braconid wasps

Macrocentrus is a large genus of small braconid wasps. They occur worldwide but are most common in Europe and North America. There are at least 180 described species worldwide, and it is believed that there are hundreds more undescribed species. Forty-six species occur in North America north of Mexico, and at least 14 species occur in Minnesota.

Most larger Macrocentrus species are solitary, while most smaller species are gregarious.

Macrocentrus are predatory wasps. The larvae are internal parasites of moth caterpillars, beetle grubs, and sawfly larvae, that can be found in stems, under bark, in flower heads, or in rolled or spun leaves. In sone species, the females use their long ovipositor to insert an egg directly into the body of the host. In others, they lay an egg on the host, and when the egg hatches, the larva bores into the body of the host. The larva eventually kills the host.

Some species are used as biological control agents to manage agricultural pests of corn, cotton, and soybean crops. One species, Macrocentrus cingulum, was introduced into North America in an attempt to control the European corn borer.

Macrocentrus are slender-bodied and usually about 4 mm in length. Their color ranges from black to brick red.

The head is usually dark brown to black. The back of the head (occiput) is not margined. The antennae are often longer the than body. They have 16 or more segments, a long scape at the base, a short pedicel, and a whip-like section (flagellum) with 14 or more segments (flagellomeres). The first flagellomere is much longer than the scape.

The first segment of the abdomen is constricted into a narrow petiole connecting the front part (mesosoma) and rear part (metasoma) of the body. The petiole is slightly concave below. The depression at the base of the petiole (laterope) is large and deep.

The metasoma is elongated. On females, the egg-laying structure (ovipositor) protruding from the rear is always as long or longer than the metasoma.

The legs are long and slender. The second and smallest segment (trochanter) of each leg has peg-like teeth on the outer side at the tip. On the hind leg, the fourth segment (tibia) has an inner spur that is 0.3 to 0.5 times the length of the first segment (basitarsus) of the last part (tarsus) of that leg.

Sources

24, 27, 29, 30, 82, 83.

This genus has no common name. The common name of the family Braconidae is braconid wasps, and it is used here for convenience.

Location: Albany, NY