added an equal amount of dehydrated lime. The applications are preferably made early in the morning when the foliage is damp and the dust readily adheres to it; however in large groves it is often impossible to delay for such favorable conditions. In cold weather the dry sprays do little or no good, due to the slow liberation of the fumes. During the past few years liquid sprays of the commercial limesulphur have met with great favor and promise to completely do away with the dust sprays. The commercial product is reduced to from 2 to 23 per cent and applied as a fine mist under a pressure of from 150 to 200 pounds. Care must be taken not to use the spray stronger than is absolutely necessary, for in some cases severe burnings occur to young lemons. Applications of both the dry and liquid sprays should be made as soon as the spiders appear in any considerable number. Natural Enemies.-Natural enemies play an important part in the control of the citrus red spider and are often responsible for keeping its numbers so small as to do little damage. Conventzia hageni Banks, the green lacewing (Chrysopa californica Coq.) and the brown lacewings (Sympherobius angustus Bks. and Hemerobius pacificus Bks.) are important enemies belonging to the order Neuroptera. The minute black ladybird beetles (Stethorus vagans and S. picipes), a staphylinid beetle (Oligota oviformis Casey), the thrips (Scolothrips sexmaculatus Perg.), the larvae of a fly (Arthroconodar occidentalis Felt) and the carnivorous bug (Thriphleps insidiosus Say) prey upon the red spiders. INSECTA OR HEXAPODA (Class). INSECTS. *ORDERS. The following study is based upon the order as a unit of classification. This is done to avoid confusion and to aid in the more systematic study of these important animals. The following is a list of orders and suborders, beginning with the lowest: 1. Thysanura.-Silver-fish or silver moth, spring tails, bristle tails. Collembola.-Achorutes, Sminthurus. 2. 3. Orthoptera.-Earwigs, cockroaches, praying mantids, walking sticks, grasshoppers, katydids, crickets. 4. Platyptera.— 5. 1. Suborder Corrodentia-White ants or termites, psocids or bark lice and embiids. 2. Suborder Mallophaga-Biting bird lice. Plecoptera.-Stone flies. 6. Ephemerida.-May flies. 7. Odonata.-Dragon flies. 8. Thysanoptera.-Thrips. 1. Suborder Homoptera-Cicadas, plant lice, scale insects, white flies. Suborder Heteroptera-True bugs. 3. Suborder Parasita-Head and body lice. 10. Neuroptera.-Lacewings, including brown and green lacewings so well known as beneficial insects. 11. Mecoptera.-Scorpion flies (Bittacus sp.). 12. Trichoptera.-Caddis flies. 13. Lepidoptera.-Moths and butterflies. 14. Coleoptera.-Beetles and weevils. 15. Diptera.-Two-winged flies. 16. Siphonaptera. Fleas. 17. Hymenoptera.-Horntails, sawflies, wasps, bees, and many small and large parasites. *This classification is based upon that of Dr. J. W. Folsom. Because of their non-usefulness in such a work as this, the following orders will not be considered: EARWIGS, COCKROACHES, PRAYING MANTIDS, WALKING STICKS, GRASSHOPPERS, KATYDIDS AND CRICKETS. All of the members of this order, with the exception of the praying mantids (Mantida) and certain exceptions among the earwigs (Forficulida), are destructive to vegetation and most of them are serious pests to cultivated crops. Though most of them possess four wings, a few genera and species have none at all. The fore wings are called tegmina and differ from those of most insects in that they are leathery being a means of protection for the delicate thin hind wings which are used for flying. All the members have strong and well developed mouthparts for biting and chewing. The metamorphosis or change from the young to the adult is gradual and scarcely noticeable. The first born. always resemble the adult, with the exception that they have no wings and undeveloped sexual organs. To follow out the systematic arrangement of this order, the families are usually arranged as follows: 1. Forficulida; 2. Blattida; 3. Mantida; 4. Phasmida; 7. Gryllida. While practically all of these are of great interest and often of economic value, only the last three are deemed of sufficient importance to be included in a work of this character. These will be considered in the order as given above. The Forficulida are placed in a separate order Euplexoptera by many entomologists. ACRIDIIDE (Family). SHORT-HORNED GRASSHOPPERS OR TRUE LOCUSTS. The insects of this family include the most destructive members of the entire order and are common practically everywhere. They are separated from the other families by their short antennæ, which are never as long as the body; by the three-jointed tarsi; and by the short plated ovipositor. The hind legs are large and long to enable them to travel rapidly by jumping. With the exception of a few species all have well-developed wings and are able to make long and continuous migratory flights. FIG. 12. The Rocky Mountain Locust (Melanoplus spre- The members of this family are very prolific and increase in such numbers as to cause great ruin to vegetation. Many species migrate long distances, leaving a trail of devastation in their wake. The eggs are usually laid at the bottom of a hole drilled into the soil by the abdomen of the female (Fig. 12). As the winter is passed in this stage, the eggs are thoroughly protected from cold and moisture by a fluid. cement secreted by the female for this purpose. In the spring the young hoppers emerge from the holes and begin to feed upon the first green vegetation and develop very rapidly. In the early fall they begin to mate, the females depositing their eggs before winter. Control. The control of grasshoppers is often a perplexing problem, due to their great numbers and migratory habits. Their appearance is often so sudden as to take the farmer wholly unawares and the damage done before he can defend his crops. Extensive experiments on control work have been conducted by trained men all over the world, the results of which have made the hopper invasions less dreaded. The reclamation of arid lands and the extension of agriculture to the foothills and deserts have eliminated many of the old and favorite breeding places, and greatly reduced the size and numbers of migrations. In this State the most destructive species are controlled as follows: Poisoned Bran.-In California the poisoned bran bait has proven exceedingly effective. This is recommended by J. S. Hunter (Bull. 170 Cal. Agrel. Exp. Sta.), as follows: Bran Molasses (cheapest) 40 pounds. 2 gallons. 5 pounds. The bran should be wet so that water can be just squeezed out of a lump held in the hand. After this, stir in the molasses and then the arsenic. Let stand over night and stir well before placing in the field, so as to allow the poison to penetrate every particle. The poison should be scattered in small piles, about the size of an egg, in front of the path of the hoppers throughout the infested area. In orchards bait should be placed at the trunk of each tree. This bait should be either occasionally moistened or renewed. Criddle Mixture. This is one of the poisons used in the East and Middle West with such effectiveness and is prepared as follows: Paris green Common salt Fresh horse dung... 1 pound. 2 pounds. 60 pounds. The paris green is first mixed with water to form a paste and then thoroughly stirred into the horse dung with the salt. The mixture is then scattered in some such manner as is the poisoned bran. Protecting Orchard Trees.-The general practice has long been to whitewash the trunks of trees to prevent the grasshoppers from crawling up into the trees. If occasionally renewed this wash does great good in this way and is worthy of recommendation. A broad tanglefoot band near the base of the trunks will catch many of the hoppers but if not applied very thickly the larger and stronger ones will pull out. Poison baits placed at the bases of the trees will keep most of the hoppers from attempting to ascend to the foliage. Cultivation. As previously stated the grasshoppers lay their eggs in the fall in small holes in the soil an inch or two deep. The eggs hatch in the spring and the young easily escape. Late fall or winter plowing from four to six inches deep will so cover the egg sacs as to make the escape of the newly hatched hoppers impossible. The greatest menaces are the places held by speculators, who are indifferent to the ravages of these pests. Such localities afford excellent breeding places and in every community where the hoppers are bad, steps should be taken to see that such places are plowed at least during the winter months. A thorough harrowing or disking after a rain serves to fill up the burrows and to crush many of the egg masses. |