|
Pecan Insects
Pecan Weevil (Curculio caryae)Adults are brown to grayish weevils, about 1/2
inch (13 mm) in length. The slender snout is about one-half the length of the body in the male, and slightly longer than the body in the female. Adult feeding prior to shell hardening causes nut drop. Nuts damaged by adult feeding
exhibit a pin-hole sized puncture, frequently surrounded by a dark, moist stain. After pecan shells harden and kernels gel, female weevils oviposit (lay eggs) in the nut kernels. Larvae hatch and feed in the maturing nuts for
several weeks, destroying the kernels. Fully grown brown-headed, creamy white, legless grubs, 1/2 to 3/5 inch (12-19mm) long, emerge from the nuts through a small, circular hole and enter the soil. Adult weevils usually emerge from
the soil between August 1 and September 20.
 |
|
Hickory Shuckworm (Laspeyresia caryana)These are brown-headed,
dirty white caterpillars up to 1/2 inch (13 mm) long that feed inside immature nuts, causing nuts to drop. After shell hardening, larvae feed inside green shucks, preventing proper kernel development and causing shucks
to adhere to shells. |
|
|
|
|
Black Pecan Aphid (Melanocallis caryaefoliae)Black pecan aphids are tiny,
about 1/20 inch (1.2 mm), dark-green to black-green to black. They feed on both upper and lower surface of leaflets, causing bright yellow rectangular areas which later die and turn brown. Premature leaflet drop and
complete defoliation can result. |
|
|
|
|
Yellow Pecan Aphids:
Black-Margined Aphid (Monellia caryella)
Yellow Hickory Aphid (Monelliopsis nigropunctata)These are tiny, about 1/20 inch (1.5 mm), soft-bodied, greenish-yellow. They feed primarily on under surface of leaflets. A black sooty mold may
grow on the sugary honeydew secreted by the aphids. Heavy honeydew and sooty mold on the surface of leaflets may interfere with photosynthesis. |
|
|
|
|
|
|
|
|
|
Pecan Leaf Scorch Mite (Eotetranychus hicoriae)The mites are very tiny, about
1/125 inch (.2 mm) long, pale green, 8-legged pests. They feed primarily along the midribs and veins on the underside of leaflets, causing dark brown blotches which later appear as scorched, dead areas. Infestations normally begin
on the lower branches and spread upward. Heavily damaged leaflets turn entirely brown and drop, often resulting in premature tree defoliation. Other mite species occurring occasionally may cause leaflet edges to thicken and curl;
produce small brown to black irregular spots alongside veins; or cause graying along mid-ribs on the upper surface of leaflets. |
|
|
|
|
Stink Bugs and other True Bugs:
Southern Green Stinkbug (Nezara viridula)
Leptoglossus spp., Euchistus spp. and othersThese are green to brown, broadly to narrowly shield-shaped, true bugs 1/2 to 1 1/2 inches (13-38 mm) long. Front half of wings leathery; back half membranous.
Scutellum, or triangle between the base of the wings, is less than 1/2 length of wings. Piercing-sucking mouthparts arise on the front of the head. Adult feeding on immature nuts causes nut interiors to darken (black pit) and
subsequent nut drop. Feeding occurring after pecan shells harden causes brown to black, pithy spots on the kernels (kernel spot), reducing nut quality. |
|
|
|
Pecan Nut Casebearer (Acrobasis nuxvorella)Pecan nut casebearers are green
caterpillars up to 1/2 inch (13 mm) long and feed in developing nuts in May and June. Infested nuts are usually held together at their base by silken webbing containing conspicuous, dark, grass eliminated by the larvae.
One larvae can destroy all the nuts in a cluster. Second generation larvae also attack the nuts but damage is usually less severe. Later generations feed on foliage or in green shucks, causing little
damage. |
|
|
|
|
|
|
|
|
Pecan Phylloxera (Phylloxera devastatrix)
Pecan Leaf Phylloxera (P. notabilis)These are very tiny, 1/50 inch (.5 mm) long, yellow-green, aphid-like insects contained in galls or
abnormal swellings of leaves, leafstalks or stems. Stem infesting forms frequently cause weakened shoots which finally die. Leaf infesting forms are not normally a serious pest of mature trees but may contribute to
premature defoliation of individual trees when infestations are heavy. |
|
|
|
|
Pecan Leaf Casebearer (Acrobasis juglandis)With shiny brown heads, these
brown-green caterpillars are about I / 12 inch (2 mm) long and feed on unfolding buds and young foliage in spring. Older larvae, up to 5/8 inch (15mm) long, may be contained in a small, gray case which they construct
about themselves while feeding. Heavy spring infestations can keep trees partially defoliated for several weeks. Later generations feed on the undersides of leaflets and cause little damage. |
|
|
|
|
Pecan Spittlebug (Clastoptera achatina)
Alder Spittlebug (C. obtusa)
Groups of nymphs are about 1/12 inch (2mm) long, covered by masses of white, frothy, spittle-like material, feed and suck juices from leaf stems and nut stalks. They are commonly found in the spring and again in
mid-summer. Heavy infestations may damage the terminal shoots, reducing the nut crop. |
|
|
|
|
|
Taken from Insect and Disease Indentification Guide for IPM in the Southeast, The University of Georgia, Cooperative Extension Service Bulletin 849,
September 1981 |
|
|
