Ashy Gray Lady Beetle

Olla v-nigrum has two color variants: gray with black spots or black with red spots. They are usually anywhere between 3.7 to 6.1 mm (0.15 to 0.24 in) in length. Olla v-nigrum is often confused with Chilocorus sp. which usually have more flared elytra and a distinct shape. They do not have white marking on their heads like Olla v-nigrum. Olla v-nigrum spots tend to be triangular and slope away from where the wings meet. Olla v-nigrum lack an infundibulum in female genitalia.

Olla v-nigrum are indigenous to Florida but can be found throughout the continental United States and as far south as Argentina. Olla v-nigrum are found in Hawaii and Guam where they were once introduced due to biological control efforts. Other efforts have led to their introduction in Asia, including establishment in New Caledonia and Reunion Island. Also, the release of Olla v-nigrum has been documented in southeastern France, Israel, and Czechoslovakia, although the status of the beetle in these countries is now unknown due to their population numbers not being documented since their release. Due to competition with the exotic Asian lady beetle (Harmonia axyridis), Olla v-nigrum has become less prominent throughout North America as both beetle species compete for the same broad range of prey, and the Asian lady beetle seems to be less susceptible to parasites. With the Asian lady beetle spreading to South America to countries such as Argentina and Brazil, Olla v-nigrum populations are expected to be negatively impacted. Recent studies have shown that Olla v-nigrum have also begun to appear on the Canary Islands. It was first observed in 2014 on the islands Tenerife and La Palma, followed by Lanzarote and Gran Canaria. Finally, in 2020, Olla v-nigrum was recorded in Madeira.

Olla v-nigrum has an egg stage of about one to two days on average. Compared to other beetles, Olla v-nigrum have a short larval duration of about seven days. The beetle's pupal phase lasts about four to five days. Finally, Olla v-nigrum has an egg-adult phase that lasts around 16 days. Overall, the total cycle period of Olla v-nigrum from larva to adult is about 25 days. From these eggs, more than 80% will usually be viable past the larval stage. Once Olla v-nigrum become adults, they usually show a longevity of around 60 days. The mean interval between generations of these beetles was found to be about 52 days on average. O. v-nigrum larvae possess an elongated body. Their abdomen is segmented. After hatching, this species does not move around much. They remain around the eggs, even consuming infertile eggs.

Olla v-nigrum are known to oftentimes prey on psyllids, a family of insects. Olla v-nigrum populations have been observed to increase in response to increases in numbers of psyllids. Olla v-nigrum usually prey on immature psyllids, such as psyllid larvae. Olla v-nigrum has been observed in nature to specifically prey upon the Asian citrus psyllid (Diaphorina citri) as well as various aphids such as the Schizaphis graminum, Hyadaphis sp., Metopolophium dirhodum, Uroleucon sp., Breviocryne brassicaee L. and Myzus sp. It has been tested whether Olla v-nigrum prey on the Southern green stink bug (Nezara viridula) eggs and nymphs. It has been shown that Olla v-nigrum tend to not prey upon living stink bugs very often. However, they will tend to prey more on dead nymphs of the stink bug. This has been hypothesized to be due to the fact that the Southern green stink bug may have a defensive secretion when it is alive that discourages the beetle from attacking the bug. Even then, only the 4th instars of Olla v-nigrum have been shown to attack the stink bug at a high rate, as the adults tended not to attack the stink bug at all. This species also feeds on eggs and larvae from the Coleoptera and Lepidoptera orders. They even consume aphids from plants. …