. At such times tin" males and females come out of the ne-t in great num- bers, covering the ground for many feet Mating takes place at tlii- time, after which the females fly away. When they alight their wings are cast and they begin to dig a cell for ;i new colony. The males after mating arc driven away by the worker- or killed if they persist in returning to the nest. At the time of this swarming multi- tudes of the ants arc destroyed by birds and horned Lizards Many year- ago it was announced that the agricultural anl actu- ally plants certain grasses in order to obtain quantities <>t' Beed to use in provisioning the nests. In fact, it was on this supposition thai one of the common names which have come into use was given it. Upon careful investigation, however, it was found thai the ant does not plant seed intentionally, although it undoubtedly doe- so acci- dentally. The fact- were broughl out by Prof. \V. M. Wheeler. The seeds of several species of <_rra-s and common weed- are taken into the nest-. When the moisture is too great in the nest -on f these -ted- sproul and thu- hecoiue unsuitable for fond. Under such cir- cumstances the ant- carry out the sprouted seeds and deposit them in the immediate vicinity of the ne-t where many take root and grow. Of course, this can not be considered intentional planting of the seed-, because the ants deal with the sprouted grain exactly as they would with any substance that was unsuitable in their ne-t-: that is, they .-imply carry it out and throw it away. n \m \cr. The economic importance of the agricultural ant i- due t<> the fad that it will not allow vegetation to grow in the immediate vicinity of its nest and to it- powerful sting which it uses on the slightest provocation. If the colonic- happen to be in field- such a- alfalfa, corn, or cotton, the area of loss may amount to considerable, and the same i- true to a certain degree of pasture and range land-. More over, in fields which are mowed the mound- interfere with the work- iiiiT of the machine, and the anl- are likely to attack the horses. There i- some degree of compensation for the loss of the land cleared by the ants. It will be noted that in a circle ju-l outside of the area 6 TWO DESTRUCTIVE ANTS. that is cleared the plants grow with great luxuriance. Frequently these plants become quite conspicuous in the field. This redoubled growth is due apparently to the fact that the underground tunnels of the ants loosen up the soil and have somewhat the effect of deep plow- ing. It is not likely that the increased growth under these condi- tions offsets entirely the loss in the area where no plants are allowed to grow, but it is sufficient to reduce the importance of the insect to sonic extent. Mi - . J. I). Mitchell, who has made many careful obser- vations on this species, believes that the actual damage inflicted is generally overestimated. The sting of the agricultural ant is at least as severe as that of a bumblebee. It is speedily inflicted on any animal that approaches the nest. Consequently, colonies located in the vicinity of houses or on roads or paths frequently become decided nuisances. The best local applications for stings are aqua ammonia or bicarbonate of soda (baking soda). When fainting or dizziness occurs, as i- fre- quently the case, a few drops of ammonia taken internally will lie helpful. NATURAL ENEMIES. Natural enemies exert some repressive influence upon agricultural ants. The most important enemy among the birds is the great - tailed grackle ( Megaquiscalus major ?narrourus), commonly known as the jackdaw. The following additional Texas birds are known to prey upon species of Pogonomyrmex. according to records in the Biological Survey: Upland plover (Bartramia Ivngicauda) , burrow- ing owl {Speotyto cunieularia hypogcea), Texas night hawk (Clior- deiles acutipennu texensis), scissor-tailed flycatcher (Museivora for- ficata), kingbird (Tyrarmus tyrannus), redbird (Cardinalis eardi- nalis), and mockingbird {Mim/us polyglottos) . The horned lizard (Phrynosoma comutum) includes agricultural ants as a pari of it- regular diet. REPRESS K IX. As in the case of the cutting ant. the destruction of this species can best be brought about by the use of the solution of potassium cyanid in water. Mr. J. D. Mitchell conducted experiments at Vic- toria. Tex., which showed that this was a perfectly satisfactory method. It is much cheaper and easier of application than in the case of the cutting ant on account of the fact that the underground portion of the nest is much less extensive. A pint of liquid is suf- ficient for even a large colony, though sometime- a second applica- tion may be necessary. Carbon bisulphid is also a good remedy and can be applied in a very simple maimer. All that i^ necessary is to pour about 2 PWO DESTRUCTIVE ANTS, 7 ounces into the opening of the nest. The opening need nol !><• i l A> tlif gas is much heavier than air, it sinks into the innermost i'-. ami kill- all of the ants in the colony. Setting fire to the liquid is of ii" benefit. In Fact, it i- likely to lessen its efficiency. The poison nia\ lie applied at any linn- of the day, rcgardlef of the number of the ant- that an tside tin' nest. The destruction of tin- colony depends upon tin' killing of tin' queen, and -In- remains in tin- not at all times, except when the swarming flight i- under way, tor a very short time in the spring. Sometimes Paris green or other arsenicals are used in the attempt to control this species. They air generally applied bj -imply pour- ing a handful into thr openings. Many of the am- an' killed, l>nt a large pari <>t' the brood is not affected, ami the colony -"on becomes a- numerous ;i- ever. In some cases where tlii- method has been followed persistently tin' ants have moved their nest a few fret away ami have become reestablished perfectly in a Bhort time For these reasons the use of arsenicals can not be considered satisfactory. Another method sometimes followed, which is of little practical use, i- trapping the ants in bottles, [fa large bottle is buried in the ground in the vicinity of tin' nest with the neck tln-h with the sur- face the ants soon begin an exploration ami fall inside. The noise they make in tin- bottle attracts many others, in tlii- way in the vicinity of ;i populous colony a large bottle may be filled in a short time. The objection to this procedure is that ii only reduces the strength <>t' the colony. The immature stages ami the queen are not affected, and the colony booh regains it- former numbers. Approved : d \mi> W'n SON, § n tary of Agrit idture. Washington, D. C, January 18, 1912. ADDITION \ I. COP! ii in. iv I"' | nx-'ir- • 1 from the Sitkkin ■HI ■ >»■' DOCDM ' Oilier, Washington, D I - <-opy UNIVERSITY OF FLORIDA lllllllllillll 3 1262 09216 5678